rapid prototyping.docx (2).doc

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Introduction

The competition in the world market for manufactured products has intensified tremendously

in the recent years. It has become vital, if not necessary for the newer products to reach themarket as early as possible, before our competitor introduces it. Thus to bring the products to

the market as early as possible, several processes in its designing and its manufacturing have

been squeezed both in terms of time and material resource. To do this, several new

techniques need to be evolved in terms of designing, manufacturing, tooling and finishing,

and many have been evolved in the past two to three decades. Most of these are technology

driven and involve computers in some or the other way.

One of these time reducing and material saving process is apid !rototyping. apid

!rototyping is a method of producing fully functional" non#functional prototypes of products

by additive"stack manufacturing.

!rototyping is not at all a new process. It has been used for many centuries. $ven when the

early man made tools, they were a kind of prototype, although earlier the prototypes were

made by subtractive machining, i.e. the conventional machining processes, but it has changed

quite a lot. The older subtractive method of prototyping involved the removal of material

from a block of metal, which involved waste of material and the prototype being made by the

operator, was not accurate. %owever apid !rototyping allows us to create the prototype

directly from the design made on any &'( software, with high level of accuracy and

precision and in lesser time. In this technique, the basic concept is to make a product by

spreading layers of material over the previous layer. This makes it possible to make those

ob)ects which have hollow sections or parts which are not accessible by the conventional

machining tools.

*ith the advent of apid !rototyping it has become quite easy for the industries to research

and develop new products at a relatively faster rate, as they can analyze their products on

analyzing software+s like ansys, and then make prototypes of those products to be tested in

physical world.

This technique also helps the industries in gaining the opinion of consumers on the product

and in predicting the need of the consumers by allowing such prototypes to be tested byselected group of people, thus getting feedback on the product directly from the customer,

and that to without setting up a pro)ect to manufacture the product. This gives the designers

an insight of the needs of the mass and they can accordingly change the design and other

parameters of the product so as to make the product market ready.

apid !rototyping is a vast topic to study, and in this report we will be discussing the use of

apid !rototyping in various fields, various methods used for apid !rototyping, its

advantages limitations and its future scope in the manufacturing industry.

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Why Prototype & Why Rapid Prototyping?

The big question that must arise in our mind is -*hy !rototype+ *hy spend money, time

and energy on making something that you could not even sell *hy not start the productionso that I could get my product in the market as early as possible, so as to defeat my

opponents

/ut in a competitive market can we risk to launch a product in market which has not been

tested under its working conditions, or can we set up the production unit and then test the

final products for their usability.

*ell I don+t think any company could afford any of the above two cases, so the answer to our

problems is a !rototype.

0' !rototype is the first or original e1ample of something that has been or will be copied ordeveloped2 3uch a physical ob)ect can be easily tested under various real life conditions that

the original product may have to face. It can also be used to get hold of the opinion of the

consumers, so as to develop the product e1clusively for the targeted customers.

4et+s take the e1ample of an arm chair. It is not )ust made by attaching different pieces of

wood. *e actually make different prototypes according the angles at which the body should

be bent and then these prototypes are then tested for the most comfortable set, which is then

given to certain people to test and give their feedback. Only then the armchair is sent for

manufacturing

' very good e1ample of the above need is the mobile phone dummies. The mobile handset

manufacturing companies make dummies of the mobile handsets 5sometimes fully functional6

and these are presented to a group of people handpicked according to their preferences and

their tastes, and the group then gives its opinion on the mobile handsets, which ranges from

-how good is the grip of the phone+ to -how the touch or keypad responds+.

Thus it is the vital requirement of every manufacturing company to make a prototype to test

on and then set up the production unit for the tested and passed design.

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7ig. 8 !rototype of a /arcode 3canner

9ow comes the ma)or question, I can make a prototype, or get it made by an operator, then

why spend millions on rapid prototyping *ell at this stage, time is money, and it is time that

we save by rapid prototyping. The same prototype that would be made by an operator in a

week could be made in 8: to 8; hours by rapid prototyping, so the question is why not usethe fastest method and save time i.e. indirectly money by using apid !rototyping.

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Historical Development of Rapid Prototyping

The development of rapid prototyping is very closely related to the advent of application of

computers in the manufacturing industry. 's mentioned earlier in Introduction, apid!rototyping is not a new technique, but the ma)or advancements in the computer applications

has made it more useful as well as more cost effective.

The emergence of apid !rototyping would not have been possible if it had not been for

&'( i.e. &omputer 'ided (esigning.

The table below gives a chronological history of the development of the technologies relevant

to apid !rototyping.

's it is clear from the above table that the first apid !rototyping 3ystem was developed in

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Fundamentals of Rapid Prototyping

There are various methods of creating a prototype, although they follow the same basic

approach, which can be defined in the following points#>

8. ' model of the component to be prototyped is modeled on a &omputer 'ided (esign

5&'(6 system. The model which defines the part to be made must have closed surfaces

i.e. it must represent an enclosed volume. The model must give all the details related to

the internal and outside surface of the component. 3uch requirements are not necessary

when modeling via solid modeling techniques, as the model modeled is itself a solid

ob)ect.

?. The model made by solid modeling or surface modeling is then converted to a format

known as 3T4 53tereo 4ithography6 file format. The 3T4 file format appro1imates the

surfaces of the model by polygons, that means that the 3T4 file for models which have

curved parts can be very large.

@. ' computer program analyzes the .3T4 file which defines the model, and then slices the

model into very thin cross#sections.

A. These cross#sections are then recreated by the solidification of either the liquids or

powders and then combined to form a @( model. 'nother way is that we use the cross#

sections that are already thin, i.e. solid laminations and these thin laminations are thenglued together with the adhesives to build the required model.

The Bisual epresentation of the above four points is given on the ne1t page, with the

addition of transmission of data and post processing on the prototype, which is seldom

needed in advanced apid !rototyping Machines.

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The above figure provides a clear outline of how a basic apid !rototyping proceeds, 5i.e. the

process chain6 and the basic steps involved in this process.

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Four Key Aspects of Rapid Prototyping

The (evelopment in apid !rototyping can be seen in four ma)or areas which are mentioned

below#>

8. Input

?. Method

@. Material

A. 'pplications

These four are depicted in the ! wheel shown below

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! Input"#

The input refers to the electronic information that is required to define the @( ob)ect. 9ow

this can be done in two ways

a6 $ither by a computer model made by &'( system which can either be a surface model ora solid model. This may look quite a tough task, but actually it is the easy one,

b6 The second method involves the modeling of a physical model. This is a sophisticated

task, and requires data acquisition through reverse engineering. In this method various

techniques are used to acquire the data of the physical ob)ect such as coordinate

measuring machine, or a laser digitizer to capture the data points of the physical model

and reconstruct it on a &'( system.

$! %ethod"#

There are various methods that can be used in !, but all these methods can be generallyclassified into these categories#> !hotocuring, Coining or /inding, Melting and 3olidifying or

7using, and Dluing and Coining. !hotocuring can be further classified into three categories#>

3ingle 4aser /eam, (ouble 4aser /eams, and Masked 4amp.

! %aterials"#

Initially the material can be in any of the three forms, namely 3olid, 4iquid and !owder. In

solid form the material varies from pellets, wires or laminates. The current range of materials

includes paper, nylon, wa1, resins, metals and ceramics.

'! Applications"#

Most of the products made by ! are either finished or touched up before their use. The

applications of ! can be grouped into @ parts#>

a6 (esign

b6 $ngineering analysis and planning

c6 Manufacturing and tooling.

There are a vast range of industries that can benefit from !, some of them being aerospace,automotive, biomedical, consumer, electrical and electronic products.

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(lassification of Rapid Prototyping )ystems

*i+uid ,ased

8. @( 3ystems+ stereo lithography apparatus534'6

?. Ob)et Deometries 4td+s !oly)et

@. (#M$&+s solid creation system53&36

A. $nvisionTec+s !erfactory

:. 'utostrade+s $#(arts

;. &M$T+s splid ob)ect ultraviolet#laser printer 53OE!6

F. $nvisionTec+s /ioplotter

=. apid freeze prototyping


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Widely .sed %ethodsOf the above AG processes, all have some or the other advantages and disadvantages and are

being used by various companies as their signature technique.

Of the above mentioned techniques, lets constrain ourself to a few most important and widely

used processes, they being

3tereolithography

3elective 4aser 3intering

7used (eposition Modeling

Three#dimensional !rinting

4aminated Ob)ect Manufacturing

4aser#engineered 9et 3haping

Multi)et Modeling

4ets continue with the aforementioned methods#>

)tereolithography

3tereolithography 534'#stereolithography apparatus6, launched by @( 3ystems Inc. in 8


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7ig. A 3chematic of 34' !rocess

' lattice structure is also created as a base to prevent the model from sticking to the buildingplatform. Thus, additional hand#finishing will be needed to remove these supporting

structures and to sand any small stubs from the surface .

!hotosensitive materials used in this process are

!'

'/3

!!

and rubber#like materials, etc

!rocess times, tolerances, and surface finish depend on layer thickness, which is controlled

by the amount the platform is lowered into the resin. Denerally, layer thicknesses vary from

G.G:K G.: mm. Thinner layers can be applied with digital light processing using a technique

called perfactory, which is based on the standard 34' process. Instead of describing a cross

section with a laser, a normal beamer covers the entire cross section at once. (ue to the high

resolution of the beamer 5pi1el size> @< Lm6 and the accurate positioning system of the

platform 5layer thickness> ?: Lm6, the parts produced can contain highly detailed features.

/elow is a part produced by 34'#>

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7ig. : ' (M( mirror reproduction using 34'

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)elective *aser )intering

3elective laser sintering 53436 is a process that was patented in 8


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Dood mechanical properties, though depends on building orientation.

!owdery surface

Many variables to control

9o support required

'n e1ample of a part made by 343 is given below#>

7ig. F 'ccurate positioning elements with internal hinges produced by 343

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Fused Deposition %odeling

7used deposition modeling 57(M6, developed by 3tratasys, is the second most widely used

rapid prototyping process. ' filament thread of plastic is unwound from a coil and fed into an

e1trusion head, where it is heated and e1truded through a small nozzle. /ecause the e1trusionhead is mounted on a mechanical stage, the required geometry can be described, one layer at

a time. The molten plastic solidifies immediately after being deposited and bonds to the layer

below.

7ig. = 3chematic of the 7(M process

3upport material is laid down similarly through another e1trusion head. The platform on

which the ob)ect is built steps down by the thickness of a single layer. The entire system is

contained within a heated oven chamber which is held at a moderate temperature above the

glass transition temperature of the polymer. This provides much better control of the process

because stresses can rela1. 's in the 34' process, overhanging features need to be supported.This support material needs to be removed in secondary operations. &ommercially available

water#soluble support materials facilitate this final step. '/3, polycarbonate, and

poly5phenyl6sulfone are commonly used materials in the 7(M process.

&haracteristics>

Office#friendly and quiet.

7(M is fairly fast for small parts.

Dood mechanical properties, so suitable for producing functional parts.

*ide range of materials.

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/hree Dimensional Printing 0DP1

Three (imensional !rinting 5@(!6 technology was developed at the Massachusetts Institute

of Technology and licensed to several corporations. The process is similar to the 3elective

4aser 3intering 53436 process, but instead of using a laser to sinter the material, an ink#)etprinting head deposits a liquid adhesive that binds the material. Material options, which

include metal or ceramic powders, are somewhat limited but are ine1pensive relative to other

additive processes. @( !rinting offers the advantage of fast build speeds, typically ?#A layers

per minute. %owever, the accuracy, surface finish, and part strength are not quite as good as

some other additive processes. @( !rinting is typically used for the rapid prototyping of

conceptual models 5limited functional testing is possible6.

7ig. < 3chematic of Three (imensional !rinting

The @( printing process begins with the powder supply being raised by a piston and a

leveling roller distributing a thin layer of powder to the top of the build chamber. ' multi#

channel ink#)et print head then deposits a liquid adhesive to targeted regions of the powder

bed. These regions of powder are bonded together by the adhesive and form one layer of the

part. The remaining free standing powder supports the part during the build. 'fter a layer is

built, the build platform is lowered and a new layer of powder added, leveled, and the

printing repeated. 'fter the part is completed, the loose supporting powder can be brushed

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away and the part removed. @( printed parts are typically infiltrated with a sealant to improve

strength and surface finish.

9o support structures are required because the surrounding powder particles support

overhanging features. /y adding color to the binder solution, ob)ects can be produced inevery desired color. 3tarch, plaster, medicines 5for producing controlled#dosage

pharmaceuticals6, ceramics, and metals are commonly used materials 5powders6 for @#(!.

&haracteristics>

4imitations on resolution and surface finish.

7ragile ob)ects need to be infiltrated.

'n $1ample of @( !rinted Ob)ect is given below

7ig. 8G @#( printed landscape

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*aminated 234ect %anufacturing

The first commercial 4aminated Ob)ect Manufacturing 54OM6 system was shipped in 8


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7ig. 8? Trumpet prototype using 4OM

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*aser 5ngineered 6et )haping

4aser engineered net shaping or 4$93 is a technology developed by 3andia 9ational4aboratories for fabricating metal parts directly from a computer#aided design 5&'(6 solid

model by using a metal powder in)ected into a molten pool created by a focused, high#

powered laser beam.

' high power laser is used to melt metal powder supplied coa1ially to the focus of the laser

beam through a deposition head. The laser beam typically travels through the center of the

head and is focused to a small spot by one or more lenses. The J# table is moved

in raster fashion to fabricate each layer of the ob)ect. The head is moved up vertically as each

layer is completed. Metal powders are delivered and distributed around the circumference of

the head either by gravity, or by using a pressurized carrier gas. 'n inert shroud gas is oftenused to shield the melt pool from atmospheric o1ygen for better control of properties, and to

promote layer to layer adhesion by providing better surface wetting.

7ig 8@ 3chematic of 4aser $ngineered 9et 3haping

This process is similar to other @( fabrication technologies in its approach in that it forms a

solid component by the layer additive method. The 4$93 process can go from metal and

metal o1ide powder to metal parts, in many cases without any secondary operations. 4$93

is similar to selective laser sintering, but the metal powder is applied only where material is

being added to the part at that moment. 4$93 is the only process where a metal part can be

printed directly without being buried in powder. It can produce parts in a wide range

of alloys, including titanium, stainless steel, aluminum, and other specialty materialsN as well

as composite and functionally graded materials. !rimary applications for 4$93 technology

include repair overhaul, rapid prototyping, rapid manufacturing, and limited#run

manufacturing for aerospace, defense, and medical markets. Microscopy studies show the

4$93 parts to be fully dense with no compositional degradation. Mechanical testing reveals

outstanding as#fabricated mechanical properties.

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The process can also make PnearP net shape parts when itQs not possible to make an item to

e1act specifications. In these cases post production light machining, surface finishing, or heat

treatment may be applied to achieve end compliance.

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%ulti4et %odelling0%7%1

Multi)et modelling 5MCM6 uses multiple print heads to deposit droplets of material in

successive, thin layers. Two ma)or MCM techniques can be distinguished #>

ThermoCetR# ' print head deposits droplets of wa1. /ecause of its relatively fast production,

this technique is marketed to the engineering or design office for quick form studies 5concept

modeling6. %owever, wa1 models can also be used as master patterns for investment casting,

as will be e1plained later.

InBisionR# ' print head )ets two separate materials, an acrylic EB#curable photopolymer#

based model material and a wa1#like material to produce support structures for the model.

7ig. 8A 3chematic of Multi)et Modelling

(ue to the relative good quality of the models, production speed, and surface finish,

applications range from preliminary prototypes to mock#ups for concept proposals or

marketing models.

'n $1ample of products made by Multi)et Modeling is given on the ne1t page#>

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7ig. 8: *a1 Models Made by Multi)et Modelling

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Advantages

apid !rototyping has Manifold advantages#>

apid !rototyping can provide with concept proof that would be required for attracting

funds.

The !rototype gives the user a fair idea about the final look of the product.

apid prototyping can enhance the early visibility.

It is easier to find the design flaws in the early developmental stages.'ctive participation

among the users and producer is encouraged by rapid prototyping.

's the development costs are reduced, apid prototyping proves to be cost effective.

The user can get a higher output.

The deficiencies in the earlier prototypes can be detected and rectified in time.

The speed of system development is increased. It is possible to get immediate feedback

from the user.

There is better communication between the user and designer as the requirements and

e1pectations are e1pressed in the beginning itself

.%igh quality product is easily delivered by way of apid prototyping.

apid prototyping enables development time and costs.

There are many innovative ways in which apid prototyping can be used, such as $nd

Eser &ustomization, 'dditive Manufacturing, apid Tooling, etc.

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Disadvantages

Bery high costs, which have reduced in last few years, but are still quite high, are the

biggest disadvantage of this technique.

Its use in $nd Eser !roducts, i.e. manufacturing finished products by apid prototyping,

is questionable due to the time taken in making a finished product, which is very high as

compared to the conventional methods.

Other than the above two problems the technique is very efficient.

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Future )cope

apid !rototyping is not a new technique, but the new techniques like 'dditive

manufacturing, are a part of development of apid !rototyping.

In future apid !rototyping is e1pected to deliver many such techniques that could change

the way we live. 4et+s discuss two of them, one in near future while other in distant#>

In the coming future, we will be able to make things we need, instead of buying them.

*ith the decreasing cost of @( printers, in the near future it would be possible for every

single person to design and print customized covers for their mobiles and many other

ob)ects.

In contrast to the above point, 9'3' has decided to send a @( printer to the International

3pace 3tation, so that the replacement parts that are carried in the station can be replaced

by a @( printer which could print any part that is needed for replacement. This would

save space for necessary commodities like food and fuel.

'nother new technique although in early stages of research claims to form %uman

Tissues by a technique similar to apid !rototyping, i.e. adding living tissues layer by

layer.

esearchers at the Eniversity of %asselt, in /elgium, successfully printed a new )awbone

for an =@ year old women, who in now able to speak and chew normally with it. 3o in the

coming time there would be no organ donations, )ust print the desired organ and get

going.

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(onclusion

apid !rototyping has changed the way articles were manufactured. It has made things easier

for both the designer as well for the users. *hile it helps the designers to foresee the

problems in his design, it helps the users to tell the designers what the mass demands, so as to

have better and desired products.

This technique, though costly, has opened the new world of manufacturing. 9ew

manufacturing techniques like 'dditive Manufacturing and apid Tooling, are an e1tension

of this technique and with further development, it would help us make better and cheaper

products, and in relatively lesser time.

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References

&hua &.H., 4eong H.7., 4im &.3., apid !rototyping> !rinciples and 'pplications, *orld

3cientific !ublishing &o., III $dition.

4iou 7.*., apid !rototyping and $ngineering 'pplications> ' Toolbo1 for !rototype

(evelopment, && !ress> Taylor and 7rancis Droup, I $dition

Benuvinod !.H.,*eiyin M, apid !rototyping> 4aser#/ased and Other Technologies,

Hluwer 'cademic !ublishers, I $dition

a)a B., 7ernandes H.C., everse $ngineering# 'n Industrial !erspective, 3pringer#

Berlag 4ondon 4imited, I $dition

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