industrial design

A Short Course in Industrial Design

Eskild Tjalve Senior Lecturer, Department of Engineering Design, The Technical University of Denmark

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First published in Denmark in 1976 as 'Systematisk udformning af industriprodukter'

First published in English 1979

© E. Tjalve, 1979

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B r i t i s h L i b r a r y C a t a l o g u i n g in P u b l i c a t i o n D a t a

Tjalve, Eskild A short course in industrial design. 1. Engineering design I. Title

620'.0042 TA174 78-41280

ISBN 0-408-00388-X

Typeset by Butterworths Litho Preparation Department

Printed in Scotland by Thomson Litho Ltd . , East Kilbride

Preface

The c rea t ion o f a new p r o d u c t takes in m a n y levels o f a c t i v i t y and m a n y ski l ls , o f w h i c h t he f i r s t and f o r e m o s t are those o f design engineers and indus t r ia l designers. I t is easy t o recognise the ex t remes w h e n c o m p a r i n g the responsib i l i t ies o f the design engineer and t he indus t r ia l designer, b u t n o t so easy t o say where the respons ib i l i t y o f one ends and the o t h e r begins.

T h e design engineer is invo lved in design w h i c h is o f t e n k n o w n by o t h e r names, e.g. ske tch ing , deta i l design, d i m e n s i o n i n g , etc . A cons iderab le par t o f the w o r k o f design engineers and indus t r ia l designers consists o f t he same act iv i t ies , i.e. f o r m u l a t i o n o f suggestions o f shape, ' m o d e l l i n g ' o f these (ske tch ing , d r a w i n g or hardware m o d e l l i n g ) , invest igat ing and appra is ing the var ious poss ib i l i t ies . These act iv i t ies invo lve the creat ive m i n d at m a n y levels and are the sub ject o f th is b o o k , w h i c h n o t o n l y i n t roduces the s tuden t t o the pr inc ip les o f evo lv ing a des ign, b u t surveys the c r i te r ia by w h i c h these are assessed. T h r o u g h o u t th is b o o k the w o r d 'designer ' has been used as a b lanke t t e r m f o r people w o r k i n g w i t h design ( i .e. engineers, designers and others) o f p roduc ts .

The con ten ts o f th is b o o k shou ld be seen as par t o f t he design t echn ique . In the overal l p lan f o r p ro jec t eva lua t ion and design o n l y the me thods connec ted w i t h the f ina l phases o f design p ro jec t have been descr ibed.

The danger o f f o r m u l a t i n g sys temat ic m e t h o d s in c o n n e c t i o n w i t h c o n s t r u c t i o n w o r k , is t h a t o thers are led i n t o t h i n k i n g t h a t a sys temat ic approach necessari ly gives the r igh t answer. Th is is just n o t so. T h e mos t e f fec t ive so lu t i on is achieved by the r igh t balance o f systemat ics and i n t u i t i o n . T h e sys temat ic approach shou ld t he re fo re be seen as the f o u n d a t i o n f o r t he app rop r i a te a t t i t u d e t o i n n o v a t i o n , name ly an unders tand ing o f t h e fac t t ha t one can , t h r o u g h a consc ious e f f o r t l o o k ob jec t i ve l y and sys temat i ca l l y at all the design c r i te r ia and premises on w h i c h any par t i cu la r s o l u t i o n is based.

Ex is t ing p roduc ts have t o a great e x t e n t been used as examples . These are i nc luded pa r t i cu la r l y where t h e y i l lus t ra te d i f f e r e n t approaches t o the same p r o b l e m and d i f f e r e n t results — and n o t because t h e y are pa r t i cu la r l y good o r bad. There is thus no imp l i ed eva lua t ion in the i r p resen ta t i on .

I w o u l d l ike t o t h a n k those compan ies w h i c h have c o n t r i b u t e d t o the examples by s u b m i t t i n g mater ia l o f var ious k inds . The pho tog raphs w h i c h are n o t acknow ledged were t aken o n m y behal f by F rank S c h m i d t , t o w h o m I am very g ra te fu l .

I t is m y hope t h a t m a n y o f those w h o are invo lved in the e v o l u t i o n o f p roduc t s w i l l f i n d th is b o o k useful w h e t h e r t h e y are engineers o r designers. I also hope t h a t t he b o o k w i l l f i l l a gap in the l i t e ra tu re connec ted w i t h the teach ing o f engineer ing design in the schools o f eng ineer ing. In the t r a d i t i o n a l a p p r o a c h , a mater ia l ob jec t requires a rough d r a w i n g before one can get d o w n t o the necessary speci f ic ca lcu la t ions and de ta i l i ng . A l o t o f t i m e is r i gh t l y used on these essential p rocedures , ye t so o f t e n no one w i l l ques t i on h o w the idea beh i n d any par t i cu la r scheme has emerged. I t is t o o c o m m o n a mis take t o regard the f i r s t idea f o r a design as the o n l y one or even as the best. Last ly I hope t h a t t he b o o k m a y be an i nsp i ra t i on t o indus t r ia l designers in t r a i n i ng and in prac t ice , as i t mus t be i m p o r t a n t f o r designers t o get an idea o f t he phases a c omp l ex p r o d u c t goes t h r o u g h , as wel l as a general v iew o f t he re levant c r i te r ia f o r eva lua t i on .

Esk i ld Tja lve

1 CREATION OF A PRODUCT

1.1 T h e idea o f f o r m 3

1.2 L i f e o f t h e p r o d u c t 6

1.3 Proper t ies o f t h e p r o d u c t 7

1.4 T h e s tep-by-s tep c r e a t i o n o f t h e p r o d u c t 7

1. Creation of a Product

1.1 The idea of f o r m

A very great par t o f our w o r l d consists o f ob jec ts w h i c h have one f u n d a m e n t a l p r o p e r t y , f o r m : i.e. a shape, a cer ta in a r rangement o f parts and an overal l s t ruc tu re . F o r m m a y arise as f o l l o w s (F igure 1 ) :

1 . A n u n c o n t r o l l e d process, where the f o r m depends sole ly on the c o n d i t i o n s o f the env i r o n m e n t , e.g. pebbles, m o u n t a i n ranges.

2. A process c o n t r o l l e d by physica l and chemica l laws as we l l as the c o n d i t i o n s o f the env i ron m e n t , e.g. ice crysta ls , m ica .

3. A process c o n t r o l l e d by genes and the con d i t i ons o f the e n v i r o n m e n t , e.g. l iv ing organisms.

4 . A process c o n t r o l l e d by the wishes o f men or animals and the cond i t i ons o f the e n v i r o n m e n t , e.g. m a n u f a c t u r e d p roduc t s , a beaver's d a m , b i rds ' nests.

N o w t h a t m a n u f a c t u r e d p roduc t s increasingly d o m i n a t e ou r everyday w o r l d — indeed where w h o l e env i ronmen ts are man-made — we need t o analyse more c losely the processes by w h i c h f o r m is d e t e r m i n e d , so t h a t we m a y design ou r e n v i r o n m e n t as m u c h t o ou r l i k i ng as possible.

As a f i r s t a t t e m p t at th is analysis let us examine the valve in Figure 2. The design o f the valve and the parts f r o m w h i c h i t is assembled is as f o l l o w s :

The t w o connec t i ng pieces are hexagonal because one mus t be able t o assemble the valve w i t h an adjustable spanner. The ro ta t i ng n u t under the handweel is also hexagonal so t ha t i t can be t i gh tened w i t h a spanner. The handwhee l is r o u n d because the hand mus t be able t o grasp i t f i r m l y in all pos i t ions . The spindle is th readed because o f its f u n c t i o n , w h i c h is t o t r a n s f o r m the ro ta r y m o v e m e n t (o f

the handwhee l ) i n t o one o f t rans la t i on (of the valve seat). T h e valve seat is annu lar because one mus t be able t o face i t o f f w i t h a m i l l i n g c u t t e r t o make i t f i t t i g h t l y against t he gasket. The inner cav i t y o f the valve is shaped t o fac i l i ta te f l o w . The ou te r f o r m o f the valve consists o f t w o in tersec t ing cy l i nde rs . The c y l i n d e r f o r m is d e t e r m i n e d by the m o u l d f r o m w h i c h the valve hous ing is cast.

S imi la r c o m m e n t s t o the above can be made on the cup and saucer s h o w n in F igure 3 :

T h e c u p and saucer have ro ta t i ona l s y m m e t r y , e i ther because t hey are t h r o w n on the po t te r ' s whee l o r , ( i f t h e y were made in a m o u l d ) s imp l y because cups and saucers t r a d i t i o n a l l y have ro ta t i ona l s y m m e t r y .

T h e cup is cy l i nd r i ca l because a cer ta in appearance was des i red. The cup is smal ler in d iamete r at the base pa r t l y because i t is t hen stackable and p a r t l y f o r reasons o f appearance. The n o t c h in the base o f the cup lets the wa te r d ra in away i f i t is washed (upside d o w n ) in a wash ing up mach ine . T h e shape o f the handle ensures tha t the par t w h i c h is he ld does n o t get t o o h o t w h e n the cup is being used. The edge o f the saucer is t u r n e d up because i t mus t be able t o h o l d l i q u i d sp i l t f r o m the cup .

Even if these t w o examples are a l i t t le s imp l i f i ed t h e y st i l l show c lear ly t h a t the design o f a p r o d u c t and its e lements depends on m a n y d i f f e r e n t fac to rs .

Figure 1 Form can arise in four ways

Creation of a Product 5

Figure 2 The form of the valve is determined by a large number of factors

e.g. m a n u f a c t u r i n g process, f u n c t i o n , ease o f handl ing , appearance and economics . A n o t h e r very i m p o r t a n t f a c t o r , w h i c h we mus t n o t f o rge t , is t he person w h o designs the p r o d u c t . However m a n y requ i rements there are in t he spec i f i ca t ion o f t h e design, there w i l l a lways be r o o m f o r t he designer t o express his ideas and personal j u d g e m e n t .

A n unders tand ing o f t h e fac to rs w h i c h in f luence t he design m u s t be b u i l t on a know ledge o f t h e var ious stages in the l i fe o f the p r o d u c t . In t he f o l l o w i n g pages, t h e r e f o r e , w e w i l l e xam ine a m o d e l o f t h e l i fe o f a p r o d u c t f r o m i n c e p t i o n t o d e s t r u c t i o n , as we l l as a m o r e de ta i led mode l o f t he w a y in w h i c h a p r o d u c t comes i n t o be ing.

Figure 3 Many factors determine the form of a cup (R0rstrand)

6 Creation of a Produc t

1.2 Life of the product

A l l p roduc t s are c rea ted , used and even tua l l y discarded . Le t us, the re fo re , examine a l i t t l e more c losely w h a t happens t o a p r o d u c t be fo re , d u r i n g and af ter use.

When a p r o d u c t is used i t pe r fo rms a process w h i c h br ings a b o u t an ex terna l change f r o m one state t o ano the r . I t is the need f o r th is t rans fo r m a t i o n t h a t has caused t he p r o d u c t t o be c rea ted , f o r examp le :

Scissors: A w h o l e sheet o f paper - paper d i v ided i n t o t w o pieces. Fiie: A b lank w i t h burrs — a b lank w i t h chamfe red edges. Television: A person w i t h a need f o r e n t e r t a i n m e n t and i n f o r m a t i o n — a person en te r ta ined and inf o r m e d . Extruder: Plastic granules — c o n t i n u o u s length o f plast ic p ro f i l e w i t h t he requ i red cross sec t ion .

Before t he p r o d u c t is used the user has b r o u g h t i t f r o m a dealer, w h o in t u r n has b r o u g h t i t f r o m the manu fac tu re r . When i t has e i ther served its purpose, w o r n o u t o r b r o k e n , i t is des t royed .

If these events are arranged in sequence, we can i l lus t ra te the l i fe o f the p r o d u c t as s h o w n in F igure 4 . The s tar t ing p o i n t is the use f o r w h i c h the p r o d u c t is i n tended . The f i r s t phase is the design process in w h i c h possible m e t h o d s o f sa t is fy ing the user needs are e x a m i n e d , and in w h i c h the f i na l l y chosen

p r o d u c t is c o m p l e t e l y spec i f ied . Fo r p r o d u c t s w h i c h are t o be p r o d u c e d in great numbers , the design and cho ice o f p r o d u c t i o n m e t h o d f o l l o w n e x t , b u t f o r the sake o f c l a r i t y th is phase has been le f t o u t in F igure 4 . N e x t comes t he p r o d u c t m a n u f a c t u r i n g process, a f ter w h i c h the p r o d u c t is sold t o the dealer, f r o m w h o m i t is resold t o the consumer . O n l y n o w can t he p r o d u c t f u n c t i o n accord ing t o its i n tended purpose. The l i fe o f t he p r o d u c t ends w i t h dest ruct i o n . Th is process can be act ive, where the p r o d u c t may be c rushed, t aken apar t o f me l t ed d o w n , or passive, where i t rusts, c rumb les or decomposes, etc .

F igure 4 shows t h a t , idea l l y , i n f o r m a t i o n is f ed i n t o t he design process f r o m ail o t he r p roduc t - re l a ted act iv i t ies . E f fec t i ve design is o n l y possible if the designer is aware o f w h a t happens b e y o n d t he d rawing board and in o the r depa r tmen ts . T h u s , the p r o d u c t is spec i f ied d u r i n g t he design process, b u t w i t h requ i rements and wishes f r o m all t he o t h e r stages in m i n d .

I t is i m p o r t a n t t o realise t h a t F igure 4 shows t he general course o f an indus t r i a l l y m a n u f a c t u r e d p r o d u c t . In p r o d u c t s t h a t are designed and made b y the same person the f i r s t t w o processes can be c o m b ined . N o t e also t h a t there m a y be o the r i n p u t t o the design process o the r t h a n i n f o r m a t i o n on need or f u n c t i o n , such as an idea f o r a p r o d u c t o r new c o m p e t i n g p roduc t s . The i n p u t s h o w n in F igure 4 , however , is cons idered the general one , because in t he o t h e r s i tua t ions one st i l l has t o go back and star t w i t h t he need.

Information Of need _

Feed-back information r 1 Γ

DBSIGK/

Specificaéion of Ihe product

/f^iv mater Lais UAKJUrACTUI^E

Object in, first state

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Object in second state

Figure 4 Showing the processes in the life of a product


1.3 Properties of the product

A n y ob jec t ( p r o d u c t , mach ine , or system) possesses character is t ic p roper t ies . Some o f these p roper t ies may be des i red, b u t o thers may be more o r less u n w a n t e d . T h e mos t i m p o r t a n t p r o p e r t y o f all is the p r i m a r y f u n c t i o n o f the p r o d u c t , because it is th is t h a t helps the user in his need. T h e o the r desirable proper t ies m a y be: pleasing appearance, ease o f hand l i ng , sa fe ty , d u r a b i l i t y and re l i ab i l i t y .

Before the p r o d u c t is designed the requ i red proper t ies shou ld be l isted by the designer, perhaps in c o l l a b o r a t i o n w i t h the user. D u r i n g the design per iod w h e n the p r o d u c t is c rea ted , i t is these proper t ies t h a t de te rm ine the decis ions and choices t ha t are made.

U n f o r t u n a t e l y one c a n n o t design a p r o d u c t in such a w a y t ha t the desired p roper t ies are d e t e r m i n e d one af ter t he o t h e r , f o r t h e y are n o t i ndependen t var iables. We f i n d , however , t h a t f ive p roper t ies can be d is t ingu ished f r o m all o thers , in t h a t t oge the r t h e y c o m p l e t e l y de f ine t he p r o d u c t . T h e y are:

For the product as a whole:

For each element:

S t r u c t u r e ( i .e. t he e lements o f t he p r o d u c t and the i r re la t ionsh ip ) F o r m Mater ia l D i m e n s i o n Surface

These f ive p roper t ies are the basic properties. I t is i m p o r t a n t t o emphasise t h a t these are the var iables w h i c h the designer can m a n i p u l a t e , and i t is by successively dec id ing on these t h a t a p r o d u c t is c rea ted . Thus all t he o the r p roper t ies , desirable as we l l as undes i rab le , are der ived f r o m the basic p roper t ies .

T h e a im in designing is t h a t t h e qua l i t ies present in t he f i n i shed p r o d u c t shou ld co r respond t o t he p roper t ies requ i red . As th is a i m , however , is n o t always ach ieved, w e mus t d is t ingu ish be tween the desired p roper t ies and t he real ised ones.

Thus w e can arr ive at a mode l o f t he design process as s h o w n in F igure 5. Th is shows t he step-by-s tep process f r o m the analysis o f t he p r o b l e m t o the f i n i shed p r o d u c t .

In t he in i t ia l analysis stage, t he p r o b l e m is exam ined f r o m all sides. Th is results on the one hand in a conc re te f o r m u l a t i o n o f t he desired f u n c t i o n , and o n the o the r h a n d , in a l ist o f t he desired proper t ies w h i c h c o n s t i t u t e t he c r i t e r ia t h a t mus t make up t h e b a c k g r o u n d f o r t he se lect ion o f so lu t i ons .

N e x t f o l l o w s t he stage o f synthesis , i.e. t he stage in w h i c h the p r o d u c t is c rea ted . Th is is done by r o u g h l y d e t e r m i n i n g step by step o n t he basic p roper t ies o f s t r uc tu re , f o r m , ma te r i a l , d i m e n s i o n , and sur face.

W h e n t he basic p roper t ies are dec ided o n , t he design o f t he p r o d u c t is f i n i s h e d , and i t can be m a n u f a c t u r e d . A f t e r m a n u f a c t u r e the p r o d u c t ex is ts , and possesses some 'realisedproperties., w h i c h h o p e f u l l y are close t o t he 'desi red p rope r t i es ' t h a t were f o r m u lated d u r i n g the in i t ia l analysis.

1.4 The step-by-step creation of the product

The design mode l s h o w n in F igure 5 is a great ly s i m p l i f i e d one , t h a t serves o n l y t o give a general v i ew o f t h e design process. I t c a n n o t be used as a recipe f o r designing a p r o d u c t . I t can , however , be elabo ra ted t o t r y t o achieve th i s . As we are p r i m a r i l y conce rned w i t h t he q u a l i t y o f ' f o r m ' , we w i l l o n l y make the mode l m o r e de ta i led in t he stages where t he basic p roper t ies are la id d o w n .

We can call t he de ta i led m o d e l the product synthesis, as i t shows the i nd i v idua l steps t h r o u g h w h i c h

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Figure 5 Tfie basic properties are the variables which the designer can manipulate. The other properties of the product depend on these

8 Creation of a Product

PROBLEM ANALYSIS

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Figure 6 The product synthesis. A model of the design process showing the stages in the creation of a product

the p r o d u c t is c rea ted , see F igure 6. The b lack a r rows show the t i m e sequence. The p r o d u c t synthesis takes as its s ta r t ing p o i n t the t w o o u t p u t s f r o m the p r o b l e m analysis, namely on the one hand the f o r m u l a t i o n o f the desired f u n c t i o n - the ma in f u n c t i o n (possibly several sub-ord ina te ma in func t ions) on the o ther hand the list of desired p roper t ies , w h i c h can also be descr ibed as c r i te r ia f o r an o p t i m u m p r o d u c t .

In F igure 5 we saw tha t the nex t step is the

d e t e r m i n a t i o n o f the s t ruc tu re . In the p r o d u c t synthesis th is very i m p o r t a n t stage is d i v i ded i n t o a series o f steps, beg inn ing w i t h a d iv is ion o f t he desired f u n c t i o n i n t o sub - func t i ons . T h e n f o l l o w s an e x a m i n a t i o n o f possible means o f real is ing the sub-f u n c t i o n s , a c o m b i n a t i o n o f these i n t o a basic s t ruc tu re and f i na l l y an adap ta t i on i n t o a q u a n t i f i e d s t ruc tu re , where c r i t i ca l parameters are o p t i m i s e d and where the re lat ive a r rangement o f t he e lements is d e t e r m i n e d .

F o r m is t rea ted in t w o paral le l branches, since the t o t a l f o r m and the f o r m o f the c o n s t i t u e n t elements are de te rm ined s imu l taneous l y . The deta i led f o r m o f the e lements inc ludes a spec i f i ca t ion o f mater ia ls , d imens ions and surfaces.

We see f r o m the p r o d u c t synthesis. F igure 6, t h a t the c r i te r ia f o r an o p t i m u m p r o d u c t are used t h r o u g h the w h o l e design process as a gu ide l ine and c o n t r o l f o r each step where a decis ion is t a k e n .

The f o l l o w i n g paragraphs o u t l i n e the ind iv idua l stages in the p r o d u c t synthesis and t yp i ca l examples are g iven.

Main functions

The main function o f a p r o d u c t is the way in w h i c h o u t p u t is de te rm ined by i n p u t . If we conceive the p r o d u c t as a c o m p o u n d system we can discuss func t ions at all levels f r o m the f u n c t i o n o f the to ta l system (main f u n c t i o n , or poss ib ly several paral lel ma in f u n c t i o n s ) t o the f u n c t i o n s o f sub-systems and o f e lements (sub- func t ions ) .

The idea o f f u n c t i o n is a very i m p o r t a n t t o o l f o r analys ing a p r o b l e m i n to a series o f c lear ly f o r m u l a t e d c o m p o n e n t s t h a t express w h a t the p r o d u c t mus t be able t o d o .


Sub-functions and means

By means, we unders tand a s o l u t i o n , i.e. a m e t h o d , a sub-system or an e lement , w i t h w h i c h a given f u n c t i o n can be real ised. The d iv is ion o f the ma in f u n c t i o n i n t o sub - func t i ons and f u r t h e r i n t o sub-sub-f u n c t i o n s , etc takes place a l te rna te ly w i t h the search f o r means t o realise these. One possible p rocedure consists o f ar ranging a so-cal led f u n c t i o n / m e a n s t ree .

F igure 7 shows h o w the f i r s t stages in the f u n c t i o n / means tree f o r an a u t o m a t i c teamaker may l o o k . T h e o r e t i c a l l y the f u n c t i o n / m e a n s tree can be deta i led u n t i l the means become mach ine e lements , or parts o f mach ine e lements . We s top w h e n we have f o u n d means t o the mos t i m p o r t a n t sub - func t i ons .

Basic structure

A s o l u t i o n is achieved by connec t i ng one process f o r each s u b - f u n c t i o n , w h i c h we call the basic s t ruc tu re . T h e basic s t ruc tu re can be expressed in b lock diagrams, w o r k i n g (or basic) d rawings (mach ine symbo l s , h y d r a u l i c , p n e u m a t i c , e lect r ic s y m b o l s , etc) or o the rw ise s i m p l i f i e d d rawings . N o decis ions are made at th is stage as t o ' quan t i t i e s ' such as d imens ions , re lat ive a r rangement e tc . F igure 18 shows d i f f e r e n t basic s t ruc tures o f t he teamaker (see Figure 7 ) .

/ \ FUAJCT/OKJ

MEAKJS

Pass through iêcittn^ sc/ir/fice

Te(Pi process w¿M tea eKtract

Normal tea process Tea process wLtk per/i/iSCOH

Te(Pi process w¿M tea eKtract

Tea process wLtk per/i/iSCOH

Com bene iâter and tea ieavês

mterîea

Γ

/ Co^troL \ ^breNin^ Urne'

I Separate ¿ea\^ from tea Leares

Tea -^yvcpiterl

léaÂj^kyater

fêynove both

tokeaUyi^ \ to keatu^g elemnh /Jeasure

time Measure tea concentration

Kieasi/ire time dependant \ stñte in tke process

Figure 7 The function/means tree for an automatic teamaker

10

Figure 8 Alternative basic structures for an automatic teamaker


Figure 9 Quantified structures for the main elements of a teamaker


Quantified structure

The q u a n t i f i e d s t ruc tu re is one where the i m p o r t a n t parameters o f the ind iv idua l e lements are o p t i m i s e d and spec i f ied , toge ther w i t h the relat ive a r rangement o f the e lements. However , n o t h i n g is y e t dec ided concern ing the f o r m design o f the e lements . D i f f e r e n t q u a n t i f i e d s t ruc tures are s h o w n in F igure 9.

Total form

The to ta l f o r m o f the p r o d u c t is d e t e r m i n e d a l te rna te l y w i t h the f o r m o f the e lements . T h e requ i remen ts o f the t o t a l design depend on the p r o d u c t we are deal ing w i t h . If aesthet ic c r i t e r ia are i m p o r t a n t ( i .e. in cars, boats , cameras, e tc) t he design o f t he e lements mus t be adap ted t o t he t o t a l design.

Figure 10 Suggestions for tfie total form of the teamaker


4 .

Le<^f spring maij be Msed

'Pen

y

1̂ J

Cast

Figure 11 S/<etches made in connection with the detail design elements of the teamaker

If techn ica l and e c o n o m i c c r i te r ia are w h a t mat te rs mos t (i.e. ca rbu re t to rs , gearboxes, satel l i tes, etc) t he design o f the e lements mus t take precedence over the t o ta l design.

Form of the elements

The f o r m design o f the ind iv idua l e lements is made at the deta i l design stage o f the p r o d u c t . The var ious cons idera t ions o f the f o r m o f the f u n c t i o n a l areas make a good s tar t ing p o i n t f o r th is stage. The c r i te r ia w h i c h ma t te r at th is stage are p r i m a r i l y d e t e r m i n e d by f u n c t i o n , s t rength and m a n u f a c t u r i n g me thods .

Typ i ca l act iv i t ies at th is stage are, f i r s t o f a l l , ca l cu la t i on , ske tch ing and d raw ing . Free-hand sketches done in a q u i c k and l igh t t echn ique are

e x t r e m e l y usefu l , see Figure 1 1 . G radua l l y , as the f o r m o f the e lements is se t t led , the sketches are rep laced by layou ts , p repared w i t h a d raw ing mach ine , and scale drawings.

T h e f ina l design o f each e lement requires decis ions on ma te r ia l , d imens ion , surface, to lerance and p r o d u c t i o n t e c h n o l o g y .

The e lements o f the p r o d u c t are speci f ied in w o r k i n g drawings w h i c h express f o u r o f t he f u n d a men ta l p roper t ies , f o r m , ma te r i a l , d imens ion and sur face, as we l l as f u r t h e r i n f o r m a t i o n such as quan t i t ies t o be p r o d u c e d , possible m a n u f a c t u r i n g process, n u m b e r o f the d r a w i n g , da te , etc . The f i f t h f unda men ta l p r o p e r t y , the s t ruc tu re , is speci f ied in assembly drawings w h i c h s h o w h o w the c o m p o n e n t e lements are t o be assembled, see Figure 12. The f i n i shed teamaker is s h o w n in F igure 13.


Ί5)

Figure 12 Assembly drawing and working drawing

Product syntfiesis

Each phase in the p r o d u c t synthesis br ings the designer nearer his goal - the f i n i shed p r o d u c t . In spi te o f the chang ing con ten ts o f the phases t h e y all show a t yp i ca l course :

1 . The search f o r so lu t i ons , 2. E x a m i n a t i o n o f the so lu t i ons , 3. Eva lua t ion and cho ice o f so lu t i ons f o r f u r t h e r

w o r k .


Figure 13 The finished teamaker (The Laboratory for Engineering design. The Technical University of Denmark)

Th is course is i l l us t ra ted in F igure 14 , where the n u m b e r o f so lu t i ons is s h o w n as a f u n c t i o n o f t i m e . Each peak cor responds t o a phase in the p r o d u c t synthesis .

T h e search f o r so lu t i ons is car r ied o u t b y genera t ing ideas e i ther i n t u i t i v e l y o r sys temat i ca l l y , the m o s t app rop r i a te m e t h o d s depend ing on the phase. The a im in seeking m a n y so lu t i ons in a given phase is t o exp lo re the 'space' c reated by the great n u m b e r o f t heo re t i ca l l y possible so lu t i ons . I t is se ldom possible t o exam ine all so lu t i ons , as t h e y are usual ly i nnumerab le . B u t t he ' s o l u t i o n space' shou ld st i l l be e x a m i n e d t h o r o u g h l y so t h a t all t he m a i n types o f s o l u t i o n are i n c l u d e d . O n l y t hen we can say w i t h reasonable ce r t a i n t y t h a t we can choose the best s o l u t i o n .

The eva lua t ion o f the so lu t i ons is made o n the basis o f c r i te r ia w h i c h vary w i t h the phase and the degree o f deta i l in t he so lu t i ons . A n i n t u i t i ve evalua t i o n may thus be su f f i c i en t in t he ear ly phases, wh i l e later o n i t m a y be necessary t o app l y qu i t e a n u m b e r o f m u t u a l l y w e i g h t e d c r i t e r i a .

T h e f i na l resul t — the p r o d u c t — thus depends o n t w o f u n d a m e n t a l l y d i f f e r e n t fac to rs , f i r s t l y o n the ideas t h a t are b o r n , and second ly on the c r i t e r i a t h a t dec ide w h i c h ideas are chosen. A closer analysis o f t he idea o f f o r m can be made f r o m these t w o po in t s o f v iew. Thus the n e x t chap te r deals w i t h the m e t h o d s t h a t can be app l ied in searching f o r f o r m ideas, w h i l e Chap te r 3 ' F o r m F a c t o r s ' is a b o u t t he fac to rs t h a t make up the b a c k g r o u n d f o r t he se lec t ion c r i t e r i a .

Number of solutionis

£xciniLhation ofsoLiAtcoMS

T^me

Figure 14 The search for and examination of solutions, evaluation and choice are a characteristic sequence in the product synthesis

2 METHODS USED IN FORM DESIGN

2.1 L i m i t a t i o n s 19

2.2 S t r u c t u r e v a r i a t i o n 21

2.3 F o r m v a r i a t i o n 4 8

17

2. Methods Used in Form Design

2.1 Limitat ions

The f ina l decis ions o n a p r o d u c t ' s f o r m n o r m a l l y take place in t h e last phases o f t he design process, b u t i t is i m p o r t a n t t o realise t h a t be fo re th i s , t he designer has a l ready been re f lec t ing and m a k i n g decis ions t h a t have a f u n d a m e n t a l i n f l uence o n t h e f o r m . In t h e prev ious chap te r (sect ion 1.4) we saw an examp le o f th is . Let us, however , cons ider a n u m b e r o f examples w h i c h m o r e d i r e c t l y i l l us t ra te t he i m p o r t a n c e o f t he ear ly decis ions o n t he f o r m o f t he p r o d u c t .

T h e ma in f u n c t i o n o f t he p r o d u c t — establ ished d u r i n g t he f i r s t phase o f p r o d u c t synthesis - has a cruc ia l i n f luence o n the t y p e o f p r o d u c t , e.g. w h e t h e r i t is a mach ine o r a t o o l . T w o p roduc t s w i t h d i f f e r e n t ma in f u n c t i o n s w i l l t he re fo re be so d i f f e r e n t t h a t i t is imposs ib le t o create one ' in b e t w e e n ' - t h e y are s imp l y f u n d a m e n t a l l y d i f f e r e n t . F igure 15 shows an examp le o f t h i s , name ly a ca l cu la to r and an abacus.

T h e ca l cu la to r f u l f i l l s t h e same need f o r an European as t h e abacus f o r a Chinese.

T h e w a y in w h i c h t h e ma in f u n c t i o n is b r o k e n d o w n i n t o s u b - f u n c t i o n s , as we l l as t h e means chosen , t o sat is fy t h e s u b - f u n c t i o n s is jus t as i m p o r t a n t f o r t he design as t h e m a i n f u n c t i o n . Th is can be i l l u s t ra ted b y a c o m p a r i s o n o f t w o p r o d u c t s w i t h t he same m a i n f u n c t i o n b u t w i t h a d i f f e r e n t basic s t ruct u r e .

F igure 16 shows t w o d i f f e r e n t jacks, b o t h w i t h the ma in f u n c t i o n - t o t r a n s f o r m a r o t a t i ona l manua l m o v e m e n t i n t o a very p o w e r f u l ver t ica l one . T h e f o r m o f t he t w o jacks d i f fe rs f u n d a m e n t a l l y , because d i f f e r e n t means have been used t o real ize t h e i nd i v idua l sub f u n c t i o n s , i.e. the basic s t ruc tu re is d i f f e r e n t . We can also no te t h a t t he f o r m o f one c a n n o t be g radua l l y changed i n t o t he f o r m o f t he o the r .

Figure 15 Desk calculator arid Japanese abacus or counting frame. The two products fulfil the same need, but the main function is different (Desk calculator reproduced by courtesy of Canon)

19

2 0 Methods used in form design

Figure 16 Two car jacks having the same main function (i.e. similar input and output) but different basic

structures

Basic s t r u c t u r e

ψ

-o

Figure 17 Two valves with the same basic structure but with different quantified structures. The lower illustration shows how one structure can be gradually changed into the other

T h e q u a n t i f i e d s t ruc tu re br ings us t o a level in p r o d u c t synthesis where w e can move g radua l l y f r o m one s o l u t i o n t o ano the r . In F igure 17 t h e t w o valves have d i f f e r e n t q u a n t i f i e d s t ruc tu res b u t t h e same basic s t r uc tu re , i.e. f r o m the p o i n t o f v iew o f f u n c t i o n t h e y c o n t a i n t he same e lements . T h e y are d is t ingu ished b y t he d i f f e r e n t f o r m design o f t h e e lements and by t h e d i f f e r e n t angle o f t he sp ind le and the handwhee l . T h e w a y in w h i c h t h e f o r m design o f t h e t w o valves can be m o d i f i e d , so t h a t w e can move gradua l l y f r o m one t o t he o the r , is also i l l us t ra ted .

F o r m synthesis m e t h o d s a i m t o cover t h e w h o l e range o f design so lu t ions . We have seen t h a t f o r a chosen basic s t ruc tu re the f o r m design can be changed s m o o t h l y f r o m one s o l u t i o n t o ano the r . T h e m e t h o d s f o r f o r m synthesis can the re fo re be na tu ra l l y descr ibed as va r i a t i on me thods where some charac-

Methods used in form design 21

2.2 Structure variation

Tfie structure variation method

Cons ider t h e th ree co f fee makers s h o w n in F igure 18. T h e y all w o r k o n t he same p r i nc ip le (i .e. w i t h a s im i la r basic s t r u c t u r e ) . B u t w h y are t w o o f t h e m a l i ke , w h i l e t he t h i r d one is q u i t e d i f f e ren t? T h e answer lies in the q u a n t i f i e d s t ruc tu re .

Figure 18 Three different coffee makers with the same basic structure. The shape of the top two products is a/most idéntica/. Why is the one below different?

(Courtesty of Melitta, NG Electric, Braun)

te r i s t i c parameters are var ied in such a w a y t h a t t h e w h o l e s o l u t i o n space is covered . T h e ques t i on o f w h i c h parameters can be p r o f i t a b l y var ied w i l l be e x a m i n e d in t he f o l l o w i n g chapters , where the m e t h o d s are re la ted t o t h e last phases in p r o d u c t synthes is , name ly t he q u a n t i f i e d s t r uc tu re , t he t o t a l f o r m and t h e f o r m o f t h e e lements .

22 Methods used in form design

In t he f i r s t t w o the re lat ive a r rangement o f t h e c o m p o n e n t e lements is s imi la r , w h i l e in t he last one i t is d i f f e ren t . T h e relat ive a r rangement o f the c o m p o n e n t e lements is an i m p o r t a n t fea ture o f a q u a n t i f i e d s t ruc tu re . A n o t h e r i m p o r t a n t fea tu re is the d imens ions o f t he par ts , in th is case t he sizes o f the conta iners and t he d is tance be tween these.

T h e relat ive a r rangement and the d imens ions o f t he c o m p o n e n t e lements can be used as va r ia t i on parameters in the search f o r design so lu t ions . Th is m e t h o d can be cal led ' the s t ruc tu re va r ia t ion m e t h o d . ' The greatest e f fec t is achieved i f the ind iv idua l so lu t ions are i l l us t ra ted (poss ib ly m o d e l l e d in th ree d imens ions) in a t echn ique where all superf l uous detai ls are le f t o u t . In th is w a y one saves t i m e in the f o r m u l a t i o n o f t he so lu t i ons as we l l as c l a r i t y w h e n c o m p a r i n g t h e m .

F igure 19 shows the basic s t ruc tu re f o r co f fee makers , toge the r w i t h h o w a n u m b e r o f q u a n t i f i e d s t ruc tures created by va r i a t i on o f t he re lat ive arrangem e n t and o f t he d imens ions o f t he e lements .

F igure 20 shows examples o f t yp i ca l co f fee makers . I t demons t ra tes h o w a c o m m o n q u a n t i f i e d

s t ruc tu re f o r any t w o p roduc t s gives a c o m m o n design character , wh i l e d i f f e r e n t q u a n t i f i e d s t ruc tu res p roduce w i d e d i f fe rences in the design.

T h e s t ruc tu re va r i a t i on m e t h o d is an easy m e t h o d o f generat ing ideas f o r a l te rna t ive s t ruc tu res . The m e t h o d is based on the v iew t h a t a n u m b e r o f suggested so lu t ions are needed before a s o l u t i o n can d e f i n i t e l y be character ised as g o o d . T h e m e t h o d has been t r i e d in d i f f e r e n t p ro jec t s i tua t ions , and i t can be app l i ed at m a n y levels, e.g. in b o t h t he b u i l d i n g up o f t he t o t a l system and in t h e c rea t i on o f smal l sub-systems.

Q u a n t i f i e d s t ruc tu re can be used f r o m t w o po in t s o f v i ew , w h i c h d i f f e r in w h e t h e r the f u n c t i o n a l c o n nec t i on be tween the e lements is i nc luded or n o t . I f these f u n c t i o n a l connec t i ons are i gno red , t h e s t ruct u r e va r ia t i on m e t h o d gives a n u m b e r o f suggestions f o r a very rough c o n s t r u c t i o n o f t he p r o d u c t . I f t he f u n c t i o n a l connec t i ons are i n c l u d e d , we get a d e f i n i t e f u r t h e r d e v e l o p m e n t o f t h e basic s t r uc tu re , w i t h the a im o f o p t i m i s i n g and spec i f y i ng t h e parameters invo lved . Th is is s h o w n by the examples given in the f o l l o w i n g paragraphs.

Q U A N T I F I E D STRUCTURES

V a r i a t i o n of r e l a t i v e a r rangement

w a Figure 19 Quantified structures for coffee ma/<ers

23

Figure 20 Various types of coffee makers. See a/so quantified structures in Figure 19 (Courtesy of Siemens, Krups, Me/itta, Ptii/ips, and Braun)


sor t ing o f t he so lu t ions acco rd ing t o such c r i te r ia as space, o p e r a t i o n and appearance.

F igure 21 shows a n u m b e r o f q u a n t i f i e d s t ruc tures f o r a vacuum cleaner, t oge the r w i t h the relat ive a r rangement o f t he th ree ma in e lements . The func t i ona l c o n n e c t i o n be tween the e lements is n o t i nd i ca ted . F igure 22 shows some m o d e r n vacuum cleaners, where we can see h o w great ly the relat ive a r rangement o f t he e lements in f luences the design.


Variatior^ of re la t i ve ar rangement

SYMBOLS

t o r jTTI Mote

1 S I Dust conta iner

Mouthpiece

e t c

Μ

M l .

S. s—

Μ

Μ Μ

Figure 21 Quantified structures for vacuum cleaners

Structure variation of tfie main elements

The e lements t h a t mos t in f luence a p r o d u c t ' s f o r m design are, o f course, the ma in ones. We may therefo re conven ien t l y app ly the s t ruc tu re va r ia t ion m e t h o d t o a f e w o f the ma in e lements o f t he p r o d u c t , in o rde r t h a t a f i r s t survey o f the possib i l i t ies f o r t he design may be car r ied o u t . The sketches or models made at th is stage give a backg round f o r a f i rs t rough

2 5

Figure 22 Vacuum cleaners with different quantified structures. (See also Figure 21). (Courtesy ofNilfisk and Miele)


Let us n o w see h o w the s t ruc tu re va r i a t i on nnethod can be app l ied t o a m ic roscope . The basic s t ruc tu re o f t he mic roscope is character ised by t he lenses and image planes i nvo l ved . T o d e t e r m i n e t h e der ived s t ruc tu re , one needs i n f o r m a t i o n on the size and foca l length o f t he lenses, t he d is tance be tween t h e m and the i r re lat ive ar rangement . F igure 2 3 shows q u a n t i f i e d s t ruc tures based on va r ia t i on o f the relat ive ar rangement o f the t ube and the ob jec t p lane in re la t i on t o t h e tab le .

The f u n c t i o n a l connec t i ons be tween t he e lements (e.g. the d i r e c t i o n o f t he rays and focussing) are n o t i nc luded in t he q u a n t i f i e d s t ruc tu res , b u t t h e y can

be d r a w n very q u i c k l y . T h e t w o mic roscopes in F igure 24 are c o n s t r u c t e d w i t h d i f f e r e n t q u a n t i f i e d s t ruc tu res , w h i c h can be c lear ly seen f r o m t h e i r ve ry d i f f e r e n t designs.

O f t e n i t is possible t o use y e t ano the r va r i a t i on parameter , name ly the n u m b e r o f each o f t h e con s t i t u e n t t ypes o f e lement . In p r i nc ip le a va r i a t i on o f t he n u m b e r belongs t o the basic s t r u c t u r e , b u t in cases where an e lemen t can be d i v i ded i n t o several or d o u b l e d — w i t h o u t a l te r ing t he charac ter o f t h e basic s t ruc tu re — the n u m b e r m a y w i t h equal r i gh t be var ied under t he q u a n t i f i e d s t r u c t u r e .

QUANTIFIED STRUCTURES

Variation of relat ive a r rangement

BASIC STRUCTURE

•4

1«^ I

4 Γ

Figure 23 Quantified structures for a microscope

27

Figure 24 Microscope with different quantified structures. (Courtesy of Olympus and Monolynx)


In F igure 2 5 , no te t h a t t he range o f so lu t i ons is na r rowed cons iderab ly due t o t he fac t t h a t all t he wheels m u s t be o n t he same level , and t h a t n o elem e n t m a y lie be l ow th is level.

In F igure 2 5 , no te also t h a t t he key t o t he systema t i c a r rangement cover ing the w h o l e s p e c t r u m o f so lu t i ons lies in the smal l f r a m e d f igures. These

QUANTIFIED STRUCTURFi^ SYMBOLS O Wheel

lEl Engine

V a r i a t i o n o f : R e l a t i v e a r r a n g e m e n t - N u m b e r ! Operator

ELEMENTS ON ONE LEVEL

2 Wheels

OOdl lH ] OOEll OiOSl O M O

OÍEO O m o Jooia isioo

OMO Β ΟΪΟ ?! EOG lOO Figure 25 Quan tified structures for road rollers

Figure 25 shows possible q u a n t i f i e d s t ruc tures f o r road rol lers, where the va r ia t i on parameters are the relat ive ar rangement and t he n u m b e r o f the e lements . The elements we examine are: wheels, engine and pos i t i on o f the opera to r . O n l y road rol lers b u i l t o n the t r a d i t i o n a l p r i nc ip le , where ro l l i ng wheels and t r anspo r t wheels are ident ica l are cons idered .

2 9

3 Wheels

Id OOiEQO

4 Wheels

)?ΟΪΕθΟ

)?OIñlO

O O ο Ϊ ε ι ο

Figure 25 (continued)

3 0

ELEMENTS ON TWO LEVELS

2 Whee ls

...|... - I !•·· o m o m o o

o o f οίο ο ίο ί ο o 3 Wheels

OOOE\ OÖmO OmOO ΞΟ

doof οοίο οοϊο̂ cíoo Ι οοο

Ä 4 Wheels

o o ö o J m

oooo Ε · · ·

o o o o Figure 25 (continued)

31

E L E M E N T S ON TWO LEVELS

2 Wheels

• m l

OO O

i. Wheels

o o o o o o o

ELEMENTS ON THREE LEVELS

MM.

2 Wheels ..|„ / E l ) É)" \ S o l

Í Wheels

o o o o

3 Whee ls

OOO

3 Wheels

O

) 0 0

\ O O o /



Figure 26 Road rollers. (See also Figure 25)

f igures express t he levels o n w h i c h the e lements lie a reasonable n u m b e r ( f o u r , in th i s case) o f categor ies, in re la t ion t o t he ea r th . O f course an e lement (e.g. When a given s t ruc tu re is chosen f o r c loser e x a m i n -t h e engine) m a y l ie o n a level be tween t h e ones w e a t i o n one m u s t s t i l l feel f ree t o va ry t h e a r rangemen t are cons ider ing , b u t as t he possib i l i t ies are obv ious l y o f the e lements , a l t hough w i t h i n n a r r o w l im i t s , i nnumerab le w e begin by d i v i d i ng t he p r o b l e m i n t o F igure 2 6 shows some m o d e r n ex is t i ng road ro l lers .

3 3



Range of solutions for two and three elements

I t is necessary t o ask ' H o w m a n y q u a n t i f i e d s t ructures is i t real ist ic t o d r a w up , and is i t possible t o get a clear v iew o f the w h o l e range o f s o l u t i o n ? ' In m a n y cases th is can be done i f o n l y the mos t i m p o r t a n t e lements are inc luded as a basis f o r the var ia t ions . The possib i l i t ies f o r t w o and three e lements are examined be low .

I f we examine the relat ive a r rangement o f t w o e lements o f a p p r o x i m a t e l y equal size we can d r a w up the possibi l i t ies s h o w n in F igure 27 . Obv ious l y

the angle o f the t w o e lements can be var ied g radua l l y , b u t the range o f so lu t ions can be i l l us t ra ted by the angles s h o w n .

The re lat ive a r rangement o f th ree e lements o f t he same o rde r o f size can be sub jec ted t o t he same con s iderat ions. F igure 2 8 shows a n u m b e r o f possib i l i t ies at the s h o w n level o f de ta i l . The great n u m b e r o f so lu t i ons t h a t emerge t h r o u g h a p e r m u t a t i o n o f th ree d i f f e r e n t e lements in each o f the pos i t ions s h o w n w i l l a lways be q u i c k l y l i m i t e d w h e n w o r k i n g on a speci f ic p r o d u c t . A n examp le o f th is is s h o w n in the examp le o n page 4 2 .

ARRANGEMENT OF TWO ELEMENTS:

0

O

Remember:

i.e. one inside the o t h e n

Figure 27 Possibilities for the relative arrangement of two elements

3 5

Figure 28 Possibilities for the relative arrangement of the three elements


boat being used as the source o f energy f o r t he p u m p . As the boa t rocks , a p e n d u l u m o n a ver t ica l axis swings f r o m side t o side and th is dr ives a p i s ton p u m p . The inset o f F igure 2 9 shows the basic s t ruc tu re .

F igure 2 9 also i l lust rates t he fac t t h a t there are m a n y possible var ia t ions , as the re lat ive a r rangement and the d imens ions can be changed c o n t i n u o u s l y . I t is t he re fo re i m p o r t a n t t o make t h e var ia t ions at t h e co r rec t stage, w h i c h means t h a t t he n u m b e r o f elements cons idered mus t no t be t o o great (less i m p o r t a n t ones are k e p t f o r la te r ) , and t h a t t h e parameters mus t be var ied in su i tab le steps. Thus each suggested s o l u t i o n ske tched mus t be t h o u g h t o f as represent ing a ca tegory o f so lu t i ons . Later , w h e n choos ing t he best suggest ions, t he ind iv idua l categor ies m a y be exam ined m o r e c lose ly .

Structure variation in connection witfi function

The f u n c t i o n a l c o n n e c t i o n be tween the mos t i m p o r t ant e lements is expressed in t he basic s t r uc tu re , mos t o f t en in some sor t o f ske tch show ing the p r inc ip le o f the design, where c o m m o n l y accepted symbo ls f o r k n o w n e lements (mach ine , h y d r a u l i c , pneuma t i c , e lect r ic symbo ls , etc) are used. So long as th is ske tch expresses the basic s t ruc tu re i t is e x e m p t f r o m any de f i n i t e d imens ions or f o r m , bu t i t may be t he s ta r t ing p o i n t f o r a series o f q u a n t i f i e d s t ruc tu res bu i l t on the s t ruc tu re va r ia t ion m e t h o d w i t h t he relat ive a r rangement and d imens ions as parameters f o r each separate e lemen t in t he basic s t ruc tu re .

Figure 29 shows the q u a n t i f i e d s t ruc tu re f o r a bal ing p u m p in tended f o r keeping a m o o r e d boa t e m p t y o f wa te r by the r o c k i n g m o v e m e n t o f t he

37

QUANTIFIED STRUCTURES BASIC STRUCTURE

Pendulunn Water out

O '

7777777

Piston p u m p ] ^

Water in

RELATIVE ARRANGEMENT

777Z7Z7

CUD

H D -CID

////////'

DIMENSIONS

V

7777777

to v a r y : Α , Β , L , D , V :

-CID; - f e ///////

O'

77777

o

77777 Ώ

Figure 29 Quantified structures for a baling pump

Var iat ion of: Relat ive a r r a n g e n n e n t - Dinnensions


Figure 3 0 shows a n u m b e r o f q u a n t i f i e d s t ruc tu res f o r a gear, d r a w n up o n the basis o f the basic s t ruc tu re i l l us t ra ted in t he inset. Here t h e re lat ive a r rangement and the d imens ions are n o t independ e n t l y var ied . Whe ther i t is useful t o keep the t w o parameters separate d u r i n g the search f o r so lu t i ons depends o n t he na tu re o f the p r o b l e m , a fac t w h i c h is also ev ident f r o m the o the r examples in th is

sec t ion . F igure 31 shows examples o f s t ruc tu re va r ia t i on f o r a labe l l ing mach ine . T h e t o p i l l u s t r a t i on shows q u a n t i f i e d s t ruc tu res f o r f o u r ex is t ing labe l l ing mach ines, and a n u m b e r o f o the r possib i l i t ies are s h o w n b e l o w . F ina l l y , F igure 3 2 shows some q u a n t i f i ed s t ruc tu res f o r an excavator , and F igure 3 3 demons t ra tes h o w th ree o f these are e m p l o y e d in ex is t i ng excavators .


Variation o f : Relative ar rangement - D i m e n s i o n s

BASIC STRUCTURE

Ψ777Λ

v////\ ν////λ Z77/A

4 -

Figure 30 Quantified structures for a gear

3 9

QUANTIF IED STRUCTURES

Variation o f : Re la t ive ar rangement - Dimensions

BASIC STRUCTURE

Rol l of labe ls Motor

Label

M j Roll for ^̂?¿>C s u p p o r t i n g ( 9 ) s t r i p I

U e x i s t i n g l a b e l l i n g m a c h i n e s :

Other p o s s i b i l i t i e s

0 ® ( M )

Figure 31

Θ ®

Ms)®® Figure 31 Quantified structures for a labelling machine

4 0


V a r i a t i o n p a r a m e t e r s

A r r a n g e m e n t

D i m e n s i o n s

B A S I C STRUCTURE

Figure 32 Quantified structures for an excavator

41

Figure 33 Excavators wit/i different quantified structures. (See a/so Figure 32)


A coherent example: a tea-maker

In th is sect ion we w i l l examine h o w the t w o s t ruc tu re va r ia t ion me thods can be e m p l o y e d successively. For examp le , cons ider a tea-maker , where bo i l i ng wate r is p o u r e d o n t o tea leaves, and where t he tea brews before the leaves are removed f r o m the f i n i shed tea. We imagine t h a t we have reached a stage in the design w o r k where d i f f e r e n t basic st ructures have been cons idered , so t h a t t h e q u a n t i f i e d s t ruc tu re mus t be cons idered .

As a f i r s t approach t o the q u a n t i f i e d s t ruc tu re we may l o o k at t he re lat ive a r rangement o f t he th ree ma in e lements : a con ta ine r f o r c o l d wa te r , one f o r tea t h a t is b rew ing , and f i n a l l y one f o r t he f i n i shed tea , where the la t ter m a y perhaps be a t r a d i t i o n a l t eapo t . The m a n y possib i l i t ies i l l us t ra ted in F igure 28 are reduced since s t ruc tu res w h i c h are s y m m e t r i c a l r o u n d a ver t ica l axis are iden t i ca l . T h e relat ive ar rangements are s h o w n in F igure 3 4 . N o t e h o w the s imple sketches c o n t r i b u t e t o m a k i n g sys temat ic va r ia t i on easy. Va r ia t i ons can be made by d r a w i n g f r o m one s o l u t i o n t o ano the r .

A m o n g t h e so lu t i ons in F igure 3 4 are some w h i c h can be exc luded o n t he basis o f c r i t e r i a such as hand l i ng ( the t e a p o t o u g h t n o t t o be inside t he o the r con ta iners ) and quest ions o f space (e.g. t he th ree e lements in a r o w can be o m i t t e d ) .

T h e nex t step in dec id ing o n m o r e de ta i led q u a n t i f i e d s t ruc tu res consists o f c o n n e c t i n g t h e usable s t ruc tu res in F igure 3 4 w i t h a basic s t r uc tu r e w h i c h i t is assumed has been chosen be fore t h e re lat ive a r rangement o f t h e e lements was cons ide red . T h e inset in F igure 3 5 shows a rough ske tch o f a suggest ion f o r a basic s t r uc tu re . T h e m a i n i l l u s t r a t i o n shows t w e n t y d i f f e r e n t q u a n t i f i e d s t ruc tu res expressing the re lat ive a r rangement o f t he e lements a n d the f u n c t i o n a l re la t ionsh ip be tween t h e m .

I t is possib le, in t he l igh t o f t h e d iagrams in F igure 3 5 , t o d iscard some s t ruc tu res . T h e fac to rs t h a t can be used as c r i t e r ia are: pr ice ( c o m p l e x i t y ) , appearance, hand l i ng a n d ef fect iveness. T h e f i na l cho i ce o f s t r uc tu re can o n l y be safely made a f te r cons ide r ing t he design possib i l i t ies f o r some o f t he m o s t p r o m i s i n g s t ruc tu res .

4 3


V a r i a t i o n of r e l a t i v e a r r a n g e n n e n t

SYMBOLS

[K\ B o i l e r

B r e w i n g vessel

(ψ) Teapot

ra g l ® Θ ' SS-

®

^ ^ i ^ ^msi m Ί 2 . 3 &

SS TU 3Σ

" i^

8

ffi.

1®! " 2 IIL E l

4 3

Figure 34 Relative arrangement of boiler, brewing vessel and teapot for design of the teamaker

4 4

Q U A N T I F I E D S T R U C T U R E S

V a r i a t i o n o f relat ive a r rangement

\ — I

Ο

ΙΟ

B A S I C S T R U C T U R E

tÉ κ tÉ

Heat ing e lemen t w h i c h forces the bo i l i ng wa te r i n t o the b rew ing vessel. A f t e r b r e w i n g , a rema in ing a m o u n t o f wa te r is b o i l e d , w h e r e b y the tea is f o r ced i n t o the t eapo t

Ti ΐ

7 ^

1^ }

I 2 2 . - 1 21-2.

Figure 35 Basic structure arid twenty quantified structures for an automatic teama/<er. (The figures refer to Figure 34)

4 5



Structure modelling

When va ry ing t he s t ruc tu re i t is a lways necessary t o visualise the possib i l i t ies. Diagrams w i t h s i m p l i f i e d symbo ls are su i tab le f o r th is purpose. Th is can be seen f r o m the prev ious examples in th is sec t ion . Mak ing th ree-d imens iona l models m a y , however , also be re levant . F igure 3 6 shows some s t ruc tures f o r a tea maker mode l l ed w i t h s imple t o y b r i cks . (See also F igure 3 4 ) .

Where more c o m p l e x s t ruc tu res are being c o n s idered, sketches are n o t su f f i c i en t , and In such cases th ree-d imens iona l m o d e l l i n g is t he o n l y poss ib i l i t y . A t yp i ca l th ree-d imens iona l mode l is s h o w n in F igure 3 7 , where q u a n t i f i e d s t ruc tures f o r a test t ube f i l l i n g mach ine are s h o w n . (Fo r a more deta i led

desc r i p t i on o f t he mach ine see page 5 6 ) . As t he in t e n t i o n o f such a mode l is t o f i n d o u t w h i c h re lat ive ar rangements o f t he e lements are real is t ic , t he m o d e l mus t be cons t ruc ted in such a w a y t h a t t he e lements can be q u i c k l y m o v e d t o new pos i t i ons . Fo r th is purpose br icks o f po l ys t y rene are e x t r e m e l y use fu l , p a r t l y because t h e y are easy t o carve, and p a r t l y because the i r l igh t w e i g h t a l lows a b r i ck t o be he ld fast in any pos i t i on by jus t be ing pressed d o w n o n t o a t h i n sp ike . N o t e here t h a t we are t a l k i n g a b o u t s t r uc tu re mode ls and n o t a b o u t f o r m mode ls . Th is means t h a t t he c o m p o n e n t e lements o n l y need t o be m o d e l l e d by the space t h e y w i l l o c c u p y and n o t by t he i r f o r m detai ls . (See also chap te r 5, w h i c h also deals w i t h th ree-d imens iona l s t ruc tu re mode l s ) .

Figure 36 Mal<ing three-dimensional models of quantified structures for a teamaker with the aid of toy bricks. (See also Figure 34)

4 7

Figure 37 Three-dimensional models of quantified structures for a test tube filling machine. On an evaluation of space and handling conditions the best structure may be chosen


2.3 Form variation

The idea of functional surfaces

In t he prev ious sect ion i t was s h o w n h o w t h e basis f o r t he fornn design o f a p r o d u c t is la id d o w n by choos ing t he q u a n t i f i e d s t ruc tu re . Once th is cho ice has been made in a speci f ic p ro jec t t h e actual f o r m design w o r k can star t . As t he discussion o f p r o d u c t synthesis showed , there are t w o aspects o f t h e design t h a t mus t be t rea ted c o n c u r r e n t l y , name ly the t o t a l f o r m o f t he p r o d u c t and t he f o r m o f t he i nd i v idua l e lements. T h e me thods t h a t may be e m p l o y e d f o r these t w o act iv i t ies are b r o a d l y s imi lar . So in t h e f o l l o w i n g pages, where we have used examples o f e lemen t design, the m e t h o d s demons t ra ted can be t rans fe r red d i r ec t l y t o the t o t a l design and vice versa.

H o w can one make a s ta r t o n t h e f o r m design o f a spec i f ic e lement? We mus t ask ourselves w h a t i t is t h a t characterises t h e e lemen t in ques t i on . T h e elem e n t is a par t o f b o t h a basic s t ruc tu re and o f a q u a n t i f i e d s t r uc tu re . We can the re fo re say t h a t t h e e lement has been de f i ned o n l y by its f u n c t i o n and by its f u n c t i o n a l re la t ionsh ip t o its su r round ings . T h e s ta r t ing p o i n t o f the f o r m design mus t consequen t l y be t o f o r m u l a t e t h e f u n c t i o n s the e lemen t mus t perf o r m . Therea f te r one can ske tch t he mos t i m p o r t a n t surfaces - o r f u n c t i o n a l surfaces - and f r o m these the rest o f t he e lemen t m a y be designed.

In th is b o o k a f u n c t i o n a l surface is t a k e n t o mean a surface t h a t has an act ive f u n c t i o n d u r i n g use - f o r examp le , t he s lo t in t he head o f a screw, t he area o f i m p a c t o n t he head o f a h a m m e r ; t he surface o f a cha i r seat; t he cogs o n a whee l , e tc .

We n o w examine t he c o n n e c t i o n be tween t he f u n c t i o n a l surfaces and t h e f o r m . For examp le , let

Figure 38 Two different bottle openers with apparently nothing in common

Figure 39 The functional surface for the two bottle openers

US select a s imp le e lemen t - a b o t t l e opener . F igure 3 8 shows t w o t ypes o f opener w h i c h d o n o t appear t o have m u c h in c o m m o n ; however , t h e f u n c t i o n a l surfaces are a lmos t i den t i ca l , see F igure 3 9 . A b o t t l e opener possesses th ree f u n c t i o n a l surfaces as s h o w n . T h e d i f f e rence be tween t h e t w o t ypes i l lust r a t e d consists in t he d i f f e r e n t spacial a r rangemen t o f t he mater ia l c o n n e c t i n g t h e f u n c t i o n a l surfaces.

We can t he re fo re i d e n t i f y t w o steps in t he design o f an e lemen t , o n t he one hand d e t e r m i n i n g t h e f u n c t i o n a l surfaces and , o n t h e o the r , dec id ing h o w these w i l l be c o n n e c t e d toge ther . As a l ready ment i o n e d . F igure 3 9 shows th is last s tep, w h i l e F igure 4 0 i l lust rates h o w o t h e r a r rangements o f t h e f u n c t i o n a l surfaces give rise t o o t h e r f o r m design poss ib i l i t ies .

F u n c t i o n a l surfaces are t he basis o f t h e f o r m design o f any p r o d u c t . I t is t he re fo re app rop r i a te t o discuss in m o r e deta i l w h a t , in f ac t , f u n c t i o n a l surfaces are. In a p r o d u c t cons is t ing o f m o r e t h a n one e lemen t the re are t w o t ypes o f f u n c t i o n a l surfaces -ex te rna l and in te rna l . Ex te rna l surfaces have an act ive f u n c t i o n in re l a t i on t o t h e su r round ings , such as a hand le , a s u p p o r t i n g su'-face, etc . T h e internaJ surfaces have an act ive f u n c t i o n in r e l a t i on t o o t h e r e lements o f t h e p r o d u c t .

Th is can be i l l us t ra ted by imag in ing a p r o d u c t as a sys tem cons is t ing o f a n u m b e r o f e lements w i t h ce r ta in re la t ionsh ips t o each o the r . T h e vice in F igure 4 1 m a y t hus be descr ibed as a sys tem s h o w n

4 9

Figure 40 Different cfioices of functional surfaces give rise to different design possibilities

Figure 41 A vice. The starting point for Figures 42 to 44


in F igure 4 2 , where the e lements are represented by b locks and the re la t ionsh ip be tween t h e m and the sur round ings by l ines.

If we consider a par t i cu la r e lement o f t he vice e.g. the s l id ing j aw , w e can see t h a t t he re la t ions correspond exac t l y t o the above m e n t i o n e d f u n c t i o n a l surfaces. The s l id ing jaw has an externa l sur face, cons is t ing o f the surface w h i c h presses on the subject as we l l as o f the t o p ho r i zon ta l sur face. The in terna l surfaces consist o f the hole f o r the sp ind le and the t w o holes f o r the rods. The f u n c t i o n a l surfaces are i l lus t ra ted in Figure 4 3 .

As s h o w n in F igure 4 4 , a spec i f ic a r rangement o f f u n c t i o n a l surfaces can be the basis f o r m a n y f o r m designs, and o t h e r ar rangements can give o the r series o f f o r m designs. In t h e chap te r o n t he f o r m va r i a t i on m e t h o d w e descr ibed t h e w a y in w h i c h t he f o r m design w o r k can be t ack led o n t h e basis o f f u n c t i o n a l surfaces. In the f o l l o w i n g paragraphs i t w i l l be apparen t h o w a great deal o f e f f o r t is needed t o d e t e r m i n e w h i c h f u n c t i o n a l surfaces are t o be used in o rde r t h a t a f i r m and b road basis f o r t he design w o r k is achieved.

LIMIT OF THE SYSTEM

1 SPIKJDLE

OBJECT

FÍJAME WITH FIXED JAW

HANDLE

I .

Figure 42 A vice. Relationship of elements

Figure 43 A vice. The functional surfaces of the sliding jaw

51

Figure 44 Suggested form designs for tfie sliding jaw, based on two different groups of the functional surfaces


Tfie metfiod of variation of thie functional surfaces

A spec i f i ca t ion o f the parameters t h a t de te rm ine the f u n c t i o n a l surfaces o f an e lemen t m a y f o r m the basis o f va r ia t i on me thods f o r generat ing ideas. By systema t i c va r ia t ion o f t he parameters i t becomes possible t o l ist a n u m b e r o f ar rangements o f f u n c t i o n a l surfaces f o r a given e lement . The relevant parameters t h a t can be var ied are: n u m b e r , a r rangement , f o r m

g e o m e t r y and d i m e n s i o n . Figures 4 5 and 4 6 show a n u m b e r o f examples o f p r o d u c t s , where the func t i ona l surfaces are emphasised. T h e p roduc t s are presented in pairs in o rde r t h a t t he f o u r va r ia t i on parameters m a y be observed, p a r t l y f o r the in te rna l and p a r t l y f o r t he ex te rna l f u n c t i o n a l surfaces. As these are na tu ra l l y a par t o f t he f ina l f o r m we shall meet t he f o u r va r ia t ion parameters again in connect i o n w i t h the later sec t ion on the f o r m va r i a t i on m e t h o d .

NUMBER ARRANGEMENT

FORM GEOMETRY DIMENSIONS

Figure 45 Examples of variation of internal functional surfaces based on tfie four variation parameters. Tfie examples sfiown are — a hinge, overhead projector, a socket for a camera lens and a socket for an electric light bulb

53

N U M B E R ARRANGEMENT

FORM GEOMETRY D I M E N S I O N S

Figure 46 Examples of variation of external functional surfaces based on the four variation parameters. The examples are - a wheel for a chair, an electric drill, a hotplate andan electric switch

54

FUNCTIONAL SURFACES

Var iat ion p a r a m e t e r s : - N u m b e r - A r r a n g e m e n t - D i m e n s i o n - Form geomet ry

STARTING POINT:

Lid w i t h packing

N U M B E R

ARRANGEMENT

1= =ÍB ¿=

Figure 47 Variation of functional surfaces for a lid with packing - number, arrangement

In t he f o l l o w i n g paragraphs i t w i l l be s h o w n h o w va r ia t i on o f the f u n c t i o n a l surfaces may be app l ied in a par t i cu la r p r o b l e m . Th is is t o design an area o f pack ing r o u n d a l i d , cover , c o r k o r s imi la r ob jec t . The p r o b l e m is i l l us t ra ted in F igure 4 7 ( inse t ) . A n e x a m i n a t i o n o f t he p r o b l e m o n t he basis o f va ry i ng the f o u r va r ia t i on parameters m a y , f o r instance, give the suggestions s h o w n in Figures 4 7 and 4 8 . These mus t n o t be regarded as f ina l suggestions, b u t o n l y as categories o f so lu t ions , as each o f the suggestions s h o w n mus t be f u r t h e r e labora ted at the deta i l design stage.

Methods used in form design 5 5

DIMENSION

FORM GEOMETRY

5 z ^ ^

Figure 48 Variation of functional surfaces for a lid witfi packing — dimension, form geometry

MINIMUM SURFACE MAXIMUM SURFACE

Figure 49 Minimum and maximum functional surface for a lid witfi packing

T h e va r i a t i on parameters m a y genera l ly be f ree ly var ied inside the l im i t s where t h e f u n c t i o n a l surfaces can f u l f i l l t he i r f u n c t i o n . I f t he f u l l range o f so lu t i ons is t o be t h o r o u g h l y e x a m i n e d i t w i l l be necessary t o evaluate t he l im i t s f o r t he i nd i v i dua l paramaters .

As an overal l check o n t he l im i t s i t m a y be usefu l t o exam ine the f u n c t i o n a l surfaces w i t h t h e greatest e x t e n t and those w i t h t h e smal lest e x t e n t . Such surfaces m a y be su i tab l y cal led m a x i m u m and m i n i m u m surfaces, see F igure 4 9 .


T h e conveyo r ' s f u n c t i o n a l surfaces mus t f o r m a s u p p o r t so t h a t t he tubes c a n n o t fa l l over. A m a x i m u m sur face is easy t o de f i ne , name ly a ho le w i t h a r o u n d b o t t o m , w h i c h can c o m p l e t e l y s u r r o u n d t he test t u b e . A m i n i m u m surface is t heo re t i ca l l y th ree po in ts s u p p o r t i n g t h e tab le , b u t as t he t u b e mus t n o t be able t o fa l l over by acc iden t , i t mus t be supp o r t e d o n at least f ive o r six po in ts . T h e design o f t he c o n v e y o r is s h o w n in F igure 5 1 . I t is c o n s t r u c t e d so t h a t t he tubes are s u p p o r t e d a t f i ve po in t s by the c o n v e y o r and at a s i x t h one , b e l o w , by a f i x e d tab le t o p over w h i c h t he tubes sl ide. M i n i m u m surfaces f o r t he c o n v e y o r have been chosen in th is case because the c o n v e y o r , as we l l as t h e test tubes , goes t h r o u g h b o t h the heater and t he c o o l i n g zone and so the heat capac i t y o f the c o n v e y o r needs t o be k e p t t o a m i n i m u m .

T h e load ing system is a funne l -shaped magazine w h i c h can take t h i r t y test tubes. T h e tubes are passed a long by be ing grasped one at a t i m e by a d r u m , w h e r e u p o n t h e y are swung d o w n i n t o the c i rcu la r

Figure 50 Machine for filling test tubes. This machine carries out automatic sterilisation, filling with the correct dose, corking and labelling of test tubes (Inst, for Product Development,

The Technical University of Denmark)

I t is, o f course, a personal ma t t e r w h e t h e r one decides t o app l y t he va r i a t i on pr inc ip les sys temat i ca l l y , o r w h e t h e r one s i m p l y uses m a x i m u m and m i n i m u m surfaces supp lemen ted by a f e w possib i l i t ies in be tween . In any case, a know ledge o f t he va r ia t i on o f n u m b e r , a r rangement , f o r m g e o m e t r y and d imens ion is i m p o r t a n t , w h e t h e r i t is app l ied consc ious ly o r is s i m p l y pa r t o f t h e a t t i t u d e w i t h w h i c h one a t tacks a given task. Let us t he re fo re c o n sider some detai ls in a spec i f ic mach ine on the basis o f a m o r e f l ex i b l e a t t i t u d e , wh i l e p r i m a r i l y s t u d y i n g m a x i m u m and m i n i m u m surfaces.

F igure 5 0 shows a mach ine t h a t can car ry o u t a n u m b e r o f processes w i t h test tubes in c o n n e c t i o n w i t h nu t r i en ts f o r tests o n bacter ia . The processes t h a t t he test tubes go t h r o u g h are: s te r i l i sa t ion (by hea t ) , c o o l i n g , f i l l i n g w i t h n u t r i e n t , c los ing w i t h a ster i le w a d o f c o t t o n w o o l and labe l l ing. T h e tubes are loaded m a n u a l l y , t r anspo r ted t h r o u g h the mach ine o n a c o n t i n u o u s c i rcu la r c o n v e y o r and t a k e n o u t by h a n d .

57

FROM ABOVE SIDE V I E W

Toothed w h e e l

Guide r a i l

Test t u b e

Figure 51 The functional surfaces in the circular conveyor in the test tube machine are designed as minimum surfaces

5 8

MAXIMUM SURFACES

FUNCTION

/////////////////λ

MINIMUM SURFACES

Figure 52 L oading system for the test tube filling machine. The actual design as well as other functional surfaces are shown

59

FUNCTION

MAXIMUM SURFACES M I N I M U M SURFACES

Figure 53 Unloading system of tfje test tube filling machine


conveyo r as s h o w n in F igure 52 . I f the load ing system is cons t ruc ted using m a x i m u m surfaces the tubes mus t be suppo r t ed and gu ided as m u c h as possible. The resul t can be seen at the b o t t o m le f t in F igure 52 . T o design the f u n c t i o n a l surfaces as m i n i m u m ones, the desired f u n c t i o n may be achieved as long as the tubes are cons tan t l y suppo r ted at f o u r po in t s , see Figure 52 , b o t t o m r ight . In the mach ine , the load ing system is designed using m a x i m u m surfaces t o prevent damage t o the tubes and t o p revent t he ope ra to r ge t t ing his f ingers t r apped .

When , a f te r the cyc le is c o m p l e t e d , the test tubes leave the c i rcu la r c o n v e y o r t h e y are grasped by a d r u m w h i c h passes t h e m up i n t o a magazine, where the opera to r can remove t h e m . T h e o p e r a t i o n o f t he un load ing d r u m is i l lus t ra ted in Figure 53 , t o p . The d r u m rotates o n a s lop ing axis, so t h a t the test tubes are moved in a h y p e r b o l o i d plane. When the tubes have c o m p l e t e d a ha l f c i r c u i t t h e y are f o r ced up i n t o the magazine. If m a x i m u m surfaces are used f o r t he d r u m , we get a design l ike the one b o t t o m le f t in Figure 53 . A m i n i m u m surface w i l l be c o m p l e t e l y analogous t o the c i rcu la r conveyo r in Figure 54 , as i t is su f f i c i en t t o have t w o po in ts o f con tac t above and t w o be low as we l l as a p o i n t in the m idd le and one at the b o t t o m . In the mach ine , t he d r u m is designed w i t h f u n c t i o n a l surfaces close t o the max i m u m . Here again, the ma in reason is t o prevent damage t o t he test tubes.

Restrictions on form design

Banned areas: 1. Areas in space w h i c h are s t r uc tu ra l l y con

d i t i o n e d mus t n o t be o b s t r u c t e d , i.e. o the r e lements mus t n o t be hampered ( th is appl ies t o b o t h s ta t i ona ry and movab le e lements ) .

2. Areas in space w h i c h are f u n c t i o n a l l y con d i t i o n e d mus t n o t be o b s t r u c t e d , (e.g. the objects in t he process, rays o f l i gh t and jets o f w a t e r ) .

3. Areas in space w h i c h are ope ra t i ona l l y con d i t i o n e d mus t n o t be obs t r uc ted (e.g. r o o m f o r a hand , r o o m f o r an ope ra to r , e t c ) .

On the basis o f these banned areas one can n o w d r a w up a n u m b e r o f f o r m design suggestions t ha t r o u g h l y show where in space the connec t i ons mus t be pu t . The nex t step is t o dec ide o n the f o r m geom e t r y and t he d imens ions — f i rs t as rough sketches and , the rea f te r , in deta i l d rawings , judged on f o r instance techno log ica l o r aesthet ic c r i te r ia (see also Chapte r 3 ) .

I t is i m p o r t a n t t o no te f r o m the preced ing c o m ments t h a t the f o r m design o f an e lemen t con ta ins b o t h a qua l i ta t i ve and a quan t i t a t i ve par t . A n y dec is ion on d imens ions is i r re levant un t i l i t has been dec ided h o w the mater ia l w i l l be ar ranged, e.g. w h e t h e r a f u n c t i o n a l surface w i l l be suppo r t ed at one p o i n t o r at several. T h e n u m b e r o f e lements and the relat ive a r rangement o f t he connec t i ons be long t o the qua l i ta t i ve par t o f the f o r m design, wh i l e geom e t r y and d i m e n s i o n be long t o the quan t i t a t i ve one. The f o l l o w i n g sect ion exp la ins h o w the va r ia t i on o f parameters can be app l ied .

Let us imagine t h a t we have a proposal f o r the f o r m design o f the f u n c t i o n a l surfaces o f an e lement . H o w then d o we move o n f r o m there? As has a l ready been m e n t i o n e d , the f u n c t i o n a l surfaces mus t be connec ted together . The p r o b l e m is n o w t o arrange the connec t ions so t h a t the e lement can f u n c t i o n in use. T h e role o f t he e lement w h e n in use mus t t he re fo re be assessed and taken i n t o cons ide ra t i on .

The c o n d i t i o n s t h a t may have t o be taken accoun t o f in the f o r m design o f an e lement can be f o r m u l a t e d as f o l l o w s :

The form variation method

The va r ia t i on parameters : n u m b e r , a r rangement f o r m geome t r y and d i m e n s i o n , are general f o r m parameters, and we have a l ready s h o w n h o w these may be used in the search f o r possible f u n c t i o n a l surfaces. The i n te rac t i on o f the f o u r parameters w i t h the f o r m o f the mater ia l t ha t connects the f u n c t i o n a l surfaces is i l l us t ra ted in Figures 54 and 55 .


N u m b e r

Figure 54 The variation parameters of number and arrangement can be used in connection with arranging the materia/ area to connect the functional surfaces. The examples show two sprinkler valves and two motor lawn mowers

62

D i m e n s i o n

Figure 55 The variation parameters of form geometry and dimension can be used to specify the form when the materia/ area (see Figure 54) has been chosen. The examp/es show two nutcrac/cers and two c/amps

Methods used in form design 6 3

T a k i n g a t y p i c a l exannple - t h e f r a m e in a h y drau l ic press - w e n o w observe h o w t h e v a r i a t i o n parameters can be used in designing an e lement . T h e f r a m e o f the press con ta ins t w o f u n c t i o n a l surfaces, namely the fasten ing areas f o r respect ively the h y d r a u l i c c y l i n d e r and t h e pressure p late , see F igure 56 . When designing the f r a m e there are three banned areas:

1. There must be r o o m f o r the p i s t o n in all its pos i t ions ;

2. There m u s t be r o o m f o r an o b j e c t o f a c losely d e f i n e d m a x i m u m size;

3. There m u s t be r o o m f o r t h e o b j e c t t o be p u t i n t o and t a k e n o u t o f the press.

In o t h e r w o r d s t h e f r a m e m u s t be designed so t h a t t h e t w o f u n c t i o n surfaces are c o n n e c t e d i n a w a y w h i c h takes a c c o u n t o f t h e banned areas, and w h i c h a l lows i t t o f u l f i l l its f u n c t i o n — t o t r a n s m i t t h e necessary forces .

F igure 57 shows h o w t h e v a r i a t i o n o f n u m b e r and a r rangement o f e lements m a y be used t o e x a m i n e w h e r e t h e mater ia l can l ie . A f t e r t h a t , t h e v a r i a t i o n o f f o r m g e o m e t r y and d i m e n s i o n m a k e i t possible t o deta i l a n u m b e r o f r o u g h design suggestions o r f o r m c o n c e p t s .

F o r c o m p a r i s o n . F igure 5 8 shows t h e design o f a n u m b e r o f e x i s t i n g presses.

FUNCTIONAL SURFACE

A f f i x i n g of hydraul ic c y l i n d e r

FUNCTIONAL SURFACE

A f f i x i n g of p ressure p l a t e

B A N N E D AREA

Room for the object to be pressed, and room for the p i s t o n

BANNED A R E A

Room for the ob ject and f o r hands and a r m s whi le loading and u n l o a d i n g

Figure 56 Functional surfaces and banned areas in connection with the form design of a frame for a hydraulic press

6 4

FORM CONCEPTS

V a r i a t i o n p a r a m e t e r s : N u m b e r - A r r a n g e m e n t - F o r m g e o m e t r y - D i m e n s i o n

N U M B E R

ARRANGEMENT

FORM GEOMETRY

DIMENSION

On o;

Figure 57 Form concepts for a frame for a hydraulic press

6 5

Figure 58 Hydraulic press. See also Figure 57


A m o r e de ta i led use o f t he va r i a t i on parameters is possible t h r o u g h a closer i nd i ca t i on o f t he mater ia l areas be tween the f u n c t i o n surfaces. Th is is i l l us t ra ted in t he f o l l o w i n g examp le .

F igure 59 shows the f u n c t i o n a l surfaces in a f o r k j o i n t w i t h a single bear ing at one end and d o u b l e bearings at t h e o the r . In va ry i ng t h e mater ia l area i t is app rop r i a te t o use th ree sorts o f s y m b o l s ; a l ine f o r some th ing t h a t is a p p r o x i m a t e l y a rod (s t ra ight o r cu r ved ) , a ha tched plane f o r s o m e t h i n g f l a t , a n d f i n a l l y a ha tched area f o r s o m e t h i n g s o l i d , i.e. mater ia l in th ree d imens ions . Va^-iat ion o f f o r m geome t r y and d imens ion can resul t in a series o f

f o r m proposals as s h o w n In F igure 6 0 . N o t e t h a t i t is usefu l t o w o r k at t w o levels o f abs t rac t i on , n a m e l y , w i t h a series o f so lu t i ons w h e r e n u m b e r and a r rangement are var ied (F igure 59 ) and one w h e r e f o r m g e o m e t r y a n d d i m e n s i o n are var ied (F igu re 6 0 ) . N o t e also t h e cons iderab le d i f f e rence in i l l u s t r a t i on t e c h n i q u e .

T h e f o r m proposals m u s t n o w be f u r t h e r de ta i l ed , and i t becomes necessary t o t ake i n t o cons ide ra t i on t h e f o r m fac to rs (see p. 9 8 ) t h a t ac tua l l y ex is t . In t h e examp le o f t h e f o r k j o i n t , t he m a n u f a c t u r i n g process becomes a decisive f a c t o r f o r t h e cho ice o f design, c o m p a r e Figures 6 0 a n d 9 8 .

FORM CONCEPTS

Var ia t ion parameters : Number^ a r r a n g e m e n t

FUNCTIONAL SURFACES

Φ:.

RODS

P L A N E S

SOLID

COMBINATIONS

Figure 59 Form concepts for a for/< Joint at the most abstract level, where the number and arrangement of the material areas are examined

6 7

FORM CONCEPTS

RODS

P L A N E S

SOLID

i 1 1 , * 1

COMBINATIONS

I — •

Figure 60 Form concepts for a forl< joint drawn up on the basis of Figure 59 and variation of form geometry and dimension. (See also Figure 98)


Fina l l y t he f o r m var ia t ion m e t h o d w i l l be i l lust ra ted by a s l igh t ly more c o m p l e x examp le , a m ic roscope . We have a l ready s tud ied the q u a n t i f i e d s t ruc tu re f o r a m ic roscope designed on the t rad i t i ona l p r i nc ip le , see Figure 23 .

I f the t ube is made ver t ica l or s l igh t l y s lan t ing the c o n d i t i o n s f o r the design o f t he f rame m a y be i l lus t ra ted as s h o w n in F igure 6 1 . The mos t im p o r t a n t f u n c t i o n a l surfaces o f t he f r a m e are surfaces f o r f i x i n g the t u b e , t he stage, the ad jus t ing k n o b and the m i r r o r as we l l as the s u p p o r t i n g base. The banned areas are the t u b e , the stage, the ad jus t ing k n o b , the m i r r o r and the tab le t o p as we l l as t he rays f r o m the l igh t source t h r o u g h the m i r r o r t o the ob jec t and on t o the t ube . There are also banned areas over the t ube (where the ope ra to r is l ook ing ) and oppos i te the stage and the ad jus t ing k n o b (where t he opera to r ' s hands mus t have r o o m t o w o r k . )

When the above c o n d i t i o n s are f u l f i l l e d the f r ame

mater ia l m a y be arranged f ree ly in space and Figure 6 2 shows a n u m b e r o f suggested f o r m designs d r a w n up by va ry ing the n u m b e r o f e lements and arrangem e n t . A d iv i s ion i n t o rods, planes and so l id shapes has been made, as in the prev ious examp le . N o t e t h a t f o r some o f t h e parameters one can cons ider m a x i m u m and m i n i m u m values. F igure 6 3 shows f o r m concepts ar is ing o u t o f va r i a t i on o f t h e f o r m g e o m e t r y and the d i m e n s i o n .

In F igure 6 2 and 6 3 i t can be seen t h a t va r i a t i on o f n u m b e r and a r rangement can be car r ied o u t qu i t e sys temat i ca l l y , w h i l e i t is unrea l is t i c t o w o r k sys temat i ca l l y w h e n va ry ing f o r m g e o m e t r y and d i m e n s i o n . Here t h e m o s t app rop r i a t e course is t o c o m b i n e the suggestions ar is ing f r o m va ry ing n u m b e r and ar rangement w i t h d i f f e r e n t basic geomet r i c shapes and use th is as a source o f ideas f o r f o r m suggestions. F igure 6 4 shows a series o f ex i s t i ng microscopes.

6 9

Funct iona l s u r f a c e for the f r a m e

Banned areas for the f r a m e

Figure 61 Functional surfaces and banned areas for the frame of a microscope

70

FORM CONCEPTS

Var ia t ion p a r a m e t e r s : Number - A r r a n g e m e n t

RODS

7 ^cy

P L A N E S

-7 SOLID

COMBINATIONS

FUNCTIONAL SURFACES

Tube

- Stage

Support ing base

Figure 62 Form concepts for ttie frame of a microscope

FORM CONCEPTS

V a r i a t i o n p a r a m e t e r s : Form g e o m e t r y , d i m e n s i o n

71

RODS

3̂ P L A N E S

SOLID

COMBINATIONS

4

7 5

J

7 · ¿ 5

Figure 63 Form coricepts for the frame of a microscope

72

Figure 64 Various types of microscope (See also Figures 62 and 63). (Courtesy of Olympus, Carl Zeiss, Carl Zeiss JENA, Leitz, Ealing Beck, Vickers)

73

Figure 64 (continued!


The form division method

I f t he examples in the prev ious sect ion are s tud ied c losely one more parameter can be i d e n t i f i e d . Th i s , t h r o u g h consc ious va r i a t i on , can give rise t o ideas f o r a n u m b e r o f suggestions f o r t he design. I f t he microscopes in F igure 6 4 are c o m p a r e d i t is obv ious t h a t one mic roscope f rame consists o f mo re e lements t h a n ano ther .

Th is cho ice o f d i v i d i ng i n t o more e lements or in tegra t ing i n to a f e w is a cho ice w h i c h is a lways avai lable. The d iv is ion need n o t lead t o mo re phys ica l l y separate e lements , as i t m a y be caused by a visual d iv is ion o f a phys ica l l y w h o l e e lement . F igure 6 5 i l lustrates t h e po in ts o f v iew f r o m w h i c h a p r o d u c t o r a mach ine m a y be d i v ided i n t o e lements . F i r s t l y ,

t he d iv i s ion m a y be done f o r reasons o f f u n c t i o n , second ly f o r phys ica l reasons, i.e. w h e t h e r the elements can be separated f r o m each o t h e r , and t h i r d l y f o r visual reasons.

A de l ibera te va r i a t i on o f t h e n u m b e r o f e lements m a y be su i tab ly ca l led t he f o r m d iv i s ion m e t h o d , bear ing in m ind , t h a t i t m a y be a ques t i on o f a d i v i s ion i n t o m o r e e lements as we l l as an i n teg ra t i on i n t o a f e w — poss ib ly i n t o a single w h o l e one .

In the examples on t he f o l l o w i n g pages the phys ica l and t he visual d iv is ions are cons ide red . I nc iden ta l l y i t is n o t s ta ted w h e t h e r t he e lements are phys ica l l y separable o r n o t , as e i ther t y p e m a y be possible w h e n a speci f ic design is cons ide red .

PRODUCT

ELEMENTS F u n c t i o n a l d i v i s i o n

ELEMENTS V i s u a l d i v i s i o n

ELEMENTS Phys ica l d i v i s i o n

Figure 65 Different points of view according to which a product may be divided into elements


Figure 6 6 shows a pawl w i t h f o u r f u n c t i o n a l surfaces, — the area o f the b reak ing f u n c t i o n , t he area o f t he bear ing, t he area o f f inger pressure and t he area o f pressure f o r a mechanica l sys tem, w h i c h mus t be moved s imu l taneous ly w i t h the paw l be ing released. I f i t is assumed t h a t t he pawl mus t be f o r m designed a p p r o x i m a t e l y as s h o w n in the i l l u s t r a t i o n , t h a t is t o say t h a t t h e mater ia l areas are laid d o w n , the f o r m d iv is ion m e t h o d m a y give rise t o t he f o r m

design proposals s h o w n . N o t e t h a t t he n u m b e r o f par t e lements goes f r o m 1 ( comp le te i n teg ra t i on ) t o 5. I t m u s t be emphasised t h a t t he f o r m d iv i s ion has no f u n c t i o n a l i m p o r t a n c e , b u t i t m a y be very imp o r t a n t f o r t h e m a n u f a c t u r i n g process and so f o r the economics .

In F igure 6 6 paw l 4 w i l l be the cheapest one i f o n l y one is t o be made , whereas paw l 1 m a y be cheapest in mass p r o d u c t i o n .

FORM CONCEPTS

Var iat ion parameter : Form d iv is ion

FUNCTIONAL SURFACES APPROXIMATE DESIGN

6

Í 2 ^ L=röHi

Figure 66 Form concepts for a pawl based on variation of the form division


We w i l l n o w demons t ra te the a p p l i c a t i o n o f t he f o r m d iv i s ion m e t h o d o n an e lemen t by one more examp le . The bear ing in F igure 67 con ta ins t w o areas o f bear ing and a s u p p o r t i n g sur face, and the a p p r o x i m a t e f o r m design is s h o w n . T h e rest o f the

f igu re con ta ins a n u m b e r o f ideas t o w h i c h t he f o r m d iv i s ion m e t h o d gives rise. Here aga in , an essential f a c t o r in t he cho ice o f f o r m design w i l l be the m a n u f a c t u r i n g process.

FORM CONCEPTS

Var iat ion p a r a m e t e r : Form d iv is ion

APPROXIMATE DESIGN

Figure 67 Form concepts for a double bearing


In t he i n t r o d u c t i o n t o th is chap te r , i t was ment i o n e d t h a t t he me thods in ques t i on m a y be used in designing e i ther e lements or c o m p l e t e p roduc t s . Th is also appl ies t o the f o r m d iv i s ion m e t h o d .

As an examp le let us s t u d y the tea maker in F igure 3 5 . I t is assumed t h a t w e w i l l e xam ine t he f o r m s t h a t are possible i f b o x shaped conta iners are

chosen , p laced side by side as s h o w n in t he inset in F igure 6 8 . ( In t h e same w a y o the r shapes o f con ta ine r m a y be e x a m i n e d ) . In the i l l us t ra t i on a n u m b e r o f possib i l i t ies are i l l us t ra ted f o r d i v i s ion or i n teg ra t i on o f t he th ree e lements c o m p r i s i n g bo i le r , b r e w i n g vessel and p l i n t h .

FORM CONCEPTS

Var ia t ion p a r a m e t e r : F o r m division

ARRANGEMENT OF ELEMENTS

Κ

APPROXIMATE DESIGN

Figure 68 Form concepts for a teamal<er. (See also Figure 35)


A m o r e f l ex i b l e a p p l i c a t i o n o f t he f o r m d iv i s ion m e t h o d is s h o w n in F igure 6 9 , where a ca lcu la to r is be ing cons idered . T h e possib i l i t ies f o r va r i a t i on are numerous , as any plane whatsoever can be in tegra ted i n t o or separated f r o m the o the r planes. T h e c r i te r ia

f o r dec id ing t h e cho ice o f f o r m design w i l l be t h e m a n u f a c t u r i n g process, t he appearance, c lean ing , etc . (see also Chap te r 3 ' F o r m f a c t o r s ' ) . A n u m b e r o f ca lcu la to rs are s h o w n , f o r c o m p a r i s o n , in Figures 70 and 7 1 .

APPROXIMATE DESIGN

FORM CONCEPTS

Var ia t ion p a r a m e t e r : Form d i v i s i o n

Figure 69 Form concepts for a calculator

79

Figure 70 Types of calculator. (See also Figures 69 and 71). (Courtesy of Olympia, .Facit and Cannon)

8 0

Figure 71 Types of calculator. (See also Figures 69 and 70). (Courtesy of Olympia, Diefil and Facit)


Figure 72 Pneumatic motors with a different form division, (A tias Copeo L td.)

I f i t is car r ied o u t w i t h i m a g i n a t i o n , va r i a t i on o f d i v i s ion f o r t he i nd i v idua l p roduc t s m a y be n o t e d , t he f o r m d iv i s ion m a y f o r a given p r o d u c t p roduce (see Figures 7 2 t o 7 6 ) . I t is obv ious f r o m the ex-m a n y d i f f e r e n t and e x c i t i n g designs. I t w i l l t he re fo re ampies t h a t a change in the f o r m d iv i s ion m a y be useful t o show a n u m b e r o f examples o f p roduc t s occas iona l ly cause a radical a l t e ra t i on o f a we l l -presented in pairs, so t h a t t he d i f f e rence in f o r m k n o w n p r o d u c t .

82

Figure 73 Motor bicycles with different form division

Figure 74 Watering cans with different form division

83

Figure 75 Petrol pumps with different form division. (Danish Industrial Syndicate Ltd.)

Figure 76 Hole punches with different form division


A coherent example: a pulley

I t is usual ly app rop r ia te t o vary t he f ive f o r m variat i o n parameters in t he f o l l o w i n g o rde r : n u m b e r and a r rangement ; f o r m geome t r y and d i m e n s i o n ; f o r m d i v i s ion . I t is, however , n o t cer ta in t h a t in a given s i tua t ion all f ive parameters can be used. Fo r instance, the ar rangement o f a mater ia l area may be ru led by so m a n y c o n d i t i o n s t h a t there is o n l y one place f o r i t . A l t e r n a t i v e l y , f o r m geomet r y may be dec ided in advance. B u t th is takes us on t o the c r i te r ia and cond i t i ons t ha t app ly in a speci f ic s i t u a t i o n , w h i c h is t he subject o f Chapter 3. A n example o f t he general s i t ua t i on , where all f ive va r ia t i on parameters can be used, is shown be low .

The ob jec t t o be examined is a pu l l ey , e.g. a con veyor bel t . The pu l ley has t w o f u n c t i o n a l surfaces, the ro l l i ng surface and the bearings.

V a r i a t i o n o f f u n c t i o n a l surfaces has been car r ied o u t in Figure 77 , where f o u r va r ia t i on parameters as wel l as m a x i m u m and m i n i m u m surfaces are i l lust r a ted . T w o groupings o f f u n c t i o n a l surfaces have been chosen f o r f u r t h e r e x a m i n a t i o n , and in F igure

78 possible mater ia l areas are s h o w n based on a va r i a t i on o f numbers and relat ive a r rangement . A d iv i s ion o f t he mater ia l areas i n t o the f o r m o f rods, planes or sol ids is use fu l . F igure 79 shows h o w , by va ry ing the f o r m geome t r y and the d i m e n s i o n , a n u m b e r o f m o r e speci f ic f o r m design ideas can be g iven. Possible f o r m div is ions f o r a f e w o f these ideas are s h o w n in F igure 80 .

T h e f i na l dec is ion o n the f o r m depends largely o n the cho ice o f mater ia l and m a n u f a c t u r i n g process (see sect ion 3.4) and poss ib ly also on an eva lua t ion o f the appearance. By using sketches, models and scale drawings one can decide on all the deta i ls , w h i c h are then d o c u m e n t e d in a set o f w o r k i n g d rawings w i t h the a c c o m p a n y i n g assembly d r a w i n g . N a t u r a l l y th is p lan , w h i c h cor responds t o Figures 77 t o 8 0 , is very schemat ic . Th is is in o rde r t o underl ine the steps one mus t basical ly take in des ign ing. A more re laxed a t t i t u d e t o th is w i l l p r o b a b l y be m o r e real ist ic, as can also be seen f r o m the case h i s to ry in Chapter 5.

8 5

F U N C T I O N A L SURFACES

V a r i a t i o n p a r a n n e t e r s : N u m b e r - A r r a n g e m e n t - F o r m g e o m e t r y - D i m e n s i o n

STARTING POINT: P u l l e y and b e a r i n g s

NUMBER

ARRANGEMENT

FORM GEOMETRY

D I M E N S I O N

M A X I M U M SURFACES M I N I M U M SURFACES

P o s s i b l y

Figure 77 Variation of functional surfaces for a pulley on a conveyor belt

86

FORM CONCEPTS

Var ia t ion p a r a n n e t e r s : Nunnber, a r r a n g e m e n t

RODS

SHEETS

SOLID

RODS

SHEETS

SOLID

FUNCTIONAL SURFACES 1

FUNCTIONAL SURFACES 2

Figure 78 Form concepts for a pulley at the most abstract level, where the number and arrangement of the material areas are examined

87

FORM CONCEPTS

V a r i a t i o n p a r a m e t e r s : F o r m g e o m e t r y , d i m e n s i o n

1 7ZZZ

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F/^íyre 7P F o r m concepts for a pulley arrived at by varying the form geometry and dimension of selected solutions from Figure 78

8 8

FORM CONCEPTS

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I Figure 80 Form concepts for a pulley. Two of tfie suggested solutions in Figure 79 have been detailed to a certain level by varying the form division. For the final detailed design the design engineer must first decide on the manufacturing

processes to be used. (See also Figure 95)

V a r i a t i o n p a r a m e t e r : F o r m d i v i s i o n

The application of form synthesis methods

Having s tud ied t he basis o f f o r m synthesis m e t h o d s , i t is n o w possible t o l o o k at t he i r app l i ca t ions . T h e me thods f o r va ry ing t he s t ruc tu re , f u n c t i o n a l surfaces and f o r m may all be app l ied in very d i f f e r e n t s i tua t ions , f o r instance, (as a l ready m e n t i o n e d ) in dec id ing on b o t h the t o ta l f o r m and t he deta i ls o f p r o d u c t . T h e me thods also m a y be used f o r c o m p o u n d p roduc ts (machines, apparatus , e tc) and f o r p roduc ts cons is t ing o f o n l y one e lement ( b o t t l e openers, f i t t i ngs , jugs, e t c ) , excep t t h a t in th is case the s t ruc tu re va r ia t ion m e t h o d is exc l uded .

O f course, in demons t ra t i ng these me thods i t has n o t been the i n t e n t i o n t o argue t h a t t h e y m u s t all be app l ied t o all t he e lements in a p r o d u c t . Th is is unreal is t ic . O n t h e o the r h a n d , t he m e t h o d s can give rise t o a consc ious systemat ic approach t o specia l ly i m p o r t a n t e lements , so t ha t these p r o b a b l y are designed as we l l as possible. The me thods m a y also be used t o great advantage in a s i t ua t i on where one has g o t s tuck in designing a given e lement .

In the c o l l a b o r a t i o n be tween the design engineer and t he process t echn i c i an , t he idea o f f u n c t i o n a l surfaces can be especial ly va luable. I f , f o r instance, a f o r m deta i l is discussed because the f o r m and t h e m a n u f a c t u r i n g process m i g h t have been be t te r m a t c h e d , i t is easier t o a l ter t he f o r m o f t he c o n nec t ing mater ia l t h a n t h a t o f the f u n c t i o n a l surfaces, because these are ad justed t o co r respond ing surfaces in o the r e lements .

A p a r t f r o m the above -men t i oned occasions f o r using f o r m va r ia t i on me thods , t he la t ter can also

l\/lethods used in form design 89

Making models

Whatever the p r o d u c t , t he f o r m design w o r k can be car r ied o u t w i t h t he he lp o f d i f f e r e n t k inds o f mode ls . Fo r a design engineer t he m o s t i m p o r t a n t k i n d o f mode ls are graphica l ones, i.e. sketches and drawings. We have, t h e r e f o r e , so far exc lus ive ly used these w h e n descr ib ing t h e f o r m va r i a t i on m e t h o d s . O the r categor ies o f mode ls , howeve r , are also re levant f o r t he design engineer.

F o r m mode ls can be used in m a n y d i f f e r e n t s i tua t ions in a design p ro jec t .

The decisive factor is: w h a t the mode l w i l l be used f o r .

On the basis of this can be decided: h o w de ta i led t h e mode l mus t be, and o f w h a t mater ia l i t mus t be made.

A consc ious dec is ion o n the degree o f de ta i l and the cho ice o f mater ia l is necessary f o r an o p t i m u m m o d e l , i.e. one w h i c h as cheap ly as poss ib ly expresses w h a t is needed. The use t o w h i c h the m o d e l is p u t t o a f fects the cho ice o f degree o f deta i l and o f m o d e l l i n g mater ia l and th is is i l l us t ra ted in t h e examples o n pages 9 0 - 9 2 .

make t he basis f o r an a t t i t u d e o f m i n d w h i c h results in a sharpened awareness o f w h a t one is w o r k i n g w i t h in a real s i t ua t i on ( s t ruc tu re , f u n c t i o n a l surfaces, f o r m ) , and w h i c h leads t o a greater w e a l t h o f ideas t h r o u g h a m o r e o r less subconsc ious f o r m va r i a t i on .


Figure 81 Model of a diesel engine mounting constructed in foam rubber, Witt) rough models such as these it is possible to obtain a first impression of the correlation

between rigidity and the different stiffeners

Figure 81 shows some mode ls t h a t have been used f o r an eva lua t ion o f the relat ive r i g i d i t y o f d i f f e r e n t l y designed m o u n t i n g s f o r diesel engines. The models are used in t he ear ly design stages w h e n i t has t o be dec ided where in space the mater ia l mus t be concen t ra ted ( in the f o r m o f r ibs) . Re la t ive ly rough models o f f o a m rubbers are the re fo re su i tab le , pa r t l y because t h e y are q u i c k and cheap t o make , and pa r t l y because the degree o f r i g i d i t y can be assessed by s l ight f inger pressure, as the bu lg ing can be seen.

F igure 8 2 shows a m o d e l o f t he tea maker discussed in Chapter 1. The mode l has o n l y been used t o assess the c o n d i t i o n s d u r i n g use and i t is, t he re fo re , very rough l y cons t ruc ted in p last ic f o a m . T h e mode l was n o t t o be used f o r j udg ing the appearance, as i t w o u l d t h e n have had t o be m o r e deta i led and so become t o o expensive. T h e appearance was judged o n the b a c k g r o u n d o f ano the r t y p e o f m o d e l , name ly , th ree-d imens iona l sketches.

Figure 82 Model of a teamaker in plastic foam. This model can be used to evaluate the conditions during use


Figure 83 Model of test tube filling machine (see Figure 50). The materials used are plastic foam, cardboard and wood. The model is used for evaluation of conditions during use. (Courtesy of The

Institute for Product Development, Technical University of Denmark)

Figure 84 Model of a machine for the automatic labelling of filled test tubes. It is made of plastic foam and cardboard and used for an evaluation of conditions during use as well as appearance. (This was a student project from the Laboratory of Engineering Design, University

of Denmark)

Figures 83 and 8 4 s h o w t w o mode ls t h a t have test t u b e f i l l i n g mach ine (F igure 50 ) p rev ious ly

b o t h been used t o assess o p e r a t i o n , space and m e n t i o n e d , and F igure 8 4 shows a m o d e l o f a

appearance. B o t h are made o f p last ic f o a m , card- mach ine f o r t he a u t o m a t i c labe l l ing o f f i l l ed test

board and w o o d . F igure 8 3 shows a m o d e l o f t he tubes .


Figure 85 Mode/ of a pay te/epfione made in clay. It is used to evaluate tfie basic shape of the telephone. (See also Figure 86). (The model was made by Henning Andreasen for GNT

Automatic Ltd)

Figure 86 Mode/ of pay te/ephone made in p/aster of paris. It is so detai/ed as to be indistinguishable from the finished te/ephone. (This

model was a/so made by Henning Andreasen)

T h e mode l in F igure 8 5 has been used t o evaluate d e m o n s t r a t e t h e i n s t r u m e n t t o p o t e n t i a l cus tomers t he basic f o r m o f a co in -opera ted t e l e p h o n e ; i t is be fo re i t was in p r o d u c t i o n . I t is made o f p laster made o f c lay . F igure 8 6 shows a m o d e l o f t he o f paris and is so de ta i led as t o be ind is t ingu ishab le f in i shed te lephone . T h e la t ter has been used t o f r o m the real t e l ephone .

3 FORM FACTORS

3.1 The origination of form requirements 95

3.2 The interdependence of the basic properties 97

3.3 Design factors 99

3.4 Production factors 102

3.5 Sales and distribution factors 116

3.6 Factors concerning the product in use 118

3.7 Destruction factors 140

3.8 Evaluation of form design suggestions 140

9 3

3. Form Factors

3.1 The origination of f o r m requirements

The great m u l t i p l i c i t y o f f o r m design possib i l i t ies t h a t m a y be d r a w n up in a specf ic s i t ua t i on — e i ther by such m e t h o d s as were descr ibed in t he prev ious chap te r o r s imp l y by i n t u i t i o n - m a y f r i gh ten the unp repared . T h e ques t ion q u i c k l y arises o f h o w t o reject the unsu i tab le so lu t i ons . I t was seen ear l ier h o w the p r o d u c t synthesis m a y be character ised by a c o n t i n u o u s a l t e r n a t i o n between searching f o r and select ing ideas, and i t was m e n t i o n e d t h a t one o u g h t o n l y t o select i f su i tab le c r i te r ia f o r se lec t ion are present.

T h e c r i te r ia used are f o r m u l a t e d by t he designer on the basis o f requ i rements f r o m the ou ts ide w o r l d . As all the stages in t he l i fe o f the p r o d u c t (F igure 4 ) can give rise t o demands and requ i rements in respect o f the p r o d u c t we can get a general idea o f where these o r ig ina te . T h e s i t ua t i on m a y be descr ibed as a f o r ce f i e l d where a n u m b e r o f forces t r y t o pu l l t he p r o d u c t in d i f f e r e n t d i rec t i ons . T h e f ina l p r o d u c t w i l l t hen represent an e q u i l i b r i u m — a c o m p r o m i s e - where t he forces balanced each o the r . F igure 87 i l lust rates these c o n d i t i o n s . O n t he ou ts ide are a n u m b e r o f requ i remen ts , p r o d u c t fac to rs , s t e m m i n g f r o m the l i fe o f the p r o d u c t , w h i c h in f l uence i t

t h r o u g h the c r i te r ia t h a t are f o r m u l a t e d . In the m i d d l e are the f i ve basic p roper t ies - s t r uc tu re , f o r m , ma te r i a l , d imens ion and surface — w h i c h spec i fy t he p r o d u c t . These p roper t i es are spec i f ied in the p r o d u c t synthesis in such a w a y t h a t the c r i t e r ia are f u l f i l l e d as fa r as possible. F r o m the basic p roper t ies are der ived all o t he r p roper t ies o f t he p r o d u c t , pa r t i cu l a r l y t he f u n c t i o n , w h i c h is t he cen t ra l p r o p e r t y in t h e process o f use.

I f we cons ider t he basic p r o p e r t y o f f o r m in pa r t i cu la r , w e f i n d t h a t t he in f luences arise, o n t he one h a n d , f r o m the p r o d u c t fac to rs m e n t i o n e d above, and , o n the o t h e r h a n d , f r o m the o t h e r basic p roper t ies , as these are n o t i ndependan t var iables.

T h e dependence o f t he f o r m on the o t h e r basic p roper t i es w i l l be discussed in t he f o l l o w i n g sec t ion . T h e rema inde r o f t h e chap te r deals w i t h t he dependence o f f o r m on the p r o d u c t f ac to rs , w h i c h in th is c o n n e c t i o n are ca l led f o r m fac to rs . T h e f o l l o w i n g paragraphs are o n l y i n tended t o h i n t at t he in f l uence o f t h e separate f o r m fac to rs in o rde r t o d e m o n s t r a t e the i n t e rp l ay . A m o r e p r o f o u n d s t u d y o f ce r ta in o f t he fac to rs , e.g. ' t echno log i ca l l y c o r r e c t ' des ign, can be f o u n d in o t h e r l i t e ra tu re .

9 5

9 6

1. Des ignen

D E S I G N F A C T O R S

2. C o m p a n y : 3. S o c i e t y : A b i l i t y / k n o w l e d g e A i m s o f the c o m p a n y Laws Imag ina t i on Crea t i v i t y H a b i t A t t i t u d e Personal taste E x p e n d i t u r e o f t i m e

P R O D U C T I O N F A C T O R S

1. Manu fac t . process: Feas ib i l i t y Economics Ope ra to r s i t ua t i on

Assemb ly : Feas ib i l i t y Economics Ope ra to r s i t ua t i on

K n o w - h o w W o r k i n g c o n d i t i o n s Economics Con t rac t s Licences Service p o l i c y P r o d u c t series C o m p a n y ' s i d e n t i t y

No rms /s tanda rds Possible f i nance Resources Patents Reg is t ra t ion o f pa t te rns

Using process: 2. User: 3 E n v i r o n m e n t : I n p u t F i t t i n g and r u n n i n g in I n f l uence o f p r o d u c t O u t p u t N o r m a l ope ra t i ons Na tu re o f f u n c t i o n Occasional opera t ions Feas ib i l i t y o f f u n c t i o n Emergency opera t i ons Q u a l i t y o f f u n c t i o n Facts apar t f r o m d i rec t use

Econom ics P recond i t i ons o f user Sub jec t i ve c o n d i t i o n s

on e n v i r o n m e n t In f l uence o f e n v i r o n m e n t

on p r o d u c t

Figure 87 Survey of the life of the product

3.2 The interdependence o f the basic properties

STmrm FOltM MATERIAL

-blMENSIOSJ

The fac t t h a t t he basic p roper t ies are n o t i n d e p e n d e n t can be seen in prac t ice by t h e imposs ib i l i t y o f dec id ing o n t h e m separate ly . T h e s t ruc tu re c a n n o t be f i n a l l y chosen u n t i l the consequences t o t h e f o r m have been es t ima ted , and t h e f o r m c a n n o t be d e t e r m i n e d u n t i l ma te r i a l , d imens ions and surface

Form factors 97

Figure 88 Two drawing instruments with different structures. This illustrates the dependence of form on structure

Figure 89 Springs made of two different materials - rubber and steel. The different properties of the materials result in very different form designs

have been cons ide red . I t is t h e r e f o r e very i m p o r t a n t t o recognize the i n t e rp l ay be tween t h e basic p roper t ies and t h e f o r m .

T h e in f l uence o f t h e s t ruc tu re o n t h e f o r m is d i r ec t , as a l ready m e n t i o n e d (sect ions 2.1 and 2.2) and i l l us t ra ted in F igure 8 8 . The dependence o f t he f o r m o n t he ma te r i a l , d i m e n s i o n and surface is a l i t t l e mo re d i f f i c u l t t o i d e n t i f y , because it takes place i n d i r e c t l y .

T h e i n t e r a c t i o n o f t h e mater ia l and f o r m occurs in t w o ways . F i r s t l y , t h e f o r m depends o n the prod u c t i o n processes by w h i c h the mater ia l can be shaped, and so t h e f o r m depends i n d i r e c t l y o n t he ma te r ia l . S e c o n d l y , t h e p roper t ies o f t h e mater ia l p lay a ma jo r role in d e t e r m i n i n g the f o r m e.g. t he s t r e n g t h , e las t i c i t y and w e i g h t o f the mater ia l (see F igure 8 9 ) .

9 8 Form factors

Figure 90 Cog-wheels showing the influence of the dimensions (size) on the form

Figure 91 The separate products in a product series are usually so designed that they have the greatest possible number of common form features (Danfos Ltd.)

T h e in f luence o f the d imens ions o n t he f o r m is e.g. t he pr ice o f t he mater ia l and t h e w e i g h t , also i l l us t ra ted in F igure 9 0 . Wha t coun ts here is t he fac t change. T h e in f l uence o f t he sur face o n t h e f o r m t h a t , w i t h the change o f size o f t he ob jec t , t he takes place i n d i r e c t l y t h r o u g h t he cho ice o f p roduc -prac t icab le p r o d u c t i o n processes al ter . The c r i t e r i a , t i o n process.

3.3 Design factors

The designer

T h e designer has a decisive in f l uence o n the f o r m o f t he p r o d u c t , as he is t he one w h o mus t b o t h p roduce the ideas and choose t h e design. T h e designer af fects t h e f o r m p a r t l y t h r o u g h a b i l i t y , know ledge and imag ina t i on — as far as seeking so lu t i ons is c o n cerned. Choice is i n f l uenced by the designer 's personal taste, a t t i t u d e and hab i ts . Even w h e n t h e s t i pu la t i ons f o r t h e f o r m design are b i n d i n g , there is a lways some f r e e d o m f o r the imag ina t i on o f t h e designer t o c o m e i n t o p l ay .

Form factors 99

The company

A m o n g t h e m a n y p r o d u c t fac to rs t h a t s tem f r o m the c o m p a n y t he f o l l o w i n g m a y be m e n t i o n e d — c o m pany ob jec t ives , k n o w - h o w , w o r k i n g c o n d i t i o n s , economics , con t rac t s , l icences, service p o l i c y , e tc . N o n e o f these have a d i rec t i n f l uence o n t he f o r m .

A l l t he same, i t w i l l o f t e n be the case t h a t t he f o r m o f a greater o r lesser p o r t i o n o f t he p r o d u c t s have a c o m m o n character . Th is fac t is mos t c lear ly seen in p r o d u c t series, i.e. g roups o f p roduc t s w i t h t he same o f re la ted f u n c t i o n s . A n examp le is s h o w n in F igure 9 1 .

Figure 92 A group of products with common form features can help to make up the identity of a company (Bang and Olufsen)

100 Form factors

Somet imes a f i r m tr ies consc ious ly t o m a i n t a i n a cer ta in i d e n t i t y . T h e a im o f such a c o m p a n y i d e n t i t y is t o create f a i t h in t he c o m p a n y , as we l l as t o m a r k its p roduc ts as against o the r comparab le p r o d u c t s , so t h a t t he user exper iences the c o m p a n y and its p roduc ts in t he same w a y each t i m e .

Th is — toge the r w i t h t he fac t t h a t t h e user in m a n y cases uses several connec ted or re lated p r o d ucts f r o m the same c o m p a n y — leads t o t he exped iency o f a im ing at c o m m o n features in appearance. Such a 'house s t y l e ' m a y be based o n c o m m o n f o r m t ra i ts as wel l as character is t ic cho ice o f mater ia ls and surfaces.

Ttie society

There are t w o aspects o f t he soc ie ty in w h i c h t he p r o d u c t w i l l be used, t h a t mus t be t a k e n i n t o accoun t in t he f o r m design (and , o f course, also ear ly o n in the c rea t ion o f t he p r o d u c t ) . These are f i r s t l y , c o n s idera t ion o f the members o f the soc ie ty , and second ly , c o n f o r m i n g t o i ts no rms and laws. A m o n g t he members o f soc ie ty t o be cons idered f i r s t is t he user, a fac t w h i c h w i l l be discussed later in th is chapter . There are also all t h e people w h o c o m e i n t o con tac t w i t h the p r o d u c t . These m a y be people w h o have t o l isten t o the i r ne ighbour 's m o t o r l awn m o w e r , t o an aeroplane o r a speedboat , and all those w h o each day have t o l o o k at o t h e r people 's cars, excavators and cranes, buses, t ra ins , e tc .

N o r m s and standards ex is t in areas whe re sa fe ty fac to rs are decis ive, or whe re f r e q u e n t use makes s tandard isa t ion necessary, f o r e x a m p l e : nuts and bo l t s , washers, f ish boxes , ra i lway carr iages, and con ta ine rs .

Pa t te rn reg is t ra t ion is a legal p r o t e c t i o n , w h i c h says t h a t o t h e r people have n o r i gh t t o s i m p l y c o p y an o r i g i na l l y designed p r o d u c t . T h e law o n pa t te rns says a m o n g o t h e r t h i ngs :

A p a t t e r n means in th is law t h e m o d e l f o r t h e appearance o f an ar t i c le o r f o r an o r n a m e n t . T h e person w h o has p r o d u c e d a p r o t o t y p e , o r t o w h o m the person's r i gh t has been t r ans fe r red , m a y in accordance w i t h th is law by reg is t ra t ion acqu i re a m o n o p o l y f o r c o m m e r c i a l e x p l o i t a t i o n o f t h e design. T h e pa t t e rn w i l l o n l y be registered i f its is essent ia l ly d i f f e r e n t f r o m w h a t was k n o w n bef o re t he date o f a p p l i c a t i o n .

In des igning a p r o d u c t , p a t e n t reg is t ra t ion m a y c o m e i n t o t he p i c tu re in t w o ways - p a r t l y as l i m i t a t i o n s o f t h e design poss ib i l i t ies , i f registered p roduc t s o f a s im i la r na tu re ex is t in t he m a r k e t , and p a r t l y as a p r o t e c t i o n f o r one's o w n p r o d u c t . F igure 9 3 shows an examp le o f a registered p r o d u c t .

Patents m a y also p lay a pa r t as c o n d i t i o n s in des ign ing a p r o d u c t , so t h a t ce r ta in f o r m possib i l i t ies mus t be le f t o u t , i f t h e y are descr ibed in an ex i s t i ng pa ten t . N o r m a l l y , patents c o n c e r n pr inc ip les a n d s t ruc tu res .

101

Figure 93 A patented photocopier. The characteristic of this particular photocopier is the fact that the original is put in from above and the copy is produced vertically (Zeuthen and Aagaard Ltd.)

102 Form factors

Figure 9 5 shows d i f f e r e n t de ta i led designs f o r a pu l l ey {see also Figures 77 t o 8 0 ) . F r o m these d iagrams i t can be seen t h a t t he re is a close re la t ion sh ip be tween e lements , t h e m a n u f a c t u r i n g and t h e assembly processes.

F igure 9 6 shows t w o bearings whe re t he hous ing o f one bear ing is made in one piece (cast) a n d , t he second is made o f pressed sheet in t w o parts t h a t are subsequen t l y assembled. F igure 9 7 shows t w o versions o f a f r a m e f o r an e l ec t r i c i t y mete r . Here again one vers ion is made in one piece (pressure d ie cast ) , w h i l e t he o t h e r one is made o f s tamped o u t parts t h a t are assembled by spo t -we ld ing . In b o t h cases the re are d i f fe rences in cho ice o f ma te r i a l , f o r m d i v i s i on , m a n u f a c t u r i n g and assembly processes.

I f we r e t u r n t o the m o d e l o f t he f o r m design stages in F igure 9 4 i t m u s t be app rop r i a te t o give an examp le o f h o w t h e synthes is m a y l o o k in t h e last stages. In F igure 9 8 we have taken as a s ta r t ing p o i n t t he ear l ier m e n t i o n e d f o r k j o i n t (see Figures 59 t o 6 0 ) . T h e f o r m c o n c e p t o n w h i c h t h e de ta i led design proposals are b u i l t is s h o w n t o p le f t , and i t is assumed t h a t t he j o i n t is a p p r o x . 1 0 0 m m long and t h a t t he mater ia l is steel. We f i r s t exam ine b y w h i c h processes o r c o m b i n a t i o n s o f processes t h e f o r k j o i n t can be m a n u f a c t u r e d as one e lement . N e x t , w e

F U N C T I O N A L S U R F A C E S

F O R M C O N C E P T S : Mater ia l areas

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F O R M C O N C E P T S : F o r m geome t r y Ma in d imens ion F o r m d iv is ion -f

cho ice o f mater ia l

Cho ice o f m a n u f a c t u r i n g processes and assembly processes

D E T A I L E D D E S I G N

F O R M D I V I S I O N F O R M I N T E G R A T I O N

Figure 94 Ttie form design stages in a design project The stages are gone through for each element

3.4 Production factors

One o f t he mos t i m p o r t a n t quest ions t o be faced w h e n designing a p r o d u c t is h o w t h e p r o d u c t i o n w i l l be car r ied o u t . P r o d u c t i o n can be d i v i ded i n t o t he m a n u f a c t u r e o f the par ts , the assembly and the tes t ing and c o n t r o l . T h e m a n u f a c t u r i n g and the assembly processes are very c losely l i nked t o t he f o r m o f the parts.

In sec t ion 2.3 on f o r m v a r i a t i o n , t he d i f f e r e n t examples d i d n o t end w i t h deta i led design suggest i ons , b u t w i t h a series o f f o r m concepts . There is a na tura l reason f o r th is , name ly t h a t a p r o d u c t or a par t c a n n o t be designed in deta i l u n t i l one has chosen the mate r ia l , m a n u f a c t u r i n g process and assembly process.

T h e stages in the design o f an e lemen t are s h o w n in Figure 9 4 , s ta r t ing f r o m cons idera t ions o f f unc t i ona l surfaces over t w o f o r m concep t levels t o t he cho ice o f processes and a f ina l design o f detai ls . The l oop r o u n d the cho ice o f processes means t h a t , a t any p o i n t , i t is possible t o sp l i t the e lement i n t o several par t e lements w h i c h are later assembled. Cor respond ing l y , i t is somet imes possible t o in tegrate several e lements i n t o one. The stage o f f o r m d i v i s i o n / f o r m in teg ra t i on mus t thus be t h o u g h t o f as a last level o f ideas, w h i c h m a y be used i f one cann o t easily p roduce and assemble one's e lements .

Form factors 103

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Figure 95 DiffererJt detailed designs for a pulley. (See also Figures 77 to 80)

104 Form factors

Figure 96 Two bearings where the casings are respectively cast and made from pressed sheets assembled with bolts (Courtesy SKF)

Figure 97 Two frames for an electricity meter. One frame is pressure die cast and the other is punched out, bent and spot-welded

suggest f o u r new f o r m concepts by f o r m d i v i s i on , n o t all are equa l l y su i tab le in a spec i f ic s i t u a t i o n , and f i na l l y each o f these is exam ined f o r possib i l i t ies The cho ice depends o n such fac to rs as t h e n u m b e r f o r m a n u f a c t u r i n g t h e e lements and f o r t h e assembly t o be p r o d u c e d , the to le rance requ i red , surface process. requ i rements and m a n y o t h e r fac to rs . These requi re-

A l t o g e t h e r the examp le gives f o u r t e e n prac t ica l ments w i l l be deal t w i t h m o r e t h o r o u g h l y in t h e ways in w h i c h t he j o i n t can be p r o d u c e d . Obv ious l y f o l l o w i n g sec t ion .

Form factors 105

M i l l e d M i l l e d M i l l e d

Cas t /m i l l ed

N E W F O R M C O N C E P T S B Y F O R M D I V I S I O N :

E x t r u d e d / s a w n / m i l l e d

Figure 98 Examples of interplay between form concept, form division and choice of manufacturing and assembly processes. (See also Figures 59 and 60)

106 Form factors

The manufacturing process

A c o n d i t i o n f o r be ing able t o choose an o p t i m u m m a n u f a c t u r i n g process is t h a t t he best possible agreement can be achieved be tween t h e design and the process requ i rements . Th is means t h a t t he o rde r s h o w n in F igure 9 4 — f o r m concep t , cho ice o f m a n u f a c t u r i n g and assembly processes, design o f detai ls — mus t be u n d e r s t o o d , bear ing in m i n d t h a t f i r s t t he f o r m concepts are d r a w n u p , t hen the process possib i l i t ies are e x a m i n e d , and f i n a l l y the f o r m concep t and t he processes are chosen as far as poss ib ly s imu l taneous ly . I t is thus usual ly n o t enough t o ad just t he deta i led f o r m t o the process, i f an o p t i m u m p r o d u c t is t o emerge.

The p r o b l e m o f choos ing the m a n u f a c t u r i n g p ro cess be fo re the design o f the detai ls has been t aken t o o far o f t e n occurs in discussions be tween t he designer and the process t echn i c i an . T h e f o r m e r o f t e n tends t o f o rge t t he m a n u f a c t u r i n g process so t h a t t he la t te r has no poss ib i l i t y o f o p t i m i s i n g his con t r i b u t i o n . The ideal w o u l d be i f t he process techn ic ian c o u l d c o m e i n t o the p i c tu re ear ly so t h a t he c o u l d take par t in assessing the f o r m concepts at t he f i r s t stage. In a possible discussion o f proposals f o r a l te ra t ions based o n t he m a n u f a c t u r i n g process, t he idea o f f u n c t i o n a l surfaces is va luable. A f u n c t i o n a l surface can o n l y be a l tered i f o t h e r a l te ra t ions are made s imu l taneous ly elsewhere in the sys tem, wh i l e an a l te ra t i on o f the areas be tween t he f u n c t i o n a l surfaces can be made w i t h m u c h greater f r e e d o m .

As a rule t he designer mus t have an i n t i m a t e k n o w ledge o f t he m a n u f a c t u r i n g processes avai lable. The fac t t h a t ( in t he bigger f i r m s ) there m a y be process techn ic ians w h o can assist in t he de ta i led design does

n o t excuse the designer f r o m k n o w i n g i n t i m a t e l y t he ex is t i ng processes. T h e designer m u s t k n o w a b o u t t h e f o r m geometr ies t h a t can be created w i t h a given process, i n c l u d i n g the t oo l s and f i x i ngs . He mus t also k n o w w h a t mater ia ls can be used in t h e process and t he to lerances w h i c h can be achieved and the surface f i n i s h . Us ing th is i n f o r m a t i o n as a backg r o u n d t he designer m u s t be able t o design his ob jec t so t h a t i t is cheap t o m a n u f a c t u r e .

H o w in prac t ice is i t possible t o choose t h e best possible f o r m concep t and m a n u f a c t u r i n g process? O b v i o u s l y th i s can o n l y be done f r o m a n u m b e r o f c r i t e r ia w h i c h m a y be d i v ided i n t o t he f o l l o w i n g categor ies: f eas ib i l i t y , economics and ope ra to r s i t u a t i o n .

Tfie manufacturing process: feasibility

T h e fac to rs conce rn ing feas ib i l i t y in c o n n e c t i o n w i t h t he cho ice o f process are as f o l l o w s :

f o r m g e o m e t r y , ma te r i a l , s ize /d imens ions , surface requ i remen ts , to le rance requ i remen ts , f o r m (ava i lab i l i t y ) o f t h e i n p u t mater ia ls . T h e f i r s t th ree fac to rs decide w h e t h e r a g iven

process is at all possible. Each process has its o w n character is t ics and l i m i t a t i o n s , as s h o w n in F igure 9 9 . When i n i t i a l l y cons ider ing var ious processes one shou ld n o t choose those at t he ex t remes , so t h a t t h e size is t heo rec t i ca l l y possible b u t in prac t ice d i f f i c u l t t o achieve.

R ( m m ) = 0.4,0.8, 1.0,1.2

R

m D i m e n s i o n s Dírnrrí) P o s s i b l e 1 - - 1 0 . 0 0 0 0 , 5 - 1 5 0 0 Usual - 1 0 - 1 . 5 0 0 a - 3 6 0

Figure 99 Possibilities concerning form geometry and dimensions that can be realised by turning

Form factors 107

I — • Force a c t i n g d u r i n g m a n u f a c t u r e

St i f fen ing rib

Figure 100 Bearings bracket where the forces acting on it during manufacture have been taken into consideration, so that the tolerances can be maintained

T h e fac to rs o f surface and to le rance requ i remen ts mus t also be i nc luded w h e n choos ing the process. I t is n o t enough t h a t these requ i remen ts can t h e o r e t i ca l ly be me t , b u t t h e y mus t also app l y t o the speci f ic ob jec t . T h e examp le in F igure 100 shows a bear ing b racke t , t he design o f w h i c h is su i ted t o the forces t h a t act o n i t d u r i n g p r o d u c t i o n . T h e o n l y purpose the s t i f f en ing r i b serves, in th is case, is t o res t r ic t t h e f l e x i b i l i t y d u r i n g the p r o d u c t i o n s u f f i c i e n t l y f o r the desired to lerances t o be ach ieved.

T h e last f ac to r m e n t i o n e d in t he l ist is t he f o r m of t he mater ia ls used. I t is necessary t h a t t he requ i red mater ia ls ex is t or can be ob ta i ned in the desired f o r m .

Tfie manufacturing process: economics involved in tfie choice of process

E c o n o m i c fac to rs in c o n n e c t i o n w i t h t h e cho ice o f process are:

t h e n u m b e r o f processes requ i red , mate r ia l s : s u p p l y , p r i ce , q u a n t i t y o r o w n m a n u f a c t u r e ; quan t i t i es t o be p r o d u c e d ; m a c h i n e r y ; i nves tmen t in new m a c h i n e r y ; special t oo l s . A n o b j e c t m a y be p r o d u c e d d i r e c t l y in one pro

cess, i f one is l u c k y , o r in several successive processes.

108 Form factors

Figure 101 Two versions of control wfieels in a pfiotocopier. In tfie prototype tfie wfieel is turned and milled (left), wfiile in tfie final version it is die-cast (rigfit). (Courtesy of Zeuthen & Aagaard Ltd.)

T h e economics o f t h e m a n u f a c t u r e depend o n w h i c h and h o w m a n y processes mus t be gone t h r o u g h befo re the ob jec t is f i n i shed . One mus t also cons ider t he necessary t r anspo r t , hand l i ng and ' f i x i n g s ' between t he separate processes.

T h e ava i lab i l i t y o f t h e desired mater ia ls mus t be e x a m i n e d . I t shou ld be dec ided w h e t h e r t h e y can be b o u g h t in t he requ i red f o r m , and unde r w h a t c o n d i t i o n s , o r w h e t h e r t h e c o m p a n y i tsel f m u s t p roduce t h e m .

T h e q u a n t i t y in w h i c h t h e ob jec t is t o be p r o d u c e d is decisive w h e n dec id ing w h i c h m a n u f a c t u r i n g processes w i l l be e c o n o m i c . Processes t h a t requ i re b ig investments in too l s and m a c h i n e r y (e.g. d ie cast ing and d r o p fo rg ing ) can o n l y be cons idered where large numbers o f ob jec ts are i nvo l ved , w h i l e those processes t h a t are i m m e d i a t e l y avai lable (e.g. t u r n i n g , m i l l i n g and we ld i ng ) are we l l su i ted t o t he p r o d u c t i o n o f single ob jec ts o r series o f ob jec ts . F igure 101 shows an examp le o f th i s .

As a l ready m e n t i o n e d , t h e last th ree fac to rs —

m a c h i n e r y , i nves tmen t in n e w m a c h i n e r y and special t oo l s - are c losely c o n n e c t e d w i t h the quan t i t i es t o be p r o d u c e d .

77?̂ manufacturing process: tfie operator

A t t he same t i m e as an ob jec t is designed a n d a p ro cess dec ided o n , a j o b f o r an ope ra to r is la id d o w n . Th i s m u s t be done as a consc ious e f f o r t , whe re t h e opera to r ' s s i t ua t i on is used t o i n f l uence t h e f o r m design and t h e cho ice o f process. One mus t ensure t h a t t he ope ra to r can ca r ry o u t t h e process app ro p r i a te l y w i t h o u t unnecessary w o r k load a n d r isk a n d , f o r instance, w i t h o u t unnecessary demands f o r p rec is ion o r speed.

B u t even i f in p r i nc ip le t h e ope ra to r ' s c o n d i t i o n s m a y be a l l owed f o r , the re is s t i l l a decisive f a c t o r rema in i ng . Has t h e c o m p a n y t h e necessary k n o w - h o w , can o thers be t r a i n e d , o r m u s t n e w w o r k e r s be e m p loyed?

Form factors 109

77?̂ manufacturing process: tfie economics of tfie detailed design

A f t e r t he f o r m c o n c e p t and the m a n u f a c t u r i n g p rocess are chosen acco rd ing t o t he c r i te r ia o f f eas ib i l i t y , economics and ope ra to r s i t ua t i on there is s t i l l t h e deta i led design t o be dec ided (see F igure 9 4 ) . T h e last task is t o design t he detai ls in such a w a y t h a t the ob jec t can be m a n u f a c t u r e d in the mos t su i tab le w a y by the chosen process, and t h a t t he desired f u n c t i o n m a y be s u f f i c i e n t l y we l l real ised.

F o r m design guidel ines f o r all t he usual processes can be f o u n d in the special ist l i t e ra tu re , and therefo re the character is t ics o f t he var ious processes w i l l n o t be discussed here. A f e w general gu idel ines can .

howeve r , be la id d o w n w i t h a v iew t o as e c o n o m i c a f o r m design as possib le. T h e y are :

n u m b e r and na tu re o f ' f i x i ngs ' , n u m b e r and na tu re o f t oo l s , n u m b e r and e x t e n t o f processes, access ib i l i ty f o r t oo l s , c o n s u m p t i o n o f mater ia ls .

These guide l ines are i l l us t ra ted in F igure 102 t o 106 . F igure 107 shows a c o m p l e t e examp le in w h i c h m a n y o f t h e e c o n o m i c a l l y i m p o r t a n t fac to rs are m e n t i o n e d .

ECONOMICS: Number and nature o f ' f i x i n g s '

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Figure 102 Form designs that ta/<e into account the economics of production

110

E C O N O M I C S : N u m b e r a n d n a t u r e of too ls

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Figure 103 Form designs that take into account the economics of production

ECONOMICS: N u m b e r and e x t e n t of processes

111

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Figure 104 Form designs that ta/ce into account the economics of production

112

ECONOMICS: Accessib i l i ty for too ls

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Figure J 05 Form designs that take into account the economics of;fig:^uction

ECONOMICS: Consumpt ion of m a t e r i a l s

F/^¿/re 106 Form designs that take into account the economics of production

113

5 OOP pieces a year

s ta r t ing ma te r i a l :

m a n u f a c t u r e :

c o n s u m p t . o f m a t e r i a l :

i nves tmen t :

p r o d u c t i o n cos t :

50 OOP pieces a year



C o n s u m p t i o n o f m a t :

i nves tmen t :

p r o d u c t i o n cos t :

2PP PPP pieces a year

P2P brass r o d

t u r n i n g th read c u t t i n g m i l l i n g

ob jec t 2 5 gr. shavings 7P gr.

n i l

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ob jec t 2 5 gr. shavings 25 gr.

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c o n s u m p t i o n o f m a t e r i a l :

i nves tmen t :

p r o d u c t i o n cost :

12 m m hexagona l brass r o d 1.5 m m brass s t r i p

t u r n i n g th read c u t t i n g p u n c h i n g assembly

o b j e c t 2P gr -H 3 gr shavings 2P gr c u t 2 gr

£36PP

2 5 p

Figure 107 Three versions of a thread spindle corresponding to different product quantities. The most important economic factors are listed

114 Form factors

Assembly

T h e close c o n n e c t i o n be tween the assembly process and the m a n u f a c t u r i n g processes was m e n t i o n e d o n page 105 and is i l l us t ra ted in the f o l l o w i n g examples . The assessments t h a t mus t be made before choos ing an assembly process are (as in the case o f t h e m a n u f a c t u r i n g process) feas ib i l i t y , economics and s i tu a t i o n o f the ope ra to r , and t h e fac to rs are c o m p l e t e l y paral le l t o t he fac to rs in choos ing the m a n u f a c t u r i n g process (see pages 1 1 0 - 1 1 2 ) . F igure 108 shows examples f r o m a p h o t o c o p i e r where t he p r o t o t y p e and the f ina l mach ine are c o m p a r e d . T h e i l l us t ra t i on shows, above, an examp le o f t h e w a y in w h i c h t he n u m b e r o f opera t ions in f i t t i n g a m i r r o r can be reduced i f one goes t o t he expense o f a die cast t o o l .

The l owe r i l l u s t ra t i on shows an examp le o f h o w a t r a d i t i o n a l w a y o f f i t t i n g a p i n can be s i m p l i f i e d i f the assembly process is ca re fu l l y t h o u g h t o u t .

A f t e r t he assembly process has been chosen (and the m a n u f a c t u r i n g ones as we l l ) t he p r o d u c t deta i ls mus t be designed in such a w a y t h a t an o p t i m u m assembly can be achieved. As a check t he f o l l o w i n g l ist o f general sub-opera t ions in assembly m a y be used:

recognise grasp move t o c o n t a c t area o r i en ta te

l ine up f i t in move a long c o n t a c t area secure

PROTOTYPE F I N A L VERSION

M i r r o r

Cl ip

Cog w h e e l Loose p in

Figure 108 Comparison between form design details in a prototype (function model) and the final version of a photocopier. Above, fixing a mirror to a frame; below, fixing a cog wheel on an axle (Courtesy Zeuthen & Aagaard Ltd.)

Form factors 115

F igure 109 shows examples o f the w a y in w h i c h some sub-opera t ions can be made easier by t he f o r m design. These cons idera t ions app l y w h e t h e r the assembly is manua l o r a u t o m a t i c . F igure 110 shows t he assembly o f a s top b u t t o n in an e lec t r i c

s w i t c h . O n t he b u t t o n is p r i n t e d t he w o r d S T O P , and in o rde r t o ensure t h a t i t is p u t on t he r igh t w a y u p , t he b o t t o m is designed w i t h a groove t h a t corresponds t o a k n o b o n t h e edge o f t he ho le .

ASSEMBLY :

To ease o r i e n t a t i o n

To ease inser t ion

(

'/////•'/,

I ! 1 i

Figure 109 Form design details that illustrate how the assembly is taken into account

Figure 110 Form design details that ensure a stop button is fitted in the correct position (Danfoss Ltd.)

116 Form factors

3.5 Sales and distr ibut ion factors

Factors t ha t in f luence d i s t r i b u t i o n and sales con s t i t u te a large and m i x e d g roup made up pa r t l y o f t he phys ica l c o n d i t i o n s such as packaging, pack ing , t r anspo r t and warehous ing , pa r t l y o f m a r k e t con d i t i ons and p a r t l y o f t he sales s i t ua t i on o f t h e c o m p a n y .

T r a n s p o r t cons idera t ions mean t h a t one mus t t h i n k a b o u t possible results o f shocks and shak ing . Del icate parts m a y have t o be secured; d a m p , d i r t , c o r r o d i n g f umes , etc mus t also be cons idered . I f t h e we igh t o f t h e p r o d u c t can cause p rob lems i t m a y be necessary t o d iv ide big heavy parts i n t o smal ler e lements. One mus t also check on w h e t h e r the

d imens ions o f t he p r o d u c t are t o o great f o r i t t o be e c o n o m i c a l l y t r anspo r ted and o n w h e t h e r , f o r ins tance, i t can pass t h r o u g h a d o o r .

A n examp le o f t he w a y in w h i c h a su i tab le f o r m design can make f o r conven ien t t r a n s p o r t m a y be i l l us t ra ted b y t h e l awn m o w e r in F igure 1 1 1 . B y fa r t h e biggest par t o f such a l awn m o w e r is t he hand le , w h i c h i f made in one piece w o u l d take up a disp r o p o r t i o n a t e a m o u n t o f space. Th is was, i ndeed , t he case in m a n y ear ly mode ls . A s o l u t i o n t o th i s p r o b l e m m a y be seen in t h e i l l u s t r a t i o n , as t h e hand le is d i v i ded in t w o places, so t h a t i t can be packed w i t h o u t t a k i n g u p m o r e r o o m t h a n t h e c u t t i n g u n i t .

Figure 111 Lawn mower where the handle is divided in two places solely for reasons of packaging and trans

port (Courtesy of Ginge Fabrikker Ltd)

Form factors 117

Mat ters t o be t a k e n i n t o accoun t in wa rehous ing nnay, f o r instance, be reduc ing the space o c c u p i e d , nnininnising t h e s e n t i t i v i t y o f t he p r o d u c t t o d a m p and d i r t etc, and t o ensure t h a t several ob jec ts o f t he same sor t can be s tacked. F igure 112 shows h o w s to r ing c o n d i t i o n s can i n f l uence the design o f p last ic buckets . There are here t w o p rob lems in c o n n e c t i o n

w i t h s torage, o n t he one hand t h e ob jects mus t take u p as l i t t l e space as possible ( i .e. t h e y m u s t be stack-ab le ) , and o n t h e o t h e r h a n d , t h e y m u s t be easy t o separate. A l t e r a t i o n o f t he angle gives m o r e c o m p a c t s tack ing . Squash ing in t he stack can be p reven ted by a ver t ica l r i b .

A l t e r a t i o n of a n g l e g i v e s m o r e c o m p a c t s t a c k i n g ;

S q u a s h i n g in t h e s tack can be prevented by α ver t ica l r i b :

Figure 112 Form design details on a plastic bucke t, where storage is taken in to accoun t (Courtesy Superfos Emballage L td.)

Ί 1 8 Form factors

o f i rons f r o m d i f f e r e n t per iods. Here t he shape o f t h e f u n c t i o n a l sur face against t he mater ia l has been preserved a lmos t una l te red t h r o u g h t h e ages. Th is shape has t w o character is t ics , f i r s t t h a t i t cons t i t u tes a f l a t , s m o o t h surface area against t he ma te r i a l , in o rder t h a t th is m a y i tsel f be made s m o o t h , and second ly t h a t i t is p o i n t e d so t h a t t he mater ia l is spread o u t be fo re i t is pressed s m o o t h .

N e x t , let us l o o k at t h e i n f l uence o f f u n c t i o n o n the f o r m . F u n c t i o n s can be f o u n d at m a n y levels in a p r o d u c t and t h e m a i n f u n c t i o n m a y t hus a f f ec t t h e t o t a l f o r m o f t he p r o d u c t and t h e sub - func t i ons the f o r m o f t he e lements . T h e i n f l uence o f t h e func t i o n s is, however , ve ry dependen t o n t h e i n t e n d e d f u n c t i o n s . In cer ta in cases the re is an unamb igous c o n n e c t i o n be tween f u n c t i o n and f o r m , as f o r instance in the cam and t he m i r r o r in F igure 114 ( t o p ) .

In o t h e r cases a cer ta in c o n n e c t i o n ex is ts , even t h o u g h there is some f r e e d o m . T h e p rope l l e r and the t h r e a d are examples o f th is . F i n a l l y the re are s i tua t ions where the re is no c o n n e c t i o n be tween t h e f u n c t i o n and t he f o r m , as f o r instance, the case r o u n d a me te r o r a c o m p u t e r .

3.6 Factors concerning the p ioduct in use

Process evaluation: Input, output and function

When a p r o d u c t is be ing used t he user o f t he p r o d u c t achieves a desired process (see also page 6 ) . Such a process m a y , f o r instance, be the d r i l l i n g o f holes (e lectr ic d r i l l ) , t he m i n c i n g o f meat (meat m i n c e r ) , t he m o v i n g o f wa te r ( p u m p ) and t h e m o v i n g o f f o o d ( f o r k ) . Th is is t he f u n c t i o n o f t he p r o d u c t ( the ma in f u n c t i o n , see also page 9 ) ; o n e can t h i n k o f t he usage and t he f u n c t i o n as t w o sides o f the same c o i n ; the usage may be descr ibed by the ob jec t t h a t alters a c o n d i t i o n , w h i l e the f u n c t i o n describes the s imu l taneous o p e r a t i o n o f t he p r o d u c t (or t o o l ) . We thus get p r o d u c t fac to rs f r o m b o t h t he ob jec t — in t h e s ta r t ing state these are cal led i n p u t and in t he f i na l state o u t p u t - and f r o m th is f u n c t i o n .

I f we f i r s t examine the in f luence o f i n p u t and o u t p u t o f the f o r m design o f a p r o d u c t we m u s t remember t h a t t h e areas where i t is in c o n t a c t w i t h its su r round ings are the ex te rna l f u n c t i o n a l surfaces (see page 4 8 ) . I t is o n these surfaces t h a t i n p u t and o u t p u t have the i r greatest i n f luence . Count less examples o f such an in f luence may be m e n t i o n e d , f o r examp le , nuts t h a t a f fec t the f o r m o f an open-ended or a b o x spanner, a p u n c h i n g t o o l t h a t t ransfers its f o r m t o the ob jec t , etc. F igure 113 shows a n u m b e r

119

Figure 113 Irons from different periods. The functional surface which rubs against the material in all these designs is unchanged. (The two lower illustrations are by courtesy of Rowenta and Philips)

120

Figure 114 Interaction between function and form. Above, absolute connection; centre, a certain degree of connection; below, no connection

Process realisation: Realisation of tfie function

Form factors 121

I t is obv ious t h a t t o mere l y state there is a m o r e o r less close c o n n e c t i o n be tween f u n c t i o n and f o r m , as descr ibed p rev ious ly , is n o t pa r t i cu l a r l y cons t r uc t i ve , b u t a desc r i p t i on o f t he fac to rs t h a t c o m e i n t o p lay m a y i l l u m i n a t e i m p o r t a n t p rob lems f o r t h e designer. T h e f u n c t i o n a l fac to rs m a y be d i v i ded i n t o t w o categor ies:

rea l isat ion q u a l i t y o f f u n c t i o n .

T h e f o r m e r m a y invo lve such fac to rs as: f u n c t i o n in terva l (can the f u n c t i o n be realised in t h e desi red size?) q u a l i t y o f t h e o u t p u t exactness (prec is ion) capac i t y speed o f t h e process ef fect iveness. Examples o f t h e dependence o f some o f these

fac to rs o n t h e f o r m o f t h e f u n c t i o n a l surfaces are s h o w n in F igure 115 .

UNLOADING MAGAZINE IN TEST TUBE MACHINE

The glasses run up and f a l l down

BENDING TOOL FOR A COIL

In terrupt ing pro ject ions give s m o o t h f i l l m g

Shape of co i l unacceptable

Shape of coil good

Figure 115 Examples of the way in which the feasability of a desired function is tied in with the form design of a functional surface. Above, an unloading magazine in a test tube machine (see also Figure 53); below, a bending tool for a coil of thick

copper wire

122 Form factors

These fac to rs can be t a k e n i n t o a c c o u n t by choos ing and bu i l d ing - in su i tab le qua l i t ies such as:

s t reng th r i g i d i t y hardness e las t i c i t y , e tc . F igure 116 shows examples o f f o r m designs t h a t

t ake t h e above -men t i oned q u a l i t y o f f u n c t i o n fac to rs i n t o c o n s i d e r a t i o n .

Fiaure 116 1 A bolt where deeper bends reduce the slot sensitiv i tity. 2. Connection between mo mechamcal parts fbere the sJmbly is most rigid if th^ through the middle 3 and 4. Form designs that g,ve

strength. 5 and 6. Form designs that provide rigidity (a truck body and supporting frame for a diesel engineer)

Process realisation: Quality of tfie function

When i t has been dec ided t h a t a given f u n c t i o n is possible, t h e n e x t stage is t o establ ish under w h a t c o n d i t i o n s th is w i l l be d o n e a n d t h e e x t e n t t o w h i c h t h e desired f u n c t i o n can be ach ieved. The f u n c t i o n a l fac to rs at th is stage m a y be cal led q u a l i t y o f f u n c t i o n fac to rs , f o r e x a m p l e :

is t h e f u n c t i o n rep roduc ib le parameter sens i t i v i ty re l i ab i l i t y safety s tab i l i t y .

User or operator: A survey of tfie factors

Form factors 123

T h e user na tu ra l l y demands cer ta in th ings o f t h e p r o d u c t . One o f t he mos t f u n d a m e n t a l o f these is t h a t t he p r o d u c t mus t be s imple t o use, i.e. t h a t its use mus t be easy and u n c o m p l i c a t e d w i t h the least possible men ta l and phys ica l e f f o r t .

In o rder t o take adequate a c c o u n t o f such requ i remen ts the designer mus t acqui re — o r at least be able t o f i n d - i n f o r m a t i o n o n t he d imens ions , senses, pe r cep t i on , muscu lar pe r f o rmance , t i r ed ness, etc o f t he h u m a n b o d y . I f there are special categories o f users, such as hand icapped peop le , c h i l d r e n , etc, special a t t e n t i o n mus t be given t o th is i n f o r m a t i o n . I t is t h e n the designers j o b t o u t i l i se

th is know ledge toge the r w i t h a general app rec ia t i on o f t he i n te rp l ay be tween ' m a n and the m a c h i n e ' ( w h i c h is covered in e rgonomics ) , so t h a t t he p r o d u c t is designed as su i t ab l y as possible. I f a designer overl ooks th is very i m p o r t a n t b a c k g r o u n d know ledge the resul t is o f t e n a p r o d u c t t h a t m a y be e i the r d i f f i c u l t t o use, o r gives a bad w o r k i n g pos tu re (and restu lg ing in back t r o u b l e ) , o r t h a t m a y h o l d risks o f w r o n g o p e r a t i o n , etc . A n examp le is s h o w n in F igure F igure 117 . Here t he design o f t h e la the is such t h a t an o p e r a t o r w i t h n o r m a l b o d y d imens ions c a n n o t avo id an unreasonable pos tu re , w h i c h puts a great s t ra in o n his back.

Figure 117 A lathe in which the design does not take into account the requirement of a good working posture

124 Form factors

Figure 118 shows an exannple o f a p r o d u c t where t he design takes t he greatest possible accoun t o f t h e user's s i t u a t i o n . T h e noise meter is b u i l t so t h a t at t he t o p there is a d i rec t iona l m i c r o p h o n e w h i c h p icks u p and records t h e noise c o m i n g i n . T h e t o p par t o f t he i n s t r u m e n t a lmos t a b o t t l e n e c k t o avo id re f lec t ing surfaces t h a t m a y have an e f fec t o n t h e exac t i t ude o f t he m i c r o p h o n e .

T h e noise me te r is also designed so t h a t i t is c o m f o r t a b l e t o h o l d w h e n me te r ing . Hand l i ng is t aken i n t o cons ide ra t i on by a su i tab le a r rangement o f such e lements as c o n t r o l knobs , d ia ls, etc. These are designed in such a w a y t h a t t h e y are easi ly accessible w h e n the i n s t r u m e n t is d i rec ted t o a given noise source.

T h e i n t e r a c t i o n be tween m a n and t he mach ine w i l l n o w be s tud ied m o r e c lose ly . We can t h i n k o f a mach ine and an ope ra to r as a sys tem t h a t can act o n t he su r round ings in a desired w a y , i.e. t o make use o f t he p r o d u c t . F igure 119 shows such a m a n / m a c h i n e sys tem, where t h e i n te rp lay be tween t he mach ine and t h e ope ra to r and be tween t h e m and t he surround ings is s h o w n .

T h e i n t e r a c t i o n be tween t h e mach ine and t h e o p e r a t o r m a y be d i v i ded i n t o f o u r categor ies, in vo l v i ng a n u m b e r o f f ac to r s :

hand l i ng c o n d i t i o n s in c o n n e c t i o n w i t h instal l a t i on and r u n n i n g i n . n o r m a l o p e r a t i o n , e.g. na tu re o f j o b , good w o r k i n g pos tu re , sa fe t y , easy m o v e m e n t s and access ib i l i t y . occasional o p e r a t i o n , e.g. c lean ing , ma in tenance , ad jus tmen ts and repairs. emergency o p e r a t i o n , e.g. emergency s top and f i r e . A p a r t f r o m these f o u r categories w h i c h conce rn

t h e o p e r a t i o n o f t h e mach ine unde r var ious c i r c u m stances the re are f o u r add i t i ona l categor ies, t h a t have no d i r ec t c o n n e c t i o n w i t h t he o p e r a t i o n . T h e y are :

c i rcumstances ou ts ide d i rec t o p e r a t i o n , e.g. i n s ta l l a t i on , m o b i l i t y , storage space, economics , e.g. in i t i a l cos t , r u n n i n g costs, dep rec i a t i on , user requ i remen ts , e.g. advance k n o w l e d g e , in s t r u c t i o n , t r a i n i n g , e d u c a t i o n , sub ject ive c i rcumstances , e.g. psycho log ica l c i rcumstances in ope ra t i ng t h e mach ine , appearance.

F r o m the above e ight categor ies, t h e f o l l o w i n g have a close c o n n e c t i o n w i t h t h e f o r m : n o r m a l o p e r a t i o n , occasional opera t ions and subject ive c i rcumstances . These w i l l be f u r t h e r s tud ied in t he f o l l o w i n g sec t i on .

Figure 118 A noise meter designed with consideration of the circumstances under which

it will be used

Form factors 125

SYSTEM

MACHINE J OPERATOR

J SURROUNDINGS

Figure 119 l\^a η/machine system

User or operator: Normal operations

A m o n g the fac to rs w h i c h conce rn the n o r m a l o p e r a t i o n o f t he mach ine m u s t be m e n t i o n e d :

na tu re o f t he j o b ( a i m : a mean ing fu l j o b ) , good w o r k i n g pos tu re , sa fe ty , easy movemen ts , access ib i l i ty , conven ien t c o m m u n i c a t i o n w i t h t he mach ine , no unpleasant noise, heat , re f lec t ions , etc.

T h e th ree fac to rs o f w o r k i n g pos tu re , movemen ts and accessib i l i ty are c losely t i ed in w i t h the design. Th is is p r i m a r i l y a ques t i on o f t a k i n g accoun t o f t he h u m a n d imens ions and pe r f o rmance poss ib i l i t ies , so t h a t one can avo id bad ly designed p roduc t s such as t he la the in F igure 117 . There are a n u m b e r o f books o n e rgonomics and a n t h r o p o m e t r y (i .e. t he s t u d y o f t he measurements o f t he h u m a n b o d y ) w h i c h cover th is subject .

C o m m u n i c a t i o n be tween t he ope ra to r and t h e mach ine involves m a n y design aspects t h a t are w o r t h y o f f u r t h e r e x a m i n a t i o n . W i t h o u t su i tab le c o m m u n i c a t i o n t he p r o d u c t c a n n o t be used as des i red. When i n f o r m a t i o n is conveyed f r o m one place t o ano the r there is a lways the r isk o f e r ro r . Th is can happen in t w o ways , as s h o w n in F igure 120 . O n

Figure 120 The two possibilities for errors in transferring information from A to Β

t he one hand i n f o r m a t i o n m a y be lost , o r w r o n g i n f o r m a t i o n m a y be added . T h e f o l l o w i n g pages ou t l ine a n u m b e r o f c i rcumstances t h a t can c o n t r i b u t e t o clear an unamb igous c o m m u n i c a t i o n be tween t h e o p e r a t o r and t h e mach ine .

Let us take as o u r s ta r t ing p o i n t t h e m a n / m a c h i n e sys tem in F igure 119 . A m o r e de ta i led m o d e l is s h o w n in F igure 1 2 1 . T h e ope ra to r can , in p r i nc ip l e , be t h o u g h t o f as c o m p r i s i n g th ree sub-systems, n a m e l y t h e sensory appara tus (eyes, ears, e t c . ) , t h e dec is ion appara tus ( the b ra i n ) , and m o t o r apparatus (hands, arms and legs). T h e mach ine m a y be d i v i ded in t he same w a y i n t o th ree sub-systems; t h e process s y s t e m , t he superv is ion sys tem and t he ope ra t i ng sys tem.

126 Form factors

Γ

M A N / M A C H I N E S Y S T E M

M A C H I N E

"supervisión p system ^

Process ρ system Λ

Opera t i ng

O P E R A T O R

Sensory apparatus

Dec is ion apparatus

M o t o r apparatus

I

Figure 121 The most important elements and relationships in a man/machine system

Those parts o f t he mach ine w h i c h are in d i rec t c o m m u n i c a t i o n w i t h the ope ra to r ( the ha tched areas in t h e f i gu re ) are k n o w n as the supervis ions area, t h e opera t ing area and the open process area. The m u t u a l i n f l uence be tween t h e sub-systems is demons t ra ted in t he i l l u s t r a t i on . T h e th ree areas are s y m b o l i c a l l y

i l l us t ra ted in F igure 122 . Superv is ion areas and ope ra t i ng areas are o f t e n p laced toge the r in a c o n t r o l area, w h i l e t he open process area is k e p t apar t f r o m these. Examples o f t he a r rangemen t o f t he areas are s h o w n in F igure 123 and 124 .

C o n t r o l area

Figure 122 The three areas of a machine with which the operator is in contact

127

Figure 123 Control area and open process area in a grinding machine and a hydraulic press

128

Figure 124 Control area and open process area in a copying camera and an electric cooker (Courtesy of Esk o fot Ltd. and S.A.G. Ltd)

Form factors 129

O n a mach ine , t he c o n t r o l areas and t h e open process area shou ld be arranged in such a w a y t h a t t h e y are c lear ly separated. Th is is he lp fu l t o t he opera to r and fu r t he rs c o m m u n i c a t i o n be tween h i m and t he mach ine . Somet imes t he c o n t r o l area is p laced in a separate u n i t w h i c h is phys ica l l y apar t f r o m the mach ine . Th is m a y e i ther be due t o a natura l f u n c t i o n a l separa t ion , as e.g. in n u m e r i c a l l y c o n t r o l l e d mach ine t oo l s , where the c o n t r o l u n i t is separate f r o m t h e rest, o r i t m a y also be because speci f ic advantages in use m a y be ga ined. T h e la t te r m a y be q u i c k e r and m o r e conven ien t hand l i ng , t he poss ib i l i t y o f r emo te c o n t r o l , greater safety f o r t he ope ra to r o r perhaps o n l y greater f l e x i b i l i t y all r o u n d . A n examp le is s h o w n in F igure 125 .

O n t h e o t h e r h a n d , i f t h e c o n t r o l area is p laced in o r o n t he mach ine i t m a y be emphasised in var ious ways . A n i m p o r t a n t f a c t o r in th is c o n n e c t i o n is t he so-cal led ' f igure o n g r o u n d e f f e c t ' , w h i c h is a f u n d a menta l e f fec t in any visual p e r c e p t i o n . T h e ' f igure o n g r o u n d e f f e c t ' tel ls us t h a t w h e n w e l o o k we a lways no t i ce objects o r f igures, w h i c h t h e r e b y bec o m e s ign i f i can t , w h i l e the b a c k g r o u n d dw ind les and perhaps ha rd l y leaves a t race in o u r consciousness. I f one wants t o d r a w a t t e n t i o n t o s o m e t h i n g , i t m a y thus be done b y us ing a f igure t h a t stands o u t c lear ly against t h e b a c k g r o u n d . O n the basis o f these facts one can f o r m u l a t e some requ i remen ts f o r t he design o f t he c o n t r o l area:

T h e con t ras t in f o r m , c o l o u r and surface ( t e x t u r e ) be tween t he f igu re and t he b a c k g r o u n d m u s t be

o p t i m i s e d . Th is does n o t mean t h a t t he con t ras t m u s t be as great as possible ( b l a c k / w h i t e , r e d / green e tc . ) as th is m a y make eve ry th i ng seem t o f l i c ke r . O n t he c o n t r a r y , i t means t h a t t he con t ras t mus t be adap ted so t h a t t he f igure stands o u r c lear ly f r o m t h e b a c k g r o u n d w i t h o u t d i s t rac t i ng and t i r i n g t he eye.

D imens ions be tween t he i nd i v idua l f igure and t h e rema in i ng f igures m u s t be ad jus ted . There m u s t n o t be f igures t h a t get lost in t h e c r o w d .

G o o d l i gh t i ng mus t be assured.

D i s t r ac t i ng e lements m u s t be m i n i m i s e d . These m a y be e.g. re f l ec t i ons , a f te r images, p o w e r f u l sources near and d o m i n a t i n g f igures very close t o .

F igure 126 shows a p h o t o c o p i e r where the f igure g r o u n d e f fec t is u t i l i sed t o emphasis t h e c o n t r o l area and make i t c lear.

T h e i nd i v i dua l e lements o f a c o n t r o l panel con -s t u t u t e t w o categor ies, name ly t he s ignal l ing i n s t r u m e n t s ( the superv is ion area) and t h e ope ra t i ng i ns t rumen ts ( the o p e r a t i n g area). We have prev ious ly seen h o w t h e mach ine m u s t be designed in such a w a y t h a t t he c o n t r o l areas s tand o u t as a clear and we l l de f i ned pa r t o f t he mach ine . T h e f o l l o w i n g pages o u t l i n e some pr inc ip les f o r ar rang ing t he ind iv idua l c o m p o n e n t s o f t h e c o n t r o l panel w i t h regard t o effec t i ve c o m m u n i c a t i o n be tween the o p e r a t o r and the mach ine .

T h r e e m a i n p o i n t s man i fes t themselves in t h e layo u t o f a c o n t r o l pane l , name ly the f r e q u e n c y o f use

Figure 125 Electric scales, where the control area is separate from the process

area (the tray). (Courtesy of Bizerba)

130 Form factors

Figure 126 A photocopier with the control emphasised (Courtesy Oce-Helioprint Ltd)

and t h e innportance o f t he separate elennents, as we l l as t he c l a r i t y o f t h e l a y o u t . Th is means t h a t t h e mos t o f t e n used e lements , a n d , f o r ins tance, an emergency s top are p laced c e n t r a l l y . W h i l e , genera l l y , i t is n o t d i f f i c u l t t o dec ide w h i c h e lements be long t o t h e t w o f i r s t - m e n t i o n e d groups i t is a m o r e d e m a n d i n g task t o arrange t h e e lements in re la t i on t o each o t h e r in a manne r t h a t is c lear and s imp le t o grasp. Here, h o w ever, pe r cep t i on p s y c h o l o g y m a y he lp us, especia l ly t h e b ranch ca l led gestal t p s y c h o l o g y . T h e m o s t i m p o r t a n t fac to rs in th i s c o n n e c t i o n are t h e ideas o f g r o u p and p a t t e r n c rea t i on o n t he basis o f closeness and s i m i l a r i t y .

O n c o n t r o l panels w i t h m a n y s im i la r e lements , e.g. l igh ts , swi tches and handles, i t is usefu l t o d i v i de these i n t o smal ler g roups t h a t are easy t o scan. Va r i ous means m a y be used f o r t he g r o u p i n g , name ly e i ther co l l ec t i ng t he e lements i n t o smal ler groups by ar rang ing t h e m closer t oge the r , o r d i f f e r e n t i a t i n g t h e m by g roups , e.g. each g r o u p its o w n c o l o u r . I t is also possib le, o f course t o f o r m groups by d i v i d i n g the area o f t he c o n t r o l panel i n t o d i f f e r e n t sect ions w i t h t h e a id o f l ines and co lou rs .

F igure 127 shows schemat i ca l l y a c o n t r o l panel w i t h 5 0 e lements . I f these are arranged as in (a) , t h e y w i l l f o r m an area o f a u n i f o r m s t r u c t u r e , where i t is d i f f i c u l t t o i d e n t i f y a given e lement . In (b) t o (e) t h e

O O o o o o o o o o o o o o o

o o o o o

Figure 127 A control panel with many similar elements

131

Figure 128 Grouping the elements on the background of closeness and similarity (Courtesy IBM)

Figure 129 An element that stands out in an otherwise homogeneous row catches the attention. The picture showspart of a control panel on a computer (Courtesy IBM)

132 Form factors

Figure 130 A control panel with groups formed on the basis of proximity, similarity and framed sections (Courtesy DISA Electronic Ltd)

g roup ing is done respect ive ly by d i f f e r e n t d is tance, t h e m . F igure 128 shows y e t ano the r examp le o f th i s , d i f f e r e n t c o l o u r , d iv is ion by l ine and d iv i s ion b y I f , o n a c o n t r o l pane l , there is a r o w o f s im i la r co l ou red areas. These d iv is ions mean t h a t one can e lements t h e y w i l l be perceived asa h o m o g e n o u s r o w q u i c k l y — w i t h o u t c o u n t i n g — p o i n t t o a given ele- where no e lemen t stands o u t . One does n o t no t i ce m e n t . In o the r w o r d s , by g roup ing the e lements one the separate e lements . N o w , i f one o f these is can ensure m u c h qu i cke r i d e n t i f i c a t i o n o f the a l te red , i t w i l l at once be c lear ly d is t ingu ishab le f r o m separate e lements t h a t i f one had t o c o u n t t o f i n d the o thers . Th is fac t m a y be used in t w o w a y s ;

A r o w o f s imi la r e lements o u g h t t o have the same ' n o r m a l ' p o s i t i o n , i.e. al l po in te rs are ver t ica l and all l ights are o n d u r i n g o p e r a t i o n , etc. I f one o f the e lements gets o u t o f the no rma l pos i t i on i t w i l l i m m e d i a t e l y a t t r ac t a t t e n t i o n , and thus ensure t h a t the a l t e ra t i on is n o t i c e d . See F igure 129. I f one o f the e lements is especial ly i m p o r t a n t i t can be p laced in a r o w o f o thers t h a t are s imi la r t o each o the r . T h e one t h a t is d i f f e r e n t w i l l s tand o u t . As an examp le m a y be m e n t i o n e d a d ia l w i t h a d i f f e r e n t shape f r o m the o thers , o r a red emergency s top placed be tween b lack c o n t r o l knobs . G r o u p i n g b y f u n c t i o n is o f t e n used as a basis f o r

c o n t r o l panel l a you t . T h e e lements t h a t be long

Form factors 133

Figure 132 Process-determined layout of a control panel. The picture shows the control panel of a grass drying plant (Courtesy

of Atlas Ltd)

Figure 131 Operationally determined layout of a control panel. The elements of the panel are arranged in the order in which they must be operated (Courtesy

Watson-Marlow Ltd)

t oge the r in a f u n c t i o n a l u n i t are co l l ec ted in one g r o u p o n the pane l , e i ther by p lac ing t he e lements in t he i nd i v idua l f u n c t i o n a l groups c losely toge the r ( p r o x i m i t y ) , by m a k i n g t h e m s imi la r in f o r m or c o l o u r ( s i m i l a r i t y ) , o r by d i v i d i ng t h e panel i n t o sect ions ind ica ted by l ines, co lours or areas. A n examp le is s h o w n in F igure 130 .

A n o p e r a t i o n a l l y - d e t e r m i n e d l a y o u t o f a c o n t r o l panel m a y be exped ien t i f t he e lements are used each t i m e in a ce r ta in sequence. In th is case i t w i l l be na tu ra l t o place t he e lements in an o rder cor respond ing t o th is sequence, so t h a t by m o v i n g one's f ingers f r o m one b u t t o n t o t he nex t t he sequence is f o l l o w e d c o r r e c t l y (F igure 1 3 1 ) .

A process-de termined l a y o u t o f a c o n t r o l panel is

134 Form factors

User or operator: Occasional operations

Occasional opera t ions are act iv i t ies in c o n n e c t i o n w i t h the mach ine , w h i c h d o n o t conce rn the no rma l opera t ions , b u t w h i c h are necessary f o r t h e con t i n u o u s use o f i t . These are:

c lean ing, ma in tenance , serv ic ing, ad jus t ing , repairs.

H o w m u c h regard one shou ld pay t o these fac tors depends o n b o t h t h e p r o d u c t and t h e e n v i r o n m e n t . The designer mus t r e m e m b e r t o cons ider f r o m w h i c h po in t s o f v i ew t h e fac to rs s h o u l d be t a k e n i n t o accoun t , f o r ins tance, w h e t h e r t he p r o d u c t m u s t be easy t o c lean , o r w h e t h e r i t s h o u l d be designed so t h a t c lean ing is unnecessary. A l so w h e t h e r t he p r o d u c t m u s t be easy t o ad jus t and repai r , o r w h e t h e r i t mus t be b u i l t in such a w a y t h a t parts o r subsystems are replaced instead. Easy c lean ing is achieved f i r s t o f all by ensur ing easy access a n d by avo id ing slots and holes t h a t can co l l ec t d i r t (see Figures 133 and 134 ) . The rema in ing fac to rs are t a k e n i n t o cons ide ra t i on by a design w h i c h also gives access ib i l i ty , s imple assemb ly /d i sman t l i ng o f c o m p o n e n t s , conven ien t w e i g h t and size o f these and safety w h i l e p e r f o r m i n g these jobs .

Figure 133 Meat mincers with suction feet. On the left is a design where meat juices and liquid may run down into the foot which cannot be taken apart. On the right a new design where cleaning has been taken into consideration

natura l i f t he e lements o n t he panel c o n t r o l a n u m b e r o f c o m p o n e n t s in a process sys tem. T h e panel may in th is case, as s h o w n in F igure 132 , be designed as a s imp l i f i ed d iagram o f t he process w i t h the ind iv idua l e lements o n t he panel so arranged t h a t i t is easy t o see t o w h i c h p o i n t in t he process system t h e y correspond .

Form factors 135

Figure 134 Suggested designs for the ho/der of a dia/ysis ceil (artificial kidney). The equipment is used in a hospital environment, where easy cleaning is an important requirement. The design shown in the lower illustration is therefore preferable

136 Form factors

Figure 135 shows t w o mic roscopes f r o m d i f f e r e n t per iods , w h i c h b o t h give an aesthet ic exper ience . T h e par t i cu la r c o n d i t i o n s conce rned in aesthet ic design w i l l be discussed in greater deta i l in Chap te r 4 , w h i c h deals exc lus ive ly w i t h the appearance o f t he p r o d u c t .

I t is d i f f i c u l t t o d r a w the l ine be tween s ty le , fash ion and hab i t . Wh i le s ty le is a sor t o f c o m m o n d e n o m i n a t o r f o r w h a t is c u r r e n t in a ce r ta in p e r i o d w i t h regard t o t h e design o f p roduc t s in i n d u s t r y , app l i ed ar ts , a rch i tec tu re and a r t , f ash ion is sho r t l i ved and o f t e n a t t ached t o ce r ta in p r o d u c t s . T h u s the fash ion in cars, f o r instance, has n o t h i n g t o d o w i t h the fash ion in the design o f domes t i c appl iances. Figures 136 and 137 s h o w examples o f s ty le and fash ion .

A l so , hab i t mus t n o t be o v e r l o o k e d w h e n designing a p r o d u c t . I f the re is a w idespread hab i tua l idea o f w h a t t he design shou ld be, i t can be ca tas t roph ic f o r a c o m p a n y t o ignore th i s . One o f the best k n o w n

Figure 135 New and old microscopes. However, they both provide an aesthetic experience. (New microscope is by courtesy of Wild Heerbrugg Ltd.)

User or operator: Subjective circumstances

Some o f the mos t i m p o r t a n t and , at the same t i m e , mos t d i f f i c u l t fac tors in designing a p r o d u c t c o n cern the user's sub ject ive a t t i t u d e t o i t : ·

psycho log ica l facts , appearance.

T h e psycho log ica l facts conce rn t h e user's reac t ion t o the p r o d u c t ; the user m a y , f o r instance, feel repu lsed /a t t rac ted , u n s u r e / c o n f i d e n t , oppressed/ f ree wh i l e using i t (see F igure 1 9 0 ) . These fac tors m a y b e d i f f i c u l t t o assess at t he design stage, b u t i f one feels t h a t there m a y be p rob lems , a th ree-d imens iona l mode l m a y be needed.

F r o m the user's v i e w p o i n t t he appearance o f t he p r o d u c t plays an i m p o r t a n t ro le . When eva lua t ing the appearance d i f f e r e n t i a t i o n can be made be tween the aesthet ic e lemen t a n d the in f luence o f s t y le , fash ion and hab i t . T h e aesthet ic side is t imeless and universal beau ty , w h i l e s ty le , f ash ion and h a b i t depend o n t i m e and place.

Form factors 137

Figure 136 The influence of style on form illustrated by telephones and switches (Courtesy of G NT Automatic Ltd, and LK-NESLtd)

Figure 137 Fashion: Three makes of car having almost iden tical

designs

examples o f t he f o r ce o f hab i t is t h a t o f ships, w h i c h t h a t i t was t h o r o u g h l y researched b o t h t echn i ca l l y even t o d a y are m o s t l y b u i l t w i t h a f u n n e l , t h o u g h a n d o p e r a t i o n a l l y i t d i d n o t sel l , because t h e f o r m these became unnecessary w i t h t h e i n t r o d u c t i o n o f was t o o r e m o t e f r o m the t r a d i t i o n a l idea w h i c h the diesel engine. A n o t h e r examp le is t h e t rans is to r peop le had o f w h a t a t rans is to r rad io shou ld l o o k rad io s h o w n in F igure 138 ( l e f t ) . In sp i te o f t h e f a c t l i ke (F igure 1 3 8 , r i g h t ) .

138 Form factors

Environment

T h e e n v i r o n m e n t in w h i c h t he p r o d u c t w i l l be used is i m p o r t a n t f o r t he design in t w o ways . O n t he o n e hand t he e n v i r o n m e n t m a y have t o be p ro tec ted against t he ef fects o f t h e p r o d u c t and , o n t h e o the r , t he p r o d u c t m a y have t o be p r o t e c t e d against t he ef fects o f t h e e n v i r o n m e n t .

In cases where a p r o d u c t m i g h t poss ib ly damage or perhaps ru in t h e e n v i r o n m e n t t h e design m u s t be such t h a t th is does n o t happen . If a p r o d u c t is t o be d i r e c t l y ope ra ted by a user, one m u s t be aware o f t he in f luences t o w h i c h th is person is exposed t o and take these i n t o a c c o u n t in t he design. I f i t is a p r o d u c t

Figure 138 Habit. Two transistor radios showing traditional and unusual designs. The design on the right is immediately recognisable as a transistor radio (Courtesy Bang & Olufsen)

Figure 139 Two oil-fired boilers for different environments, namely a utility room which requires cleanliness and muffling anda cellar without particular requirements

t h a t w i l l be used in a f a c t o r y one m u s t t h e r e f o r e , t h r o u g h t h e design, ensure t h a t there is n o de te r io ra t i on o f t he w o r k i n g e n v i r o n m e n t . O b v i o u s l y , t h e same cons idera t ions mus t be s h o w n i f peop le , m a y have t o pass near the p r o d u c t . In t he instances m e n t i o n e d t h e p r o d u c t m a y have t o be sh ie lded against

Form factors 139

Figure 140 A pressure switch on three different covers to protect it from damp - normal, drip-proof and ray-proof

(Courtesy Danfoss Ltd)

heat , m u f f l e noise, d a m p v i b ra t i ons , e tc . A n examp le is s h o w n in F igure 139 .

T h e p r o d u c t is exposed t o a n u m b e r o f m o r e o r less u n c o n t r o l l e d in f luences such as h igh tempera tu res , c o r r o d i n g l i qu ids and gases, fo rces, v i b ra t i ons , etc . T h e r e f o r e i t m u s t be designed so t h a t i t can resist these fac to rs adequa te l y .

140 Form factors

T h e design is i n f l uenced by t h e cho ice o f mater ia l and consequen t l y by the cho ice o f m a n u f a c t u r i n g process. I t w i l l also be a f fec ted by t he possible need f o r special cove r ing , p ro tec t i ve shields, e tc . A n examp le is s h o w n in F igure 140 , where a pressure sw i t ch is designed f o r th ree d i f f e r e n t env i r onmen ts . A t t he t o p , is a no rma l sw i t ch f o r o r d i n a r y f a i r l y d r y rooms , in t he cen t re a design t h a t is d r i p p r o o f , i.e. p r o o f against d a m p and dus t , and at t he b o t t o m a ray p r o o f t y p e s w i t c h i.e. a c o m p l e t e l y enclosed and very t o u g h vers ion f o r use in specia l ly exposed loca t ions .

3.7 Destruction factors

The f i na l process t h a t a p r o d u c t goes t h r o u g h d u r i n g its l i f e ' (see page 6) is d e s t r u c t i o n . A l l p roduc t s are des t royed e i ther by a gradual b reak ing d o w n t h r o u g h env i r onmen ta l in f luences or by d e s t r u c t i o n by m a n , i.e. i n c i n e r a t i o n , c rush ing , m e l t i n g , c u t t i n g u p , etc. The d e s t r u c t i o n fac to rs can be d i v i ded i n t o env i r on m e n t cons idera t ions , possib i l i t ies f o r recyc l ing and the c o n s u m p t i o n o f resources in t h e d e s t r u c t i o n process.

E n v i r o n m e n t a l cons idera t ions m a y be decisive as t o w h e t h e r act ive d e s t r u c t i o n is c o n t e m p l a t e d . I f t he p r o d u c t , a f te r i t has served its purpose cons t i t u tes a danger, an eyesore or some o the r nuisance, i t m a y be designed in such a w a y t h a t i t is easy t o d i sman t le or des t roy , o r mater ia ls may be used w h i c h ensure t h a t t he natura l d e s t r u c t i o n is speeded up .

Possibi l i t ies f o r recyc l ing ma te r i a l , c o m p o n e n t s o r sub-systems o u g h t t o be cons idered in the design. Fo r instance i t m a y be t h a t a t i n y a l t e ra t i on in t he design makes possible a s imple d i sman t l i ng o f a given c o m p o n e n t o r an easy separa t ion o f t w o mater ia ls . As the supp l y o f ou r raw mater ia ls becomes shor te r i t m a y become more usual t o take th is f a c t o r i n t o accoun t .

The c o n s u m p t i o n o f resources in d e s t r u c t i o n is m a i n l y a ques t i on o f using m a n p o w e r , energy and e q u i p m e n t .

3.8 Evaluation or f o r m design suggestions

Obv ious l y n o t all t he f o r m fac to rs o r f o r m c r i te r ia p rev ious ly m e n t i o n e d can be f u l l y a c c o m o d a t e d in

a given s o l u t i o n . When eva lua t ing a n u m b e r o f f o r m design suggestions (see Chap te r 2 o n ' F o r m synthesis m e t h o d s ' ) one gets a s i t u a t i o n whe re t he d i f f e r e n t suggestions f u l f i l l t he c r i t e r ia in d i f f e r e n t ways . T h e p r o b l e m may be i l l us t ra ted by t h e f o l l o w i n g examp le . W h i c h o f t w o suggested so lu t i ons is t he best one , w h e n one s o l u t i o n is cheap t o p r o d u c e , re la t i ve ly c o m p l i c a t e d t o opera te , expensive t o r u n and o f g o o d appearance, w h i l e t he o t h e r s o l u t i o n is dearer t o p r o d u c e , easy t o opera te , cheap t o r u n and o f an u n f o r t u n a t e appearance? T h e answer m u s t na tu ra l l y depend o n w h a t o t h e r c r i te r ia shou ld also be t a k e n i n t o accoun t , as we l l as w h a t w e i g h t t he i nd i v i dua l c r i t e r i a m u s t be given c o m p a r e d t o each o the r . T h e eva lua t ion o f a n u m b e r o f suggested so lu t i ons is t h e r e f o r e a d i f f i c u l t task .

Eva lua t ion m a y be car r ied o u t by a n u m b e r o f m o r e o r less f o rma l i sed techn iques . These r u n f r o m a qu i t e i n f o r m a l eva lua t ion based o n i n t u i t i o n t o one w i t h several balanced c r i t e r ia t h a t are we ighed separate ly , a f te r w h i c h a c o m p l e t e eva lua t i on is made acco rd ing t o ce r ta in rules. T h e cho ice o f t ech n ique f o r eva lua t ion depends o n t h e level o f de ta i l i ng at w h i c h the suggested so lu t i ons are f o r m u l a t e d . These techn iques w i l l n o t be discussed here as there is a great deal o f l i t e ra tu re a l ready pub l i shed o n th is subject .

C o m m o n t o all eva lua t ion s i tua t ions is t he fac t t h a t t he suggested so lu t ions m u s t be m o d e l l e d ( in t he w ides t sense, e.g. in a ske tch o r in a t h ree -d imen sional m o d e l , see Chapter 2 ) , so t h a t one can exam ine the qua l i t ies t o be eva lua ted , such as space, o p e r a t i o n , appearance, etc. T h e var ious suggested so lu t i ons w h i c h mus t be eva luated c o n c u r r e n t l y , mus t necessar i ly be m o d e l l e d w i t h the same degree o f de ta i l , so t h a t a so lu t i on t ha t m i g h t poss ib ly be m o r e t h o r o u g h l y w o r k e d o u t is n o t subconsc ious ly given pre ference over the o thers .

When a series o f suggested so lu t i ons has been evaluated there w i l l usua l ly be more o r mo re so lu t i ons t h a t t u r n o u t t o be be t te r t h a n the o thers . The best one , o r poss ib ly a f e w o f t h e best ones, m u s t be f u r t h e r de ta i l ed , w h i c h gives rise t o a new series o f so lu t i ons at a m o r e de ta i led level . Here again one mus t evaluate and make a cho i ce , b u t th is t i m e accord ing t o o the r (more de ta i led) c r i t e r i a . A f t e r th is , new detai ls are added , and so t h e process con t inues w i t h f u r t h e r so lu t i ons u n t i l all t he detai ls have been dec ided .

4 APPEARANCE OF THE PRODUCT

4.1 T h e idea o f appearance 1 4 3

4 .2 F o r m e lements 1 4 7

4 .3 C o m b i n i n g f o r m e lements 151

4 .4 Means o f expression 1 6 6

141

4. Appearance of the Product

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4.1 The idea of appearance

Aesthetics

The appearance o f a p r o d u c t is a consequence o f t he cho ice o f s t ruc tu re , f o r m , ma te r i a l , d i m e n s i o n and surface ( i nc l ud ing c o l o u r ) , in o the r w o r d s exac t l y t he f ive basic p roper t ies t h a t were discussed in Chapte r 1 .

Appearance can o n l y be evaluated sub jec t i ve l y , as i t can be equated w i t h the visual impress ion given by t he f ive basic p roper t ies . Appearance there

f o re c a n n o t be measured a n d , o f course , i t is th i s f ac t w h i c h gives rise t o m u c h d iscussion w h e n an ob jec t l ooks pleasing.

When des ign ing a p r o d u c t one c a n n o t leave its appearance o u t o f accoun t , b u t t h e degree t o w h i c h th is in f luences t h e f o r m depends o n t he t y p e o f p r o d u c t in q u e s t i o n . F o r ce r ta in p r o d u c t s , appearance is a basic q u a l i t y . Th is appl ies f o r instance t o j ewe l l e r y , c lo thes and f u r n i t u r e . There are also p roduc t s whe re t h e appearance is i m m a t e r i a l , e.g. ca rbu re t t o r s , fe r ru les , nails and screws. A l l o the r p roduc t s are somewhere in be tween these ex t remes , as suggested in t he tab le o n the le f t .

W h a t exac t l y is g o o d appearance, and w h a t is charac ter is t i c f o r a p r o d u c t t h a t we w o u l d cal l beau t i f u l ? U n f o r t u n a t e l y , a sa t i s fac to ry answer has never been f o u n d . T h e nearest one can get is t h a t i t is possible t o i d e n t i f y ce r ta in features t h a t t oge the r give us an idea o f w h y some th ings are ug ly , w h i l e o thers are b e a u t i f u l . Aes the t i cs , i.e. t he s t udy o f b e a u t y , is conce rned w i t h these ques t ions . I t is n o t possible t o d r a w up rules t h a t w i l l ensure a beau t i f u l p r o d u c t , b u t o n t he o the r hand we can give some guide l ines, w h i c h a designer can use w i t h a ce r ta in p r o b a b i l i t y o f a reasonable resul t . T h e rest o f th is chap te r deals w i t h such gu ide l ines.

Specu la t i on o n w h y ce r ta in ar t ic les can give an o n l o o k e r an aesthet ic exper ience has a lways engaged h u m a n i t y . Some peop le have f o u n d beau ty in na tu re , o thers in s t r i c t geomet r i c shapes and o thers again in swe l l i ng curves and garish co lou rs . These peop le m a y all be r i gh t in t he i r o w n w a y . T h e d i f f e rence in taste o f d i f f e r e n t peop le c o u l d o f t e n be t he reason w h y some ar t ic les are f e l t t o be b e a u t i f u l , w h i l e o thers are n o t . However , i f s o m e t h i n g is real ly beau t i f u l mos t peop le can agree. T h e r e f o r e , i t m u s t be possible t o f i n d cer ta in character is t ics t h a t are c o m m o n t o the fee l ing w h i c h gives one an aesthet ic exper ience.

143

144 Appearance of tfie product

Figure 141 An aesthetic product characterised by unity and order (Courtesy Bang & Olufsen)

Beauty m a y in t he f i r s t instance be character ised by its oppos i te - ugl iness. When an ar t ic le is f e l t t o be ug ly i t m a y be because i t is d i sco rdan t , s h o d d y , careless, b i t t y , de fec t ive o r bad ly made. Beau ty is t he c o m p l e m e n t o f ugl iness, and f r o m th is w e m a y get an i n d i c a t i o n o f w h a t beau ty is. One mus t , however , r emember t h a t be tween ugliness and beau ty lies the neut ra l and un in te res t ing . So beau ty m u s t possess o t h e r qua l i t ies apar t f r o m n o t be ing ug l y . T h e m o s t i m p o r t a n t character is t ics are u n i t y and o rder , (see F igure 141 ) .

Unity

A p r o d u c t o u g h t t o appear as a f i n i shed c o m p l e t e u n i t , where the separate e lements and detai ls belong toge the r in a logical and h a r m o n i c w a y . There m u s t be no e lements t h a t s tand o u t as i f t h e y d i d n o t be long , and t h a t arouse quest ions or surpr ise. I t w i l l also be u n f o r t u n a t e i f t he p r o d u c t l ooks as i f some par t is miss ing. I t can be general ly said t h a t any d i s tu rbance o f t he overal l impress ion mars t he appearance.

A h a r m o n i c u n i t m a y be achieved i f t h e c o m p o n e n t e lements are re la ted in some w a y , e.g. by c o m m o n f o r m (basic shapes, curves, e t c . ) , s i m i l a r i t y in sur face s t ruc tu re and in t he cho ice o f co lou rs , (see F igure 1 4 2 ) .

Order

T w o o f t h e qua l i t ies a l ready m e n t i o n e d in connect i o n w i t h ugliness were carelessness and d isorder . I t is t he re fo re na tura l t o exam ine h o w far t he idea o f O r d e r ' belongs t o t h e aesthet ic p r o d u c t . Somet imes o rder in i tsel f m a y sat is fy an aesthet ic need.

T h e h ighest degree o f o rde r - s t r i c t r e p e t i t i o n -w i l l , however , o f t e n become t o o m o n o t o n o u s , w h i l e a f reer and m o r e var ied o rde r can make t h e p r o d u c t an e x c i t i n g sensual exper ience . T h e degree o f o rde r t h a t is mos t su i tab le depends o n t he c o m p l e x i t y o f t he p r o d u c t , in t h e sense t h a t t h e m o r e c o m p l e x t h e p r o d u c t t he h igher a degree o f o rde r is needed. H o w e lements can be arranged w i t h a ce r ta in var ie ty is m o r e c losely e x a m i n e d in sec t ion 4 . 3 . T h e i m p o r t a n c e o f o rder f o r aesthet ic exper ience is i l l us t ra ted in F igure 143 .

145

Figure 142 Unity and iack of unity. Above, a programmable machine tool that constitutes a harmonic unit (courtesy Vilh. Pedersens Machine Factory Ltd.). Below, a car where the superstructure and the chassis do not seem to belong together

146

Figure 143 Order and disorder. Above, an offset writing machine where the separate form elements express order in respect of both form and arrangement. (Courtesy of Helioprint Ltd). Below, a typical prototype that bears the stamp of disorder. In this case one does not worry about appearance

but about function

4.2 Form elements

Appearance of tfie product 147

Mos t i ndus t r i a l l y m a n u f a c t u r e d p roduc t s are b u i l t up o f a n u m b e r o f e lements o f a re la t ive ly s imp le geomet r ica l f o r m . In t he m o r e c o m p l e x p roduc ts and machines t he e lements are p u t t oge the r i n t o subsystems, w h i c h again are o f t e n in t he f o r m o f k n o w n geomet r ica l shapes.

The p r o d u c t is t he re fo re usual ly character ised by a n u m b e r o f ' f o r m e lements ' , w h i c h t oge the r make up t he o u t e r f o r m . These f o r m e lements he lp t o give the p r o d u c t its character , w h e t h e r th is f ac t has been taken de l ibera te advantage o f o r n o t .

T h e f o r m e lements t h a t are me t mos t o f t e n are the basic shapes o f t he cube — t h e c y l i n d e r , t h e sphere, t he p y r a m i d , t h e cone and t h e e l l ipso id or parts o f these, see F igure 144 . T h e b o x and t h e c y l i n d e r are the f o r m e lements mos t o f t e n used, w i t h the resul t t h a t t h e m a j o r i t y o f p roduc t s consis t o f l ines and planes at r i gh t angles t o each o the r . Several reasons f o r th is s i t ua t i on m a y be m e n t i o n e d :

The M i n d . ' The eye ' is na tu ra l l y used - to perce iv ing ver t ica l and h o r i z o n t a l as

t h e m a i n visual d i r ec t i ons , and i t is na tu ra l t o t h i n k in t e rms o f these d i rec t i ons .

Models . When i t is necessary t o s u p p l e m e n t t he i m a g i n a t i o n th is m a y be done by using a m o d e l . By far t he mos t w i d e l y used t y p e o f m o d e l is a d r a w i n g , mos t o f t e n in r ight -ang led p r o j e c t i o n . In th is sor t o f p ro j e c t i o n m u c h the easiest ob jects t o ske tch are those t h a t b r o a d l y consis t o f planes paral le l t o t h e p r o j e c t i o n planes.

Techno log ies . M a n u f a c t u r i n g processes f avou r ob jec ts w i t h planes at r i gh t angles t o each o t h e r and those t h a t can be t u r n e d o n a la the.

The above c o m m e n t s mus t n o t be regarded as a rgumen ts f o r t h e f o r m e lements a lways hav ing t o be s imp le geomet r i ca l f o r m s , f o r na tu ra l l y the designer has a lways his f r e e d o m inside t he l im i t s o f t he

BASIC SHAPES O o /7\

PARTS OF BASIC SHAPES

Figure 144 Form elements

148 Appearance of the product

used as means o f ge t t i ng ideas, b o t h w h e n w o r k i n g on t he t o t a l f o r m and w h e n dec id ing o n t h e f o r m o f t h e e lements (as descr ibed in sec t ion 2 . 3 ) . I t is, however , n o t enough t o mere l y emphasise the i m po r tance o f t he idea o f f o r m e lements . T h e designer m u s t k n o w t h a t t h e co r rec t i n t eg ra t i on o f t h e f o r m e lements is essential t o the appearance o f t he p r o d u c t . T h e f o l l o w i n g sec t i on , t h e r e f o r e , shows w h a t happens w h e n several f o r m e lements are p u t toge the r , and w h a t can be d o n e t o achieve a harm o n i o u s resul t .

Figure 145 A number of smaller components in which the form elements from Figure 144 can be

recognised

c r i t e r i a . However , i f a n u m b e r o f p roduc ts are s tud ied on t h e basis o f t h e f o r m e lements t h e y consists o f , i t w i l l be f o u n d t h a t t he basic shapes in F igure 1 4 4 have been used. F igure 145 shows th is f o r a n u m b e r o f smal l c o m p o n e n t s . In the m o r e c o m p l e x p roduc t s s h o w n in Figures 146 t o 149 t he basic shapes are used in t h e f o r m design o f t he smal lest e lements u p t o the c o n s t r u c t i o n o f t he t o t a l sys tem.

T h i n k i n g in t e rms o f f o r m e lements is i m p o r t a n t t o the designer, because t h e basic shapes can be

149

Figure 146 Fresh water plant. Note the clearly defined fornn elements both in the total form and in the details (Courtesy

of Atlas Ltd)

Figure 147 An automatic lathe with many form elements (Courtesy of Boehringer)

150

Figure 148 l\nicroscope built up of simple geometric basic forms (Courtesy of Carl Zeiss)

Figure 149 Excavator built up of pronounced form elements (Courtesy of J. C. Bamford Exc.)


4.3 Combining f o r m elements

Visual balance

Le t us examine t w o iso la ted f o r m un i ts or f o r m e lements and t r y t o c o m b i n e t h e m . I f t he f o r m e lements are m o v e d t o w a r d s each o t h e r we no t i ce t ha t , a t a cer ta in d is tance, t h e y seem t o be long t o gether and have f o r m e d a g r o u p (see F igure 150 (a) and (b ) ) . T h e idea o f g r o u p is f u n d a m e n t a l t o o u r visual pe r cep t i on . I f we s t u d y a n u m b e r o f e lements in a g r o u p t h e y w i l l a f fec t each o the r , apar t f r o m jus t seeming t o be long toge the r . We w i l l feel t h a t the e lements are v isua l ly m o r e o r less in balance.

A visual balance m a y be achieved by s y m m e t r y , or i t m a y be asymmet r i ca l . In t h e la t te r case the c o m p o n e n t e lements mus t be shaped and ar ranged in re la t i on t o each o t h e r in such a w a y t h a t the re seems t o be the same ' w e i g h t ' (a c o m b i n a t i o n o f f o r m and c o l o u r ) o n b o t h sides o f an imag ina ry

cen t ra l l ine . V isua l balance is i l l us t ra ted in F igure 150 (c) t o (e) , whe re (c) shows i t achieved b y s y m m e t r y , (d) an asymmet r i ca l balance and (e) a visual imba lance .

I f a g r o u p o f f o r m e lements are n o t in balance t h e y m a y ' o f f e n d the eye ' . One m u s t especia l ly guard against cases whe re t h e t o t a l f o r m is very near ly s y m m e t r i c a l , b u t n o t q u i t e . A g o o d rule o f t h u m b is, t h a t t he f o r m m u s t be e i the r s y m m e t r i c a l o r s u f f i c i e n t l y asymmet r i ca l f o r i t t o be c lear ly de l ibera te a n d n o t s i m p l y lopsidedness.

Figures 151 and 152 s h o w examples o f visual balance on the f r o n t o f t w o meters . F igure 153 shows a v a c u u m p u m p in visual imba lance ( i t l ooks as i f i t w i l l t o p p l e o v e r ) , a n d F igure 154 a v isua l ly ba lanced ver t ica l d r i l l .

Figure 150 The group effect between two elements (a and b), visual balance (c, symmetrical; d, asymmetrical) and visual imbalance (e)

152

Figure 151 Visual balance through symmetry (Courtesy of Bruel & Kjaer)

Figure 152 Visual balance without symmetry (Coutesy of DISA Electronic Ltd.)

153

Figure 153 Vacuum pump which gives an impression of visual imbalance

Figure 154 Vertical drill in visual balance


Rfiytfim

In t he sect ion o f aesthet ics (page 143) i t was m e n t i o n e d t h a t one i m p o r t a n t charac ter is t ic o f beau t i f u l p roduc t s is o rder . A t t he same t i m e i t was emphasised t h a t t he degree o f necessary o rde r depends o n t he degree o f c o m p l e x i t y . T h e idea o f o rder is thus m o s t p r o n o u n c e d w h e n m a n y e lements are present .

Le t us cons ider a great n u m b e r o f s imi la r e lements as s h o w n in F igure 155a . T h e a r rangement where t h e y are equa l l y spaced represents t he h ighest degree o f o rder , b u t p u t t oge the r in th is w a y t h e e lements

c o n s t i t u t e an un in te res t i ng r o w . H o w can w e make t he g r o u p o f e lements m o r e exc i t i ng? We can i n t r o duce a ce r ta in va r i a t i on w h i c h we repeat w i t h su i tab le in tervals . Th is ' o rde r w i t h v a r i a t i o n ' o r ' R h y t h m ' m a y be car r ied o u t b y using t h e va r i a t i on parameters f r o m sec t ion 2 .3 . These are a r rangemen t , d i m e n s i o n , n u m b e r and f o r m o f e lements ( th is in c ludes t he i r c o l o u r ) . F igure 1 5 5 b shows t h e e lements in groups whe re r h y t h m is i n t r o d u c e d in d i f f e r e n t ways .

b NUMBER

ARRANGEMENTS φ ® © © ® ® ® ® ©

DIMENSION O ^ ©

® ^

SHAPE AND COLOUR

© ^ * 0 O Q O © Q O O ^ O O ^ ©

ο ® ο · ο © ο · ο ® ο · ο ο ο

Figure 155 Rhythm through variation of arrangement, dimension, number and form of the elements

Appearance of the product 155

Figure 156 A ship's transmitter. The rhythm is achieved by varying the arrangement and the dimensions of the deals; alternating between rectangular and round elements and

making the module heights different

T h e e x t e n t t o w h i c h rhy thnn is i n t r o d u c e d i n t o a R h y t h m based o n v a r y i n g t h e f o r m o f t h e e lements g roup o f e lements depends, as a l ready m e n t i o n e d , can also be a p o w e r f u l t o o l . In t h e cars s h o w n in n o t o n l y o n t he c o m p l e x i t y ( n u m b e r and d i ss im i l a r i t y F igure 157 t he shape o f w i n d o w s and doors is em-o f t h e e lements) b u t also o n personal taste. F igure phasised by t h e sys tem o f l ines w h i c h t h e y f o r m . T h e 156 shows a design o f a ship 's t r a n s m i t t e r whe re a r rangement , shape and angle o f t h e l ines toge the r r h y t h m helps t o make t h e appearance e x c i t i n g , f o r m a r h y t h m , t h a t has a d i f f e r e n t charac te r f o r t h e R h y t h m has been achieved by va ry i ng the arrange- d i f f e r e n t cars, m e n t and t h e d imens ions .

156

Figure 157 Three cars where the prominent lines give different rhythms

Proportions


T h e idea o f u n i t y , m e n t i o n e d in the sec t ion o n aesthet ics is an i m p o r t a n t í/íya/zY/. T h e f o r m e lements mus t be su i ted t o each o t h e r in a logical and harm o n i o u s w a y , and c o m m o n features in t he i r sur face, s t ruc tu re and c o l o u r are t he re fo re necessary. One o f the parameters t h a t can he lp t o unde r l i ne t he overal l impress ion is t he p r o p o r t i o n .

Man has a lways been p reoccup ied w i t h the idea o f a c o n n e c t i o n be tween p r o p o r t i o n and beau ty . There are examples o f ideal measurements f o r beau t i f u l h u m a n beings, and f o r instance, t he G o l d e n Sec t i on , w h i c h is a m a t h e m a t i c a l l y d e t e r m i n e d ra t i o be tween t w o l ines A and B, de f i ned by

A

Β

Β

A rectangle w i t h th is ra t i o be tween its sides is charac ter ised by be ing d iv is ib le i n t o a square and a n o t h e r rectangle w i t h t he same ra t i o be tween its sides, see F igure 158 . T h r o u g h o u t t h e ages m a n y peop le have cons idered th is rectangle t o be perfect i o n .

Rat ios such as 2 : 3 , 3 : 5 , 5 : 8 , 8 : 1 3 etc are even c loser a p p r o x i m a t i o n s t o the G o l d e n Sec t i on . These p r o p o r t i o n s are app l i ed in a great m a n y areas. F o r instance, t e x t b o o k s o n p h o t o g r a p h y teach the adv isab i l i t y o f p lac ing t he m o s t i m p o r t a n t par t o f t h e p i c t u re in such a w a y t h a t i t d iv ides t he sides in t h e ra t i o 2 : 3 o r 3 : 5 . These p r o p o r t i o n s m a y be recognised in m a n y p r o d u c t s .

A - B .

Th is gives: Í2=i /2( i + / 5 ) - 1 . 6 1 8 . Β

Figure 158 Above, division of a line by the Golden Section. Below, a rectangle in proportions corresponding to the Golden Section

1 5 8 Appearance of tfie product

i sa t i on , and also f l e x i b i l i t y , b u t a d iscussion o f these is ou ts ide t h e scope o f t h e b o o k . Us ing modu les t o d i v ide an area i n t o sect ions, e.g. o n c o n t r o l panels, is a conven ien t w a y o f f i t t i n g e lements o f d i f f e r e n t sizes as a w h o l e .

F igure 160 shows a haemod ia lys is appara tus , i.e. a c o n t r o l u n i t used in c o n j u n c t i o n w i t h an a r t i f i c ia l k i d n e y f o r t rea t i ng pa t ien ts w i t h c h r o n i c k i d n e y c o m p l a i n t s . Dia ls , c o n t r o l lamps, e tc are g r o u p e d in sect ions c rea ted b y d i v i d i ng t h e o u t e r area i n t o 3 , respect ive ly 5 , par ts . T h e modu les o f he igh t a n d w i d t h are in t h e r a t i o o f 5 : 3 .

Figure 159 Division of the surface of a record player. The division contains rectangles and two squares (Courtesy of Bang & Olufsen)

Repeated use o f ce r ta in p r o p o r t i o n s in t he elements o f a p r o d u c t m a y , a m o n g o the r th ings , resul t in t he appearance o f s imi lar e lements . Th is may also c o n t r i b u t e great ly t o t he p r o d u c t appear ing as a h a r m o n i o u s u n i t . F igure 159 shows a g r a m o p h o n e , whe re there are f o u r s imi la r rectangles a n d t w o squares.

A conven ien t a id t o d e t e r m i n i n g t he p r o p o r t i o n s is t he use o f modu les , t he basic size o r a basic area, w h i c h in var ious ways can be assembled i n t o larger e lements . Modu les can na tu ra l l y have m a n y o t h e r advantages such as reduc ing costs t h r o u g h s tandard

159

Figure 160 Use of modules in dividing up tfie front of a haemodialysis apparatus (Courtesy of the Institute of Product Development, The Technical University of

Denmark)

160 Appearance of the product

Lines and planes

Occas iona l l y , w h e n f o r m e lements are p u t t oge the r u n e x p e c t e d visual ef fects w i l l arise. T h e visual impress ion o b t a i n e d w h e n l o o k i n g at a u n i t is n o t jus t t h e sum o f t he impressions f r o m the e lements . These in f l uence each o t h e r v isua l ly . T h e visual e f fec t is t he reason w h y one mus t pay a t t e n t i o n t o t he lines and planes in a p r o d u c t , so t h a t a f o r m design can be c reated where these are in re la t i on t o each o the r .

T h e qua l i t ies o f u n i t y and o rde r depend o n t h e r u n o f t he l ines and planes. One t he re fo re usua l ly t r ies t o give the p r o m i n e n t l ines in t h e p r o d u c t t he same charac ter , e.g. s t ra igh t l ines, curves and l ines at a ce r ta in angle, see Figures 161 a n d 162 .

C o n t i n u i t y in t he run o f t h e i nd i v i dua l l ines is also s ign i f i can t . F igure 163 shows examples o f t h e w a y in w h i c h a d i s c o n t i n u o u s r u n o f l ines a t t rac ts a t t e n t i o n u n f a v o u r a b l y .

Figure 161 Pumps and scales marked by, respectively, curved and flat planes (Courtesy of DAE Pumps Ltd and Rex Scales Factory Ltd)

161

Figure 162 A perfusator (a box for preserving and transporting living kidneys before a transplant). In the form are found a number of similarly inclined lines (Courtesy of the Lab. of Engineering Design, The Technical University of Denmark)

162

Figure 163 Examples of lines which attract unfavourable attention

Appearance of the product 163

Joints

Jo in ts be tween f o r m e lements can give rise t o b o t h cons t ruc t i ona l and visual p rob lems . I f t w o planes or edges meet t i g h t l y w i t h an uncovered d i v i d i n g l ine i t w i l l o f t e n d e m a n d unreasonable e x a c t i t u d e and para l le l i sm. I t is, t h e r e f o r e , w o r t h n o t i n g t h a t f r o m a visual p o i n t o f v iew one can a d o p t t w o a t t i t udes t o j o i n t s :

1 . The e lements are so designed t h a t the j o i n t on the w h o l e i sunno t i ced , t h a t is t o say t h a t t he dem a n d f o r exac t i t ude is accepted o r t h a t t h e j o i n t is h i dden , e.g. by pa in t .

2. T h e j o i n t is emphasised and de l ibe ra te ly used as pa r t o f t h e f o r m character is t ics o f t h e p r o d u c t . There are several m e t h o d s w h i c h can be used t o achieve th is — d is tance be tween the e lements — g roov ing - s ta in ing t h e groove da rk - cove r ing the j o i n t w i t h a m o u l d i n g o r s o m e t h i n g s imi lar .

F igures 164 t o 167 s h o w d i f f e r e n t examples o f ways o f so lv ing t he p r o b l e m o f j o i n t s .

Figure 164 Different possibilities for joining two elements end-on

Figure 165 Different possibilities for joining two elements at right angles

Figure 166 Examples of joints. (See also Figures 164 and 165)

165

Figure 167 Examples of joints. (See also Figures 164 and 165)


4.4 Means of expression

Lightness

Based o n associat ions w h e n l o o k i n g at t he f o r m there are cer ta in qua l i t ies w h i c h are expec ted in a p r o d u c t . In o the r w o r d s , i t is fe l t t h a t t he f o r m can express some th ing . Th is fac t m a y be c o n sc ious ly used by t h e designer, e i ther t o emphasise cer ta in o f t h e p r o d u c t ' s character is t ics o r t o m i t i gate possible undes i rab le ones.

One q u a l i t y t h a t can be stressed t h r o u g h the f o r m is l ightness. F igure 168 shows t w o s i tua t ions whe re an ob jec t seems t o have been made l igh ter .

In t h e f i r s t examp le , t h e l o w e r p a r t o f t h e ob jec t has been shaped as a p l i n t h o r legs, w h i c h gives the impress ion t h a t t he ob jec t does n o t rest so heav i ly o n the f o u n d a t i o n . T h e o t h e r examp le is a p r o j e c t i n g pa r t w h i c h can be made l igh te r by s lop ing t he b o t t o m l ine u p w a r d s .

Figures 1 6 9 a n d 170 s h o w h o w the d i a g r a m m a t i c examples in F igure 168 can be app l i ed in designing p r o d u c t s .

W/////// /}//////hr /y>////y/. 7* \jyy//^/7

//} / ///7f7

Figure 168 Two situations where the object appears to have been made lighter

167

Figure 169 Products where the form expresses lightness (see also Figure 168). The objects shown are: top left, a vibration meter. (Courtesy of Bruel and Kjaer); top right, a teamaker. (Courtesy of Lab. for Engineering Design, The Technical

University of Denmark). Below, a workbench. (Courtesy of Brown and Sharpe)

168

Figure 170 Further products where the form expresses lightness (see also Figure 168). The objects shown are: top left, a photocopier. (Courtesy of Eskofot Ltd); middle and bottom left, front of car and side view of car front (Courtesy of Sunbeam and Opel); middle right, a TV set (Courtesy of Bang and Olufsen); bottom right, an operating console (Courtesy

of Digital Equipment Corp.)


Weight and stability

The means t h a t can be used t o express we igh t and s tab i l i t y t h r o u g h the f o r m , a im at p lac ing the cen t re o f g rav i ty l o w d o w n . Fo r th is purpose s lop ing l ines o r ' heavy ' curves are usefu l . I t is a f ac t , as far as s lop ing l ines are conce rned , t h a t a single l ine expresses i ns tab i l i t y , w h i l e t w o lines leaning t o w a r d s each o t h e r express a h igh degree o f s t ab i l i t y , as s h o w n in F igure 171a. F igure 171b demons t ra tes h o w bodies w i t h s l igh t l y concave sides are heavy c o m p a r e d t o bodies w i t h convex sides. F igure 171c

shows examples o f ways in w h i c h these t w o ef fects can be used t o accen tua te t h e s tab i l i t y o f a box -shaped b o d y . In some o f t h e suggest ions the f o r m is d i v i ded i n t o t w o f o r m e lements , w h i c h at t he same t i m e gives greater f r e e d o m in choos ing p r o p o r t i o n s .

P roduc ts , w h i c h as a resul t o f t he i r f u n c t i o n are heavy a n d so l i d , can be shaped so t h a t th is is expressed in t h e f o r m . F igure 1 7 2 shows some mach ines t h a t convey s tab i l i t y and s t reng th .

////////// //////////////

Figure 171 l\/leans of expressing weight and stability

170

Figure 172 Products designed in a way tfiat accentuates weight and stability, left, two fork lift trucks. (Courtesy of Crown); top right, a lathe (Courtesy of Drehbank, Colchester); bottom right, an excavator (Courtesy of J. C. Bamford

Excavators Ltd)

Movement


A n impress ion o f m o v e m e n t and speed can , l i ke s t ab i l i t y , be achieved by using s lop ing l ines, a l t h o u g h in ano the r w a y . T w o lines t h a t meet in a p o i n t give associat ions w i t h an a r r o w , p rov ided t h a t t he angle be tween t h e m is n o t t o o great. I t is t he re fo re possible t o let t he f o r m under l i ne m o v e m e n t by using

s lop ing or s l i gh t l y cu rved l ines at a re la t i ve ly s l ight angle t o t he d i r e c t i o n o f m o v e m e n t , see F igure 173 . T h e m o v e m e n t m a y be f u r t h e r emphasised by accen t ing l ines in the d i r e c t i o n o f m o v e m e n t , as w e k n o w f r o m 'speed s t r ipes ' on w h i c h are pa in ted o n some cars and ra i lway carr iages, e tc .

Figure 173 Products designed in way tfiat emphasises speed

5 CASE HISTORY: CHROMOSOME APPARATUS

5.1 Introduction to the project 175

5.2 Basic structure 179

5.3 Quantified structure 182

5.4 Form of the total system 186

5.5 Form of the elements 196

173

5. Case History: Chromosome Apparatus

ProUem

and means

3 1

m Basic striActure

Total Jorm

Element

5.1 In t roduct ion t o the project

In t h e prev ious chapters w e have at tennpted t o establ ish a systennatic app roach a n d an organised sys tem b y w h i c h i t s h o u l d be possible t o go t h r o u g h the f o r m design stages o f a p ro jec t . T h e examples , by and large, have been t a k e n o u t o f t he se t t ing in w h i c h t h e y have — o r m i g h t have — be longed . Fo r th i s reason i t has n o t been possib le t o give a m o r e de ta i l ed p i c t u r e o f t h e e x t e n t t o w h i c h i t is possible t o a p p l y t h e sys temat i c m e t h o d s in a design p ro jec t .

I t is obv ious l y unrea l is t ic t o w o r k sys temat i ca l l y t h r o u g h all t he e lements in a c o m p l e x p ro jec t . B u t i f one has absorbed t he sys temat ic m e t h o d s there is a basis f o r an a t t i t u d e t o t he w o r k o f designing w h i c h , i n a g iven s i t u a t i o n , results in a m o r e o r less consc ious a p p l i c a t i o n o f t h e sys tem u p t o a ce r ta in manageable stage, w h i l e f o r especial ly d i f f i c u l t o r c r i t i ca l elements one uses t he t h o r o u g h sys temat ic p rocedure .

By m o r e c lose ly f o l l o w i n g the f o r m design stages in a single design p r o j e c t i t s h o u l d be possible t o observe, h o w in d i f f e r e n t s i tua t ions one changes be tween sys temat i ca l l y d r a w n u p series o f so lu t i ons and a m o r e f ree and re laxed w a y o f w o r k i n g w i t h f o r m design ideas. T h e p ro j ec t , w h i c h is descr ibed b e l o w , is t he design o f an apparatus f o r c h r o m o s o m e analysis. T o enable th i s case h i s t o r y t o be seen in t he r i gh t perspect ive t he tab le o n t he le f t shows w h i c h parts o f t h e c o m p l e t e p ro j ec t are be ing s tud ied .

C h r o m o s o m e s ca r ry o u r i nhe r i t ed character is t ics . In each cel l in t h e h u m a n b o d y is a c o m p l e t e col lect i o n o f these. T h e y are f o u n d in t he so-cal led genes, w h i c h n o r m a l l y ex is t in a cell nucleus separate f r o m the rest o f t h e ce l l . W h e n t h e cel l d iv ides, w h i c h o f course is a c o n d i t i o n f o r any g r o w t h and l i fe , t he

175

176 Case history: chromosome apparatus

I

11 I

Figure 174 Miscoscope pictures of chromosomes in a cell

genes gather i n t o l ong threads t h a t n o w f i l l t he w h o l e ce l l . These threads are w h a t w e cal l c h r o m o s o m e s . In a m ic roscope the c h r o m o s o m e s m a y l o o k as s h o w n in F igure 174 . When the cel l d i v i s ion is c o m p l e t e d the c h r o m o s o m e s d iv ide leng thwise , w h e r e b y t h e new cell nuc le i are c rea ted , t h a t f o r m t h e basis f o r t w o new cells.

N o r m a l h u m a n beings have 4 6 c h r o m o s o m e s , b u t t he re m a y be abno rma l c h r o m o s o m e c o m b i n a t i o n s , w h i c h resul t in var ious diseases. In cases where s o m e b o d y ' s c h r o m o s o m e s are e x a m i n e d a c h r o m o some analysis is car r ied o u t , w h i c h produces a so-cal led k a r y o t y p e d iag ram, whe re p ic tu res o f the i nd i v idua l c h r o m o s o m e s are ar ranged sys temat i ca l l y , see F igure 175 .

C h r o m o s o m e analysis is used in var ious s i tua t i ons , i n c l u d i n g diagnosis and e x a m i n a t i o n o f e m b r y o n i c f l u i d as we l l as research. T h e reason w h y c h r o m o some analysis can be used in diagnosis is t h a t there is a c o n n e c t i o n be tween cer ta in diseases (e.g. m o n g o l i s m ) and the c h r o m o s o m e c o m p o s i t i o n o f t he pa t ien ts . E x a m i n a t i o n o f e m b r y o n i c f l u i d is u n d e r t a k e n i f there is a susp ic ion t h a t an e m b r y o m a y have an abno rma l c h r o m o s o m e c o m p o s i t i o n .

In a sl ide p repared f r o m the e m b r y o n i c f l u i d one can observe the c h r o m o s o m e c o m p o s i t i o n and so

1 2 3 ii π 4 5

II If II Ir II nil I 6 7 8 9 10 11 12 X

Μ II II II Η 13 14 IS 1β 17 18

Μ t i 19 20

t i ti 21 22 Y Figure 175

Karyotype diagram

Case history, chromosome apparatus 177

ascertain w h e t h e r th i s is no rma l or i f t he re is somet h i n g w r o n g . E x a m i n a t i o n o f parents- to-be is made i f there is a p r o b a b i l i t y t h a t a c h i l d m a y be b o r n w i t h a c h r o m o s o m e a b n o r m a l i t y . F r o m such an e x a m i n a t i o n one can es t imate h o w great th is p r o b a b i l i t y is. C h r o m o s o m e analysis is used in research examine w h e t h e r diseases w i t h so fa r u n k n o w n causes m a y be due t o c h r o m o s o m e a b n o r m a l i t y . A c h r o m o s o m e analysis compr ises the f o l l o w i n g stages: t h e e x t r a c t i o n o f su i tab le cel ls, p repa ra t i on o f the ce l l , s ta in ing ( t o make t he c h r o m o s o m e s m o r e d i s t i nc t ) and an actua l analysis, in w h i c h t he k a r y o t y p e is made.

O n l y t h e actual analysis w i l l be discussed here. T h e s ta r t ing p o i n t is a prepared s l ide, w h i c h is p u t i n t o a m ic roscope . T h e sl ide con ta ins several cel ls, and i t is t he f i r s t j o b o f t he l a b o r a t o r y assistant t o f i n d a su i tab le cel l ( i .e. one w i t h d i s t i n c t c h r o m o somes t h a t d o n o t ove r lap ) . When a cell has been f o u n d a p h o t o g r a p h is t a k e n . F o r sa fe ty , one usua l ly takes one m o r e p h o t o g r a p h o f a n o t h e r su i tab le ce l l . Later , w h e n the l abo ra to r y assistant gets t h e p h o t o graphs back f r o m deve lopmen t , t h e k a r y o t y p e can be prepared. Th is is done by c u t t i n g o u t , ar rang ing

and g lue ing o n t o a s tandard d iag ram all t h e c h r o m o somes. A f t e r t h a t t h e k a r y o t y p e is ready , and an ac tua l assessment o f t h e c h r o m o s o m e c o m p o s i t i o n can be made . The p rocedure in t h e manua l process here descr ibed is i l l us t ra ted in F igure 176 .

In assessing t h e poss ib i l i t ies o f m a k i n g t he c h r o m o some analysis a u t o m a t i c , one w i l l realise t h a t th is m a y be done at m a n y levels. In m a n y places, f o r ins tance, peop le are deve lop ing a sys tem t h a t au to m a t i c a l l y carr ies o u t all t h e par t ia l processes, f r o m seek ing o u t a su i tab le cel l u p t o t h e f i n i s h e d k a r y o t y p e o r s imi la r c o m p u t e r ma te r i a l . Even i f such systems m a y t echn i ca l l y f u n c t i o n t h e y have a n u m b e r o f d rawbacks . F o r one t h i n g , t h e y requ i re t h a t a c o m p u t e r is avai lable, also t h a t an ope ra to r is present , w h o - depend ing o n t h e sys tem - m u s t ca r r y o u t var ious assessments f o r t h e process t o be possib le.

T h e basis f o r t h e present p ro j ec t was t h a t i t was cons idered p robab le t h a t a s o l u t i o n w i t h a smal ler degree o f a u t o m a t i o n w o u l d be m o r e advantageous t h a n e i the r t he manua l or t h e f u l l y a u t o m a t i c process. So t h e basic idea f o r t he p ro jec t became t o design an appara tus w h i c h by i tse l f can

- SUde

j Kiicroscope

Photogrfipk

£7 ¿7 a Ρ17 a cr L7 an ¿y ^

k(^roti)pe

Figure 176 The manual process in mal<ing Karyotypes


SUcLe Ckromosome kar

Figure 177 The chromosome apparatus as a black box

ca r ry o u t t he opera t ions t h a t the l a b o r a t o r y assistant had prev ious ly per fornned, b u t w h i c h makes use o f his a b i l i t y t o i d e n t i f y t h e c h r o m o s o m e s . In th is w a y i t becomes possible t o p e r f o r m the c h r o m o some analyses in cons iderab ly shor te r t i m e , as we l l as t o make t he apparatus cheaper, because t h e c o m p l i ca ted opera t ions - t o seek o u t and recognise t he ch romosomes - are p e r f o r m e d by t h e o p e r a t o r , w h i l e the t r i v i a l , t r o u b l e s o m e and t i m e c o n s u m i n g m o r e mechan ica l opera t ions are car r ied o u t in t h e apparatus . A f u r t h e r advantage over t h e manua l m e t h o d is t h e fac t t h a t t h e k a r y o t y p e is o b t a i n e d w h i l e t h e sl ide is in t h e m ic roscope in t he p o s i t i o n whe re t h e cel l i n ques t i on is s h o w n . Th is makes i t possible t o compare t h e k a r y o t y p e w i t h t he cell p i c tu re in any cases o f d o u b t . T h e task can n o w be f o r m u l a t e d in m o r e de ta i l .

We w a n t t o design a sys tem w h i c h , b y using h u m a n a b i l i t y t o recognise pa t te rns , makes possible an increase o f t he analysis capac i t y o f a c h r o m o some l a b o r a t o r y . T h e o u t p u t f r o m the analyses mus t

be a k a r y o t y p e d iagram p r i n t e d o n du rab le mate r ia l su i tab le f o r arch ive storage.

H o w t h e process in F igure 177 can be sp l i t i n t o par t ia l processes w i l l n o t be f u r t h e r discussed here. T h e d iv is ion m a y be made in m a n y ways , and F igure 178 shows the p re fe r red p rocedu re . I t w i l l be seen f r o m t h e f i gu re t h a t i t has been c lear ly dec ided w h i c h par t ia l processes t h e o p e r a t o r a n d t h e apparatus each w i l l p e r f o r m .

T h e m a i n f u n c t i o n s t h a t t he c h r o m o s o m e apparatus m u s t ca r r y o u t m a y be seen in F igure 178 . These are t o create a visual p i c t u r e , t o d e l i m i t t he pa r t i cu la r pa r t o f t he s l ide, t o o r i en ta te i t , t o c lassi fy i t ( in t he k a r y o t y p e ) , a n d t o expose i t . I t has been dec ided t o p e r f o r m t h e f u n c t i o n o f c rea t ing a visual p i c t u r e w i t h a t r a d i t i o n a l m i c roscope , and t h e f u n c t i o n o f expos ing as in an o r d i n a r y camera w i t h a shu t te r . T h e th ree cent ra l m a i n f u n c t i o n s r e m a i n : d e l i m i t a t i o n , o r i e n t a t i o n a n d c lass i f i ca t ion o f t h e sl ide pa r t . In t h e n e x t sec t ion these th ree f u n c t i o n s are t a k e n as s ta r t i ng po in t s f o r t h e search f o r basic s t ruc tu res .

APPA/^ATUS ΟΡΕΙ^ΑΎΟΙ^

Mark in store

SUde Create Visual pUtiAre

picture

5e*k and recognise cMrom.

In/or on wkctke^r used

Infor on. cLassLJLcation

feed in pas and orientation Inf or. on pos

and orientation

Information on ex pos are

FUm

APPAKAIUS

DeCimit slide part

Orientate slide part

Classify slide part

Expose

Figure 178 Chart showing the main functions which must be carried out by the chromosome apparatus

DeUkKit ckosen ckrom.Jirom total muroscope p/ct.

CUsslJ^ chrotn.

QDQ BD α α α q a a

Case history: chromosome apparatus 179

5.2 Basic structure

T h e th ree f u n c t i o n s t h a t fornn t h e basis f o r devis ing basic s t ruc tu res are i l l us t ra ted In the tab le o n t h e le f t . T h e nneans t h a t can realise these are s h o w n in F igure 179 . I t is assumed t h a t op t i ca l o r o p t i c a l / p h o t o g r a p h i c so lu t ions are used, and n o t f o r instance e lec t ron i c ones (see page 1 8 2 ) . T h e m e t h o d s in F igure 1 7 9 are s h o w n a t a re la t i ve ly abst rac t level , w h i c h keeps t h e poss ib i l i t ies d o w n t o a reasonable n u m b e r . T h e n e x t step w i l l n o w be t o c o m b i n e th ree f u n c t i o n s i n t o d i f f e r e n t basic s t ruc tu res . A great n u m b e r o f c o m b i n a t i o n s are t h e o r e t i c a l l y possib le, b u t m a n y o f t he so lu t i ons are c o m p l i c a t e d , and several have o t h e r obv ious d rawbacks c o m p a r e d t o o t h e r so lu t i ons . These m a y be re jected s t ra igh t away . In o rde r t o progress i t is necessary t o deta i l t h e so lu t i ons f u r t h e r . Th i s is done by e x a m i n i n g h o w a penc i l o f l i g h t can be m o v e d , as s h o w n in F igure 180 , and also h o w i t can be t u r n e d , w h a t mechan ica l m o v e m e n t s are necessary, etc. T h e m a n y possib i l i t ies can o n l y be assessed a f te r var ious ca lcu la t ions and e x p e r i m e n t s , and t he c r i t e r i a w h i c h comes i n t o t h e p i c t u r e at th i s stage are, p i c t u re qua l i t y , space requ i remen ts , mechan ica l c o m p l e x i t i e s , special cos t c i r cumstances , t i m e t a k e n , etc. T h e f ina l cho i ce is o n l y made a f t e r a n u m b e r o f basic s t ruc tu res have been d r a w n u p .

OKIEkllAlE

I CLASSIFY

K1

01

>̂ 3 \PAPEI^lFim 1

paper MampuLeite cut out part picture

03 ¡PAPflC/F/LU ]

KJew ptciure

\papei^Jfilm]

PnnUnj

Figure 179 Means of realising tfie functions of delimitation, orientation and classification


d e l i m i t a t i o n w i t h t he aid o f a s l id ing lens, and classi f i c a t i o n by means o f a t i l t i n g m i r r o r . O r i e n t a t i o n is p e r f o r m e d b y Abbe ' s p r i s m .

One i m p o r t a n t par t o f t h e basic s t r uc tu re has n o t y e t been m e n t i o n e d , name ly t h e pa r t w h i c h involves the ope ra to r . A m o n g a n u m b e r o f poss ib i l i t ies i t has been dec ided t h a t t he o p e r a t o r w i l l have a p i c t u re o f the sl ide on a screen in f r o n t o f h i m . T h e i n p u t t o t h e apparatus w i l l t ake place in such a w a y t h a t i n f o r m a t i o n o n d e l i m i t a t i o n and o r i e n t a t i o n is given t h r o u g h a mechan ica l v i e w f i n d e r , w h i c h t h e ope ra to r po in t s at t he desi red c h r o m o s o m e , w h i l e i n f o r m a t i o n on - the c lass i f i ca t ion is passed t h r o u g h a k e y b o a r d .

Ύ77Ζ777

M//^J^0KS

1 2co-ord 2co-ord

-T7777? 2 CO-Ord

Λ

////

LENSES

2co-ord P/^/SUS

2 co-ord 2 co-ord

^r9rr -iTTzr -rrrrr 7 7 7 ^ TTTTT τττττζτ 2 CO-ord 2CO-ord

FIBKB OPT/CS

2 co-ord

Figure 180 /\/leans of realising the function of "moving" a ray of light

F r o m ou r know ledge o f the par t ia l so lu t ions in F igure 180 t he n u m b e r o f basic s t ruc tures m a y be reduced t o f o u r t e e n real ist ic suggested so lu t i ons as s h o w n in F igure 1 8 1 . In t he pu re l y op t i ca l so lu t i ons we have n o t d is t ingu ished be tween t he d i f f e r e n t par t so lu t ions w i t h m i r r o r s , lenses and pr isms in F igure 180 , b u t so lu t i ons t h a t i nc lude op t i ca l f ib res are s h o w n separate ly , as t h e y are essent ial ly d i f f e r e n t f r o m t he o thers .

The basic s t ruc tu re w h i c h was f o u n d t o be m o s t su i table is s h o w n in deta i l in F igure 182 . T h e s ta r t ing p o i n t is t he s o l u t i o n n u m b e r 2 in F igure 1 8 1 , and the f o l l o w i n g par t so lu t ions f r o m Figure 180 —

OPTICAL

1 ^

^ΖΤΖΆ

FIßR'E OPTIC BUNDLE

\ OPTICAL/PHÓfÓQI^APHIC

fjam

W 5£

ra

•/////////A

^ Pkoto^rapUic

peeper

Figure 181 Showing the fourteen best basic structures

Figure 182 The best basic structure

FUm

181

fJicroscope

hAorabU Lens (d^UmUation)

Abhe'^s presto rf > (onentatíonj

Tiltit^'ß mirror (cívtsst/icatioti)


5.3 Quantif ied structure

O n the basis o f t h e chosen basic s t ruc tu re in F igure 182 a n u m b e r o f c ruc ia l spec i f i ca t ions and t he ma in data mus t be la id d o w n , so t h a t a k a r y o t y p e o f t h e desired q u a l i t y can be p r o d u c e d . T h e mos t i m p o r t a n t data o f t he c o n s t i t u e n t sub-systems are e x a m i n e d and dec ided o n ( t ype o f m ic roscope , f i l m cassette, length o f l i gh t rays, e tc) and a f te r t h a t , m o d e l l i n g o f var ious q u a n t i f i e d s t ruc tu res can take p lace, as descr ibed in Chap te r 2. In t h e f i r s t instance a

n u m b e r o f sketches are made , as s h o w n in F igure 183 . These, however , can o n l y give a ce r ta in general impress ion o f t he poss ib i l i t ies , w h i l e a m o r e de ta i led assessment o f t he q u a n t i f i e d s t r u c t u r e requi res a th ree-d imens iona l s t r uc tu re m o d e l . Th is is made o f p last ic f o a m in such a w a y t h a t all t h e e lements can be easi ly m o v e d a b o u t . F igure 184 shows a n u m b e r o f t he best q u a n t i f i e d s t ruc tu res .

SYMBOLS

Μ

Kiicroscope

F

Film cassette

F5

K^ovinj system

or

Μ

o

ffl

o

1«

i E M

Ο

Ο 5

Ys η

Μ L

Figure 183 Quar)tified structures on ttie basis of the best basic structure shown in Figure 182

Case history : chromosome apparatus 183

The th ree-d imens iona l s t ruc tu re models make i t possible t o evaluate such aspects as w o r k i n g space f o r t he ope ra to r , mechanica l c o m p l e x i t y , heat ( f i l m n o t t o o close t o t he l a m p ) , he igh t , w i d t h and d e p t h o f t he i n s t r u m e n t etc. O n t he basis o f such an eva lua t ion the q u a n t i f i e d s t ruc tu re m a r k e d B—9 in Figures 183 and 185 is chosen .

T h e chosen s t ruc tu re is s h o w n in greater deta i l in F igure 184 . T h e ope ra to r has in f r o n t o f h i m a screen on w h i c h is p ro jec ted a p i c tu re o f t he cel l w i t h the c h r o m o s o m e s . I n f o r m a t i o n o n the pos i t i o n and o r i e n t a t i o n o f t h e chosen c h r o m o s o m e is t ransfe r red mechan ica l l y t o the movab le lens ( three

d i f f e r e n t p ro j ec t i ng lenses) and t o t he A b b e ' s p r i sm . In th i s w a y t h e p i c tu re o f t he desi red c h r o m o s o m e is focussed and o r i e n t a t e d . T h e t i l t i n g m i r r o r , w h i c h p e r f o r m s the c lass i f i ca t ion o f the c h r o m o s o m e p i c t u r e , is pos i t i oned t h r o u g h a m o v i n g system t h a t is ac t i va ted by a k e y b o a r d w i t h a c o n t r o l k n o b f o r each c h r o m o s o m e .

A p a r t f r o m the k a r y o t y p e , the c h r o m o s o m e appara tus mus t also be able t o p h o t o g r a p h the w h o l e ce l l . Th i s t o t a l p i c t u r e can be t a k e n w h e n t he d iaph ragm is r emoved and t he t i l t i n g m i r r o r is p u t in t he m i d p o s i t i o n .

T i l t ing m i r r o r

F i l m c a s s e t t e

Mov ing s y s t e m

Abbe's p r i s m

M o v e a b l e l ens

K e y b o a r d

Figure 184 The ciiosen quantified structure

184

Figure 185 Quan ti fied three-dimensional structures modelled in plastic foam. Some of the elemen ts are fixed on spikes, so that they can be easily moved around

185


186 Case history: ctiromosome apparatus

5.4 Form of the total system

D u r i n g t he w o r k o f f o r m designing t he c h r o m o s o m e apparatus there is i n t e rac t i on be tween t he w o r k o n the o u t e r f o r m and t he f o r m o f t he e lements , as is genera l ly expressed in t he p r o d u c t synthesis. T h e desc r ip t i on on t he f o l l o w i n g pages o f t he w a y in w h i c h t he f o r m o f t he t o t a l sys tem is dec ided o n , mus t t he re fo re be seen as paral lel t o t h e nex t sec t ion on the f o r m o f t he e lements .

T h e q u a n t i f i e d s t ruc tu re in F igure 185 is t aken as the s ta r t ing p o i n t . As the f i l m cassette mus t n o t be exposed t o false l igh t , a n u m b e r o f t he c o n s t i t u e n t e lements m u s t be enclosed in a l i g h t p r o o f screening. The very f i r s t rough design proposals are ar r ived at by va ry ing the f o r m geome t r y and the f o r m d i v i s i on , as s h o w n in Figures 186 and 187 . T h e pages f o l l o w i n g F igure 194 descr ibe h o w the design is g radua l l y chosen.

T h e ideas are m o d e l l e d in var ious ways as t h e w o r k progresses. D e p e n d i n g o n t h e s i t u a t i o n rough sketches, scale d raw ings , and th ree-d imens iona l mode ls in p last ic f o a m , w o o d and ca rdboa rd are used. These mode ls have been very i m p o r t a n t in c o n n e c t i o n w i t h t h e cho ice o f f o r m c o n c e p t , see Figures 190 and 194 .

T h e c r i te r ia t h a t c o u n t w h e n choos ing be tween a l te rna t i ve designs, s tem f i r s t o f all f r o m t h e user and f r o m the p r o d u c t i o n . As fa r as the user is c o n c e r n e d , i t is a ques t i on o f w o r k i n g pos tu re , access ib i l i t y , c lean ing, a d j u s t m e n t and ma in tenance , psycho log ica l fac to rs ( h o w is t he apparatus exper ienced?) and appearance ( u n i t y , o rder , visual ba lance) . F r o m t h e p r o d u c t i o n c o m e c r i t e r i a in c o n n e c t i o n w i t h t he m a n u f a c t u r i n g process, cho ice o f ma te r i a l , p ro d u c t i o n quan t i t i es and assembly.

187

SCALE 1:10

Operativy area

^ / ^

Figure 186 The starting point for form designs is obtained by drawing contour lines closely around the elements to be screened. Varying the form geometry gives the first rough form design suggestions

1 8 8

FOm DIVISIOKJ

•Starting point

i

Figure 187 Variation of form division. These sl<etches form the starting point for a number of the suggestions on the following pages

Figure 188 The first series of form concepts

Figure 189 A general problem is examined, namely the form design of the screen around the operator's mirror. Form geometry and form division are used as variation parameters

Figure 190 A number of detailed form concepts which appear fairly realistic. A three-dimensional model of the suggestion bottom right showed, however, the unfortunate psychological effect that the apparatus is felt to be oppressive, almost

like a wall in front of the operator

192

Mecessarif arefis of mteñal 6H open design

Figure 191 On the basis of the experience gained from the previous suggestions we can examine the possibilities of more open form designs. At the top can be seen the areas the elements occupy, and three possible areas of material are shown

Figure 192 Examination of tfie problems surrounding a partly open framework. Variation of the form division is shown below

194

Figure 193 Two realistic design suggestions

195

Figure 194 Form models corresponding to the two suggestions in Figure 193. Before the final choice can be made one form model must be painted. This makes it possible to assess whether the problems of the visual balance indicated in

Figure 192 can be overcome by an appropriate choice of colour


5.5 Form of the elements

T h e design o f t he e lements cons t i t u tes a very c o m plex series o f ac t iv i t ies , p a r t l y because there are m a n y elements o f w i d e l y d i f f e r e n t character , p a r t l y because the i r detai ls are designed s imu l taneous l y w i t h the cho ice o f mater ia ls , d imens ions and surfaces, and f i n a l l y , as a l ready m e n t i o n e d , because the externa l f o r m is c losely connec ted w i t h t he f o r m o f t h e e lements. F i rs t , i t mus t be emphasised t h a t the re is an i n te rmed ia te stage invo lv ing decis ions on subsystems, such as a t rans fer mechan ism f r o m v iew f i nde r t o p ro jec t i ng lens, and a c o n t r o l system t h a t t ransfers i n f o r m a t i o n f r o m the k e y b o a r d t o the t i l t i n g m i r r o r . These sub-systems are t rea ted in exac t l y t he same w a y as the t o t a l sys tem, t h a t is t o say t h a t one goes t h r o u g h the stages o f basic s t r uc tu re , q u a n t i f i e d s t r uc tu re , etc . co r respond ing t o a new p r o d u c t synthesis on a smal ler scale. A n examp le is s h o w n in F igure 1 9 5 , w h i c h deals w i t h t ransmiss ion mechan isms t o the t i l t i n g m i r r o r . F igure 196 shows h o w s t ruc tu re va r ia t i on can be app l ied t o such a sub-sys tem.

T h e f o r m design o f t he f r ame is i l l us t ra ted in Figures 197 and 198 . These show h o w t h i n k i n g in te rms o f f u n c t i o n a l surfaces gives a clear s ta r t ing

p o i n t f o r a n u m b e r o f suggest ions, whe re t he a r rangement o f t h e areas o f mate r ia l is var ied . T h e f r a m e is an examp le o f t h e w a y in w h i c h t h e f o r m o f an e lemen t is connec ted w i t h t h e external f o r m o f t h e appara tus , as par t o f t he f r a m e is v is ib le and even cons t i t u tes an essential par t o f t h e ex te rna l f o r m .

T h e f u r t h e r one advances in de ta i l i ng t he e lements o f the c h r o m o s o m e appara tus , t he mo re t h e charac ter o f t he f o r m design w o r k is a l te red t o w a r d s dec id ing o n a n u m b e r o f detai ls in c o n n e c t i o n w i t h t he f u n c t i o n a l surfaces. I t is f i r s t o f all a ques t i on o f dec id ing on t h e po in t s where the e lements are t o be j o i n e d toge the r , as s h o w n , f o r instance, in F igure 199 , w h i c h deals w i t h t h e base b o x and t he cover ing screens. One o f t h e ex te rna l f u n c t i o n a l areas o f great i m p o r t a n c e is t he v i e w f i n d e r s h o w n in F igure 2 0 0 .

T h e c r i te r ia f o r t h e design o f t he e lements are m o s t l y conce rned w i t h t w o th ings . F i rs t t he f u n c t i o n , i.e. p rec is ion , r e l i ab i l i t y , s t ab i l i t y , s t rength and r i g i d i t y , and second ly t he p r o d u c t i o n , m a n u f a c t u r i n g process, p r o d u c t i o n quan t i t i es , assembly , and as a consequence o f these an essential c r i t e r i o n — p r o d u c t i o n costs.

197

PUr\ of siiniñi€¿r(f

The mirror mtAst be tcUabCe in two directions at nykt tingles.

filhi cassette

If tke mirror CS tdbed io the extent of finite V the ray is (ottered2V

TKANSMISSIOKJ SJECHAKJISMS: Transmission of a morement in the

fiimpLfine to tke m error-with tke tutrnin^ angle halted

Figure 195 Basic structures for transmission systems for a tilting mirror

1 9 8

Figure 196 Variation of quantified structure for a tilting mirror. Ttie chosen structure is shown at the bottom right on the final version

199

1 3 0

Space needed f(?r kands

Possible arrangement of tke lomr part of tke frange o.^.

Figure 197 The first stages in the form design of the frame. Top, the functional surfaces are indicated and the banned areas made clear. Bottom, arrangement of the areas of material are examined

2 0 0

Figure 198 The form design of the frame and the total form design are closely connected. In accordance with Figure 193 a total form design is chosen where part of the frame in the shape of a column is visible. Various areas of material with a

column are shown above. Below, the chosen frame

2 0 1

-Τ

1

/ /

J '

1 CT

Joint here

Fram-e nsMe from mfronet

Figure 199 A base box and covering screens. Examination of possibilities of lightproof joints tfirough varying the functional surfaces

2 0 2

Variatton of JtAyictíoyicil surfaces for /infers

parffinneters: number, arran^enierit^ dLmenscon^ form.

Arranqetyfenb

Ñumber/firranfiement o)mo)Cö)o

Dimenscon

Fotm qeometrti

Porous/sponji)

io)

Figure 200 Variation of functional surfaces for tfie viewfinder. Tfie design cfiosen is shown in the photograph

2 0 3

Figure 201 Tlie completed chromosome apparatus (Courtesy of Lab. of Engineering Design, The Technical University of Denmark)

2 0 4 Case history: chromosome apparatus

T h e design o f all t h e e lements in the c h r o m o s o m e apparatus is dec ided a f te r d raw ing up sketches and plans, and t he e lements are f i n a l l y spec i f ied in a set o f w o r k i n g and assembly drawings w h i c h f o r m t h e basis f o r t he p r o d u c t i o n . When the apparatus is assembled t he t i m e has c o m e f o r tes t ing , and f o r a real ist ic eva lua t ion o f w h e t h e r i t ac tua l l y possesses the expec ted qual i t ies . Smal l co r rec t i ons and imp rovemen ts are added , and t h e c o m p l e t e d c h r o m o some apparatus appears f i n a l l y as s h o w n in F igure 2 0 1 .

I t mus t once m o r e be emphasised t h a t n o t all t h e stages in the p ro jec t have been descr ibed in th is case h i s t o r y , (see the d iagram in t he marg in o n page 1 8 3 ) . A n u m b e r o f exper imen ts conce rn ing phys ica l feas ib i l i t y , the e lect r ica l c o n t r o l sys tem, var ious ca lcu la t ions , as we l l as w o r k i n g drawings have been o m i t t e d .

T h e case h i s to r y as o u t l i n e d above has an essential a im w h i c h is t o f o r m a con t ras t t o t h e sys temat i ca l l y d r a w n up b u t u n c o n n e c t e d examples t h r o u g h o u t

the b o o k , especial ly in Chap te r 2 . T h r o u g h a case h i s t o r y i t is possible t o s h o w t h e c o n n e c t i o n be tween t he search f o r ideas and eva lua t i on , and t o s h o w h o w s i tua t ions arise in w h i c h t h e f o r m m e t h o d s can be app l i ed . F i n a l l y a d i f f e rence in t he t e c h n i q u e o f m o d e l l i n g m a y be observed (especial ly d r a w i n g tech n i q u e ) . T h e examples o u t o f c o n t e x t m u s t i l lus t ra te a m e t h o d as c lear ly as possib le, w h i l e in t he actua l a p p l i c a t i o n o f t h e m e t h o d s i t is i m p o r t a n t t o be able t o h u n t d o w n so lu t i ons as q u i c k l y as possible.

F r o m t h e s t u d y o f t h e c rea t i on o f t h e c h r o m o some apparatus i t is ev iden t t h a t in t he f i na l instance the sys temat ic m e t h o d s descr ibed in Chap te r 2 m a y be app l i ed in t w o ways . One is e x a c t l y as descr ibed i.e. f o r a sys temat ic survey o f t h e possible so lu t i ons . T h e o t h e r - and perhaps m o s t i m p o r t a n t - w a y is t o acqu i re the a t t i t u d e b e h i n d t h e m e t h o d s , so t h a t one a u t o m a t i c a l l y t h i n k s in te rms o f t he ideas and va r ia t i on pa t te rns descr ibed, and o n l y uses t he m e t h o d s consc ious ly in pa r t i cu l a r l y d i f f i c u l t o r c r i t i ca l s i tua t ions .

Index

A b a c u s , 19 A b b e ' s p r i s m , 1 8 0 , 1 8 5 A c c e s s i b i l i t y t o m a c h i n e , 1 2 6 A e s t h e t i c c r i t e r i a , 1 2 , 6 0 , 1 3 4 , 1 4 3 , 1 4 4 , 1 5 4 A n t h r o p o m e t r y , 1 2 4 A p p e a r a n c e , 5 , 4 2 . 7 8 , 8 4 , 9 0 , 9 1 , 1 0 0 , 1 3 4 , 1 4 0 , 1 4 3 , 1 7 1 ,

184 A s s e m b l y processes, 1 0 2 , 1 0 6 , 1 1 4 , 1 1 5 , 1 8 4

s u b - o p e r a t i o n s , 1 1 4 , 1 1 5 A u t o m a t i c l a the , 169 A u t o m a t i c t e a m a k e r , 9 - 1 3 , 1 5 , 4 2 - 4 6 , 7 7 , 9 0 , 1 6 7

Bal ing p u m p , 3 6 , 3 7 Banned areas, 6 0 , 6 3 . 6 8 , 6 9 Bear ings, 7 6 B e a u t y , 1 4 3 , 1 4 4 , 157 Boi le rs , 1 3 7 B o t t l e o p e n e r , 4 8

D i m e n s i o n s , 7, 9 , 1 3 , 2 2 , 3 6 , 5 2 . 6 0 - 6 2 , 6 6 , 6 8 , 8 4 , 9 5 , 9 7 , 1 0 7 , 1 1 6 , 1 3 0 , 1 5 3 , 154

D i r t , 1 1 6 , 1 1 7 , 1 3 8 D i s t r i b u t i o n f a c t o r s , 1 1 6 D u r a b i l i t y , 7

E c o n o m i c s c r i t e r i a , 1 3 , 7 5 , 9 9 , 1 0 6 , 1 0 8 , 1 0 9 , 1 1 4 , 1 2 5 E f fec t iveness , 4 2 E l a s t i c i t y , 1 2 2 E l e c t r i c i t y m e t e r , 1 0 4 E l e m e n t s ,

a r r a n g e m e n t o f , 3 2 , 3 4 , 4 2 , 4 6 , 6 0 , 6 8 , 1 5 1 , 1 5 4 , 1 5 5 design o f , 13 , 2 2 , 2 4 , 2 6 , 2 8 , 3 2 , 3 4 , 3 6 , 4 8 , 6 3 . 7 7 , 8 9 ,

1 1 8 , 1 9 6 d i v i s i o n o f , 7 4 — 7 6 , 1 0 2

E m e r g e n c y s t o p p i n g , 1 2 5 , 1 3 0 E n v i r o n m e n t , 3 , 1 3 7 , 1 3 9 E r g o n o m i c s , 1 2 3 , 1 2 6 E x c a v a t o r , 4 0 , 4 1 , 1 5 0 , 1 7 0

C a l c u l a t o r s , 1 9 , 7 8 - 8 0 Car jacks , 19 C h r o m o s o m e a p p a r a t u s , 1 7 5 — 2 0 4 C l a m p s , 6 2 C lean ing , 7 8 , 1 2 5 , 1 3 2 Cof fee m a k e r s , 2 1 - 2 3 Cogwhee ls , 9 8 C o l o u r , 1 5 4 C o m p a n y i d e n t i t y , 1 0 0 C o n t r a c t s , 9 9 C o n t r o l areas, 1 3 0 - 1 3 4

design o f , 1 3 3 - 1 5 8 C o n v e y o r be l ts p u l l e y s , 8 5 - 8 8 , 103 C o r r o d i n g f u m e s , 1 1 6

D a m p , 1 1 6 , 1 1 7 , 1 3 8 D a m p v i b r a t i o n s , 137 D e l i m i t a t i o n , 1 7 7 , 1 8 0 Design, 6 , 7 , 1 2 , 13 . 2 1 , 4 2 . 5 0 . 6 0 , 6 6 , 9 6 , 9 9 . 1 0 6 . 1 2 3 .

1 2 4 , 1 2 6 , 1 3 7 , 1 3 8 s o l u t i o n s , 2 1 , 2 2

Designer, 6 , 1 4 , 8 9 , 9 0 , 9 5 , 9 9 , 1 0 6 , 1 2 1 , 1 2 3 , 1 4 3 , 147 D e s t r u c t i o n , 6 . 9 6 . 1 3 9 Dia lys is c e i l , 1 3 2

F a s h i o n , 1 3 5 F i r e , 1 2 5 F o r k j o i n t s , 6 6 , 6 7 F o r m , 3 , 4 , 7 , 9 , 1 3 , 1 5 , 3 6 , 4 8 , 9 5 , 9 8 , 9 9 . 1 1 8 . 1 2 1 . 143

c o n c e p t s , 6 4 . 6 6 . 6 7 , 7 0 , 7 1 , 7 5 , 7 6 . 8 6 . 8 7 , 8 8 , 1 0 2 , 1 0 4 , 1 0 5 , 1 0 6

des ign , 1 9 , 9 4 - 9 6 , 1 0 0 , 1 0 8 , 1 0 9 , 1 1 5 - 1 1 7 , 1 2 2 , 1 9 6 , 2 0 0

d i v i s i o n m e t h o d , 7 4 - 7 8 , 8 1 , 8 4 , 1 0 4 , 1 0 5 . 1 9 3 e l e m e n t s , 1 3 , 1 4 7 , 1 4 8 . 1 5 1 . 1 6 0 , 1 6 3 , 1 8 6 r e s t r i c t i o n o n , 6 0 synthes is m e t h o d s , 2 1 , 8 9 v a r i a t i o n , 4 8 . 5 0 . 6 1 , 6 6 , 6 8 , 8 9 , 9 0 , 1 0 2

F u n c t i o n (o f p r o d u c t ) , 5 , 7 , 9 , 19 , 2 1 , 3 6 , 6 2 , 7 4 , 9 5 , 1 0 9 , 1 1 8 , 1 2 1 , 1 2 2 . 1 3 2

sub f u n c t i o n s , 1 9 , 2 6 F u n c t i o n f a c t o r s ,

f e a s i b i l i t y o f , 121 i n t e r v a l , 121 q u a l i t y o f , 1 2 1 , 122

F u n c t i o n a l surfaces, 4 8 - 5 0 , 5 2 , 5 6 , 5 7 , 6 0 , 6 1 , 6 3 , 6 6 , 6 8 , 6 9 , 7 5 , 8 4 , 8 5 , 8 9 , 1 0 6 , 1 1 8 , 1 2 1 , 196

a r r a n g e m e n t o f . 5 2 - 5 6 , 6 1 , 8 4 , 8 5 , 8 6 d i m e n s i o n o f , 5 2 - 5 6 , 6 0 , 6 1 , 6 2 , 6 6 , 6 8 . 8 4 , 8 5 , 8 7

2 0 5

2 0 6 Index

F u n c t i o n a l surfaces continued e x t e r n a l , 4 8 , 5 0 , 5 2 , 1 2 2 g e o m e t r y , 5 2 , 5 3 , 5 5 , 5 6 , 6 0 , 6 1 , 6 2 , 6 6 , 6 8 , 8 4 , 8 5 , 8 7 i n t e r n a l , 4 8 , 5 0 , 5 2 m a x i m u m , 5 5 , 5 6 , 5 8 , 5 9 , 6 0 , 8 4 , 8 5 m i n i m u m , 5 5 , 5 6 , 5 8 , 5 9 , 6 0 , 8 4 , 8 5 n u m b e r , 5 2 - 5 6 , 6 1 , 8 4 . 8 5 , 8 6 v a r i a t i o n p a r a m e t e r s , 5 2 , 5 5 , 6 3 , 6 6 , 7 7 , 8 4

O p e r a t i o n o f m a c h i n e r y , e m e r g e n c y , 1 2 5 n o r m a l , 1 2 5 - 1 3 3 o c c a s i o n a l , 1 2 5 , 1 3 2

O p e r a t i o n o f p r o d u c t , 9 2 , 1 8 7 O p e r a t o r s i t u a t i o n , 1 0 6 , 1 0 8 , 1 1 4 , 1 2 5 , 1 2 6 , 1 8 0 O r d e r , 1 4 4 , 1 5 4 , 1 8 6 O r i e n t a t i o n , 1 7 7 , 1 8 0

G e o m e t r y o f f o r m , 1 0 6 , 107 G r i n d i n g m a c h i n e , 1 2 9

H a b i t , 1 3 5 , 1 3 6 H a n d l i n g , 7 , 4 2 , 1 2 5 Hardness, 122 Heat , 137 H y d r a u l i c press, 6 3 , 6 4 , 6 5 , 1 2 9

I n p u t mate r ia ls , 1 0 7 , 108 i n s t a l l a t i o n , 125 I n v e s t m e n t , 1 0 8 I rons , 119

J o i n t s , 1 6 3 - 1 6 5

K a r y o t y p e , 1 7 6 , 1 7 7 , 1 8 2 , 1 8 5

Labe l l ing m a c h i n e s , 3 9 Licences, 9 9 L i g h t i n g , 1 3 0 L ightness , 1 6 6 - 1 6 8 Lines, 1 6 0

M a c h i n e r y , 1 0 7 , 1 0 8 , 1 2 4 , 1 2 5 , 1 3 0 M a i n t e n a n c e o f m a c h i n e , 1 2 5 , 132 M a n u f a c t u r i n g process, 5, 6 , 6 6 , 7 5 , 7 6 , 7 8 , 8 4 , 8 9 , 1 0 2 ,

1 0 6 , 1 0 7 , 1 0 9 , 1 1 4 , 1 3 8 , 1 4 5 , 1 4 7 , 1 8 7 , 1 9 6 e c o n o m i c s o f . 1 1 1 , 1 1 3 , 1 1 4 - 1 1 7

M a r k e t c o n d i t i o n s , 1 1 6 Mater ia ls , 7 , 1 3 , 8 4 , 9 0 , 9 7 , 9 9 , 1 0 0 , 1 0 2 , 1 0 5 , 1 1 0 , 1 1 1 ,

1 1 3 , 1 4 6 , 1 5 1 , 1 9 5 M a x i m u m f u n c t i o n a l surfaces, 5 5 , 5 6 , 5 8 , 5 9 , 6 0 , 8 4 M i c r o s c o p e , 2 6 , 2 7 , 6 8 - 7 4 , 1 3 4 , 1 5 0 M i n i m u m f u n c t i o n a l sur faces, 5 5 , 5 6 , 5 8 , 5 9 , 6 0 , 8 4 Mode ls , 4 6 , 9 0 - 9 3 , 1 3 4 , 1 4 0 , 1 4 8 , 1 4 7 , 1 8 2 , 1 8 6 , 1 9 6 ,

2 0 3 M o d u l e s , 158 M o v e m e n t , 171

Noise , 1 2 6 , 141

O f f s e t w r i t i n g m a c h i n e , 146 O p e n process area , 1 2 7 , 1 3 0 O p e r a t i n g area, 1 2 7 , 1 3 0

P a c k i n g , 1 1 6 Parameter s e n s i t i v i t y , 1 2 2 Parts, 1 0 2 P a t t e r n r e g i s t r a t i o n , 1 0 0 P a w l , 7 5 P e r c e p t i o n , 1 3 0 , 133 Pet ro l p u m p s , 8 3 P h o t o c o p i e r , 1 0 1 , 1 0 8 , 1 1 4 , 1 6 8 Physical d i v i s i o n , 7 4 Planes, 1 6 0 P n e u m a t i c m o t o r s , 8 1 Prec is ion , 1 9 6 Prices, 4 2 , 9 8 Process t e c h n i c i a n , 8 9 , 1 0 6 P r o d u c t ,

design o f , 7 7 , 8 9 , 9 9 , 1 0 0 f a c t o r s , 9 5 , 9 6 , 9 9 , 1 1 8 l i f e o f , 6 , 9 5 , 9 6 p r o p e r t i e s o f 7 , 9 5 , 9 7 , 1 4 3 q u a l i t y o f , 1 0 7 , 1 0 8 syn thes is , 8 , 9 , 1 4 , 2 1 , 9 5 , 1 8 6 w e i g h t , 1 1 6

P r o d u c t i o n , assembly processes, 1 0 2 costs , 1 9 6 f a c t o r s , 9 6 , 1 0 2 m a n u f a c t u r e o f p a r t s , 1 0 2

P r o p o r t i o n s , 1 5 7 , 1 5 8 Psycho log ica l f a c t o r s , 1 3 4

R e c y c l i n g m a t e r i a l , 139 R e l i a b i l i t y , 7 , 1 2 2 , 1 9 6 Repa i rs , 1 2 5 , 132 R h y t h m , 1 5 4 , 1 5 5 R i g i d i t y , 1 2 2 , 1 9 6 R o a d r o l l e r s , 2 8 - 3 3

S a f e t y , 7, 1 0 0 , 1 2 2 , 1 2 6 Sales, 9 6 , 1 1 6 Service p o l i c y , 9 9 , 1 3 2 Shape, see F o r m S o c i e t y , 1 0 0 S o l u t i o n s , 1 4 , 1 5 , 2 1 , 2 2 , 2 8 , 3 4 , 3 6 , 4 2 , 6 6 , 9 5 , 1 4 0 , 1 8 0

range o f , 3 4 Space, 4 2 , 6 0 , 9 2 , 117 Spr ings , 103 S p r i n k l e r valves, 6 1 S t a b i l i t y , 1 2 4 , 1 6 9 , 1 9 6

Index 2 0 7

S t o r i n g c o n d i t i o n s , 117 S t r e n g t h , 1 2 2 , 1 9 6 S t r u c t u r e , 7 , 8 , 9 , 1 3 , 19 , 2 2 , 3 6 , 8 9 , 9 5 , 1 0 3 , 1 4 3

basic , 3 9 , 4 0 , 4 2 , 4 4 , 4 8 , 1 7 9 , 1 8 0 , 1 9 6 , 197 m o d e l l i n g , 4 6 q u a n t i f i e d , 1 2 , 2 1 , 2 2 , 2 4 , 2 6 , 2 8 , 3 4 - 4 4 , 4 6 - 4 8 , 6 8 ,

1 9 1 , 1 9 4 , 2 0 5 , 2 0 7 v a r i a t i o n , 2 1 , 2 2 , 2 4 , 2 6 , 3 6 , 3 8 , 4 2 , 8 9

S t y l e , 1 3 5

T e l e p h o n e , 9 3 Test t u b e f i l l i n g m a c h i n e , 4 6 , 4 7 , 5 6 , 5 7 , 5 8 , 5 9 , 6 0 , 9 2 .

121 T h r e a d sp ind les , 113 T o l e r a n c e r e q u i r e m e n t s , 107 T o o l s , 1 0 7 - 1 0 9 T r a n s p o r t i n g p r o d u c t , 1 1 6

U n i t y , 1 4 4 , 1 5 8 , 187 User, 1 1 8

V a c u u m cleaners, 2 4 , 2 5 V a c u u m p u m p , 153 V a l v e , 3 V a r i a t i o n p a r a m e t e r s , 5 2 , 5 5 , 6 3 , 6 6 , 7 7 . 8 4 V e r t i c a l d r i l l . 153 V i b r a t i o n m e t e r , 1 6 7 V i s u a l ba lance , 1 5 1 - 1 5 3 , 1 6 0 , 1 8 6 V isua l d i v i s i o n , 7 4

W a r e h o u s i n g , 1 1 6 , 1 1 7 W a t e r i n g cans, 8 2 W e i g h t , 1 1 6 , 1 3 2 , 1 6 9 , 1 7 0 W o r k i n g p o s t u r e , 1 2 3 , 1 2 6

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