design and development of grass cutting machine using dfma methodology

UNIVERSITI TEKNIKAL MALAYSIA MELAKA

Design and Development of Grass Cutting

Machine using DFMA Methodology

Thesis submitted in accordance with the requirements of Universiti Teknikal

Malaysia Melaka for the Bachelors degree in Manufacturing Engineering

(Manufacturing Design) with Honours

By

MOHD ISHAMMUDIN BIN MOHD YUNUS

Faculty of Manufacturing Engineering

April 2008

UTeM Library (Pind.1/2007)

SULIT

TERHAD

TIDAK TERHAD

(Mengandungi maklumat yang berdarjah keselamatan atau kepentingan Malaysia yang termaktub di dalam

AKTA RAHSIA RASMI 1972)

(Mengandungi maklumat TERHAD yang telah ditentukan

oleh organisasi/badan di mana penyelidikan dijalankan)

(TANDATANGAN PENULIS)

Alamat Tetap: NO 453,Jln Hj Adnan, Kg Gching,

43900,Sepang, Selangor Darul Ehsan

Tarikh:

* Tesis dimaksudkan sebagai tesis bagi Ijazah Doktor Falsafah dan Sarjana secara penyelidikan, atau disertasi bagi pengajian secara kerja kursus dan penyelidikan, atau Laporan Projek Sarjana Muda (PSM). ** Jika tesis ini SULIT atau TERHAD, sila lampirkan surat daripada pihak berkuasa/organisasi berkenaan dengan menyatakan sekali sebab dan tempoh tesis ini perlu dikelaskan sebagai SULIT atau TERHAD.

BORANG PENGESAHAN STATUS TESIS*

UNIVERSITI TEKNIKAL MALAYSIA MELAKA

JUDUL: _______________________________________________________________ _______________________________________________________________

SESI PENGAJIAN : _______________________

Saya _____________________________________________________________________

mengaku membenarkan tesis (PSM/Sarjana/Doktor Falsafah) ini disimpan di Perpustakaan Universiti Teknikal Malaysia Melaka (UTeM) dengan syarat-syarat kegunaan seperti berikut:

1. Tesis adalah hak milik Universiti Teknikal Malaysia Melaka. 2. Perpustakaan Universiti Teknikal Malaysia Melaka dibenarkan membuat salinan

untuk tujuan pengajian sahaja. 3. Perpustakaan dibenarkan membuat salinan tesis ini sebagai bahan pertukaran

antara institusi pengajian tinggi.

4. **Sila tandakan ()

Design and Development of Grass Cutting Machine using DFMA Methodology

2007/2008


(TANDATANGAN PENYELIA)

Cop Rasmi:

Tarikh: _______________________

DECLARATION

I hereby, declare this thesis entitled Design and Development of Grass Cutting Machine

using DFMA Methodology is the results of my own research

except as cited in the reference.

Signature : ...

Authors Name :

Date :


APPROVAL

This thesis submitted to the senate of UTeM and has been accepted as fulfillment of the

requirement for the degree of Bachelor of Engineering Manufacturing (Design). The

members of the supervisory committee are as follows:

Main supervisor

Faculty of Manufacturing Engineering

i

ABSTRACT

This project describes about the implementation of redesign the grass cutting machine by

using the application of Design for Manufacturing and Assembly (DFMA) methodology.

The scope based on the existing grass cutting machine and the appropriate of DFMA

methodology. The method used for gaining the data is from the reassembled the existing

grass cutting machine. From the data achieved, it can be classified into several categories

to be studied. Data will be analyzed by using Lucas Hull method to verify the design

efficiency, handling ratio and fitting ratio to achieve. The tools that used is TeamSET

software. The new proposed design of grass cutting machine drawn using SolidWorks

software based on TeamSET result achieved. Result shown that the design efficiency for

redesign grass cutting machine obtained better percentage rather than the existing design.

From the study, the total part, handling ratio fitting ratio and cost of existing design is

reduced. Eventually, the improvement of redesign grass cutting machine finally will be

able to meet user requirements and satisfactions.

ii

ABSTRAK

Kertas kerja ini menghuraikan tentant perlaksanaan dalam mereka bentuk semula mesin

pemotong rumput dengan menggunakan aplikasi DFMA (Design for Manufacturing and

Assembly). Skop projek adalah memfokus kepada rekabentuk asal mesin pemotong

rumput dan disertakan dengan aplikasi DFMA. Kaedah yang digunakan untuk

mendapatkan data adalah daripada memasang semula mesin pemotong rumput. Hasil data

yang diperolehi akan dikelaskan kepada beberapa kategori sebelum analisa dilakukan.

Kemudian, kesemua data tersebut akan dianalisa dengan menggunakan kaedah Lucas

Hull untuk menentukan kecekapan rekabentuk, nisbah pengendalian, nisbah perhimpunan

sebagai pencapaian objektif projek. Perkakasan yang terlibat adalah perisian TeamSET.

Rekabentuk mesin pemotong rumput yang baru akan di lukis menggunakan perisian

SolidWorks berdasrkan keputusan yang dicapai daripada perisian TeamSET. Keputusan

menunjukkan bahawa kecekapan reka bentuk untuk rekabentuk semula mesin pemotong

rumput memperolehi peratusan lebih baik daripada rekabentuk yang asal. Daripada

kajian, bahagian terjumlah, nisbah pengendalian, nisbah perhimpunan dan kos telah

dikurangkan. Akhirnya, peningkatan rekabentuk semula mesin pemotong rumput

akhirnya akan dapat bertemu keperluan dan kepuasan pengguna.

iii

DEDICATION

For my beloved mother and father

iv

ACKNOWLEDGEMENTS

First and foremost, I would like to express my highest appreciation to my supportive

academic supervisor, Mr.Zolkarnain B. Marjom. His supervision and support that gave

me truly helps during the period of conducting my thesis. His never-ending supply of

valuable advice and guidance has enlightens me and deeply engraved in my mind.

Next, I would like to dedicate my thankfulness to the helpful of Mr. Saifudin, for his

enthusiastic support and supervision of the thesis revision. Im also happy to present my

gratefully acknowledge to Machinery laboratory technicians, who has been so warmth

and kind to provide sincere assistance and good cooperation during the training period.

Their co-operation is much indeed appreciated. In addition, I would like to convey thanks

to FKP lecturers, for their assistance, which really spends their time to teach me a lots of

knowledge regarding to the design development.

Last but not least, I would like to state my appreciation to the staff Faculty of

Manufacturing Engineering, FKP, my friend and colleagues for supporting me and

administration department for their help in the project . Thank you.

v

TABLE OF CONTENTS

Abstract.i

Abstrak ii

Dedication...............iii

Acknowledgements.iv

Table of Contents.v

List of Figures.ix

List of Tables..............xi

List of Sign and Symbolxii

1. INTRODUCTION...........................................................1

1.1 General Introduction....................................................1

1.2 Problem statement2

1.3 Objective..3

1.4 Scope of study..3

2. LITERATURE REVIEW...4

2.1 Introduction..4

2.2 Design for Manufacturing and Assembly (DFMA).5

2.3 Boothroyd Dewhurst DFA method..7

2.4 The Lucas DFA method...8

2.4.1 Functional Analysis..10

2.4.2 Handing Analysis..............10

2.4.3 Fitting Analysis.............12

2.5 The Guidelines of DFA..............13

2.5.1 A DFA guideline...13

2.5.2 Design Guidelines for Part Handling................14

vi

2.5.3 Design Guidelines for Insertion and Fastening.14

2.6 Types of Assembly15

2.7 DFA Process..16

2.8 Design for Manufacture Guidelines...17

2.8.1 General Principles of manufacturability...17

2.9 TeamSET...19

2.10 Application of DFMA in industry...21

2.10.1 Application of DFMA in aerospace industry.21

2.10.2 Application of DFMA in automotive industry...24

2.10.3 Application of DFMA in medical instrument industry..26

3. METHODOLOGY27

3.1 Method of Study27

3.2 TeamSET process flow..29

3.3 TeamSET database process....30

3.4 DFA analysis for existing product.34

3.4.1 Flow chart of existing product...............34

3.4.2 Flow chart of base part...............34

3.4.3 Flow chart of upper tunnel part..35

3.4.4 Flow chart of lower tunnel part..36

3.4.5 Detail drawing of existing product37

3.4.6 TeamSET analysis for existing product.37

vii

4. RESULT AND ANALYSIS...39

4.1 Introduction of analysis..39

4.2 Draw design using SolidWork software40

4.2.1 Detail drawing of first redesign.40

4.2.2 Detail drawing of second redesign.41

4.3 Analysis using TeamSET software42

4.3.1 DFA analysis for first redesign..42

4.3.1.1 Flow chart of first redesign44

4.3.1.2 Flow chart of upper tunnel part after first redesign...44

4.3.1.3 Flow chart of lower tunnel part after first redesign...45

4.3.1.4 Flow chart of base part after first redesign46

4.3.1.5 TeamSET analysis for first redesign..47

4.3.2 DFA analysis for second redesign.............48

4.3.2.1 Flow chart of second redesign...49

4.3.2.2 Flow chart of base structure part...49

4.3.2.3 Flow chart of cylinder blade part...50

4.3.2.4 Flow chart of tunnel part50

4.3.2.5 Flow chart of pulley system part51

4.3.2.6 TeamSET analysis for second redesign.51

4.4 Material and process selection.53

4.4.1 Shaft blade and shaft connector.53

4.4.2 Cylinder blade54

4.4.3 Base structure.55

4.4.4 Tunnel56

viii

5. DISCUSSION.57

5.1 Comparison of existing design with first and second redesign..57

5.2 Safeguards for prevent from mechanical hazards..59

6. CONCLUSION & FUTURE WORKS ...61

6.1 Conclusion.61

6.2 Future works..62

REFERENCES63

APPENDIX

A Gantt chart for PSM 1 & 2

B Detail drawing for redesign Grass Cutting Machine

ix

LIST OF FIGURE

1.1 The grass cutting machine 2

2.1 Flow chart of Lucas Hull method 9

2.2 Show DFA analysis 20

2.3 Show view of Longbow Apache Helicopter 23

2.4 Explode view of existing design of overhead luggage rack 24

2.5 Explode view of new design of overhead luggage rack 25

2.6 BagEasy III 26

3.1 Flow chart of Planning of the Study 28

3.2 The process flow in developing TeamSET database 29

3.3 The product maintaining projects, products and design scenarios 30

3.4 Product Breakdown Structure 31

3.5 Assembly Window 32

3.6 DFA analysis for assembly parts 33

3.7 A flow chart of existing product main part 34

3.8 A flow chart of base part 35

3.9 A flow chart of upper tunnel part 36

3.10 A flow chart of lower tunnel part 36

3.11 View of the existing product 37

3.12 TeamSET analysis for existing product 38

4.1 View of first redesign 40

4.2 View of second redesign 41

4.3 A flow chart of first redesign main part 44

4.4 A flow chart of upper tunnel part after redesign 45

4.5 A flow chart of lower tunnel part after redesign 45

x

4.6 A flow chart of base part 46

4.7 TeamSET analysis for improvement design 47

4.8 A flow chart of final design main part 49

4.9 A flow chart of base structure part 49

4.10 A flow chart of cylinder blade part 50

4.11 A flow chart of V-belt part 51

4.12 TeamSET analysis for second redesign 52

4.13 Drawing of shaft blade and shaft connector 53

4.14 View of cylinder blade 54

4.15 View of base structure 55

4.16 Cross section view of tunnel 56

4.17 Isometric view of tunnel 56

5.1 Part for accessories 59

5.2 View of the second redesign after installation accessories 60

6.1 Shows the comparison between existing product and second

redesign

61

xi

LIST OF TABLE

2.1 Lucas DFA method - Manual Handling Analysis 11

2.2 Lucas DFA method - Manual Fitting Analysis 12

2.3 Pilot's Instrument Panel Estimate Summary 23

4.1 Quantity List of a first redesign 43

4.2 Quantity List of a second redesign 48

5.1 Comparison of existing design with fisrt redesign 58

5.2 Comparison of existing design with second redesign 58

xii

LIST OF SIGN & SYMBOL

DFMA - Design for Manufacturing and Assembly

DFA - Design for Assembly

DFM - Design of Manufacturing

PDS - Product Design Specification

QFD - Quality Function Deployment

MA - Manufacturing Analysis

FMEA - Failure Modes and Effects Analysis

DTC - Design to Target Cost

ASF - Assembly Flowchart

IPD - Integrated Product Development

PEP - Engineering and Planning

IEFAB - Improved Extended Avionics Bay

CAD - Computer Aided Design

PBS - Product Breakdown Structure

1

CHAPTER 1

INTRODUCTION

1.1 General Introduction

Product lifecycle is being reduced drastically due to rapid changes in technology and

customers requirements. The global marketplace is changing so rapidly that industrialist

needs to adopt new strategies to respond customers requirement and in order to satisfy

the market needs more efficiently and quickly. Many companies especially in Japan,

USA and Europe have already started to implement techniques and tools that would

enable them to respond more quickly to consumers demand in delivering high quality

product at reasonable costs. The delay in time-to-market can be interpreted as a loss in

profit (Alan F & Jan Chal, 1994).

Currently, the implementation of Design for Manufacturing and Assembly (DFMA)

methodology are applied either manually or computer-aided. Most of the applied

interested in implementing DFMA are hindered by lack of clear guidelines or procedures

and no integration of isolated design and manufacturing teams. The advantages of the

integration are to decrease the number of part design and indirectly to reduce cost and

time. At the same time, it fulfills customers requirement. In this project, DFMA has been

applied in design and development the grass cutting machine. The design also must be

concerned to the requirement of the DFMA methodology in order to achieve high rank of

market selling.

2

1.2 Problem statement

In developing this project, there are several problems that need to be concerned and the

most suitable method that can be used to solve the problems is by applying the Design for

Manufacturing and Assembly (DFMA) methodology. In identifying of grass cutting

machine problems, the most important aspects that need to be concerned is the design of

the grass cutting machine. Some of the part grass cutting machine are being designed

quite complicated with accessories and need to be eliminated, in the same time reduced

the manufacturing cost and assembly time. Besides that, there are several parts had been

recognized that difficult to handle. So, with the application of Design for Manufacturing

and Assembly (DFMA) methodology is highly expected in solving these problems to suit

the customer requirements and convenient.

Figure 1.1: The grass cutting machine

3

1.3 Objective

The main objective of this project is using DFMA methodology to design the new grass

cutting machine and compare with the existing product. Beside that, other specific

objectives include:

a) to develop the grass cutting machine;

b) to design and analysis of original design;

c) to purpose grass cutting machine using DFMA method and TeamSET

software;

d) to determine the optimum manufacturing and assembly method for low

cost production with short production time.

1.4 Scope of study

a) Case study

A grass cutting machine has been selected as a case study for this project and had the

potential to be redesign by applying the Design for Manufacturing and Assembly

(DFMA) methodology. The tool selected for drawing the grass cutting machine is

SolidWork. User can easily generate drawing from a model. Photorealistic rendering

and animation that allow communicating how future products will look and perform

early in the development cycle.

b) Design for Assembly (DFA)

DFA is a systematic methodology that reduces manufacturing costs, total number of

parts in a product, and etcetera. For this project, the software called TeamSET is used

to analyze the design for existing product and redesign product.

4

CHAPTER 2

LITERATURE REVIEW

2.1 Introduction

To develop this project, the case study is to apply the Design for Manufacturing and

Assembly (DFMA). There are certain important DFMA tools that have been applied such

as Design for Assembly (DFA) and Design for Manufacture (DFM). These two important

DFMA tools are very useful especially to the industry. This chapter described about the

definition of Design for Manufacturing and Assembly (DFMA), Boothroyd Dewhurst

DFA method, the Lucas DFA method, the application of DFMA in industry and

application of engineering software called TeamSET.

5

2.2 Design for Manufacturing and Assembly (DFMA)

Design for Manufacturing and Assembly (DFMA) is a design philosophy used by

designers when a reduction in part counts, a reduction in assembly time, or a

simplification of subassemblies is desired. It can be used in any environment regardless

of how complex the part is or how technologically advanced this environment may be.

DFMA encourages concurrent engineering during product design so that the product

qualities reside with both designers and the other members of the developing team (D-

ESPAT, 2007).

According to Geoffrey Boothroyd, Professor of Industrial and Manufacturing at the

University of Rhode Island, the practices now known as Design for Assembly (DFA),

and Design for Manufacture (DFM) had their start in the late 1970's at the University of

Massachusetts. Of all the issues to consider, industry was most interested in Design for

Assembly. When developing a product, the maximum potential cannot be achieved

without considering all phases of the design and manufacturing cycle. DFMA meets this

demand by addressing key assembly factors before the product goes on to the prototype

stage. These key factors are the product appearance, type, the number of parts required in

the product, and the required assembly motions and processes (D-ESPAT, 2007).

The Term DFMA comes with the combination of DFA (Design for Assembly) and

DFM (Design of Manufacturing). The basic concept of it is that the design engineers

apply the DFMA paradigm or software to analyze the manufacturing and assembly

problems at the early design stage. By this means, all of considerations about the factors

that affect the final outputs occur as early as possible in the design cycle. The extra time

spent in the early design stage is much less the time that will be spent in the repeatedly

redesign. And meanwhile, the cost will be reduced. DFM is that by considering the

limitations related to the manufacturing at the early stage of the design; the design

engineer can make selection among the deferent materials, different technologies,

estimate the manufacturing time the product cost quantitatively and rapidly among the

different schemes. They compare all kinds of the design plans and technology plans, and

6

then the design team will make revises as soon as possible at the early stage of the design

period according this feedback information and determine the most satisfied design and

technology plan.

The three goals in DFM are:

1. Increase the quality of new produces during the development period, including

design, technology, manufacturing, service and so on.

2. Decrease the cost, including the cost of design, technology, manufacturing, delivery,

technical support, and discarding.

3. Shorten the developing cycle time, including the time of design, manufacturing

preparing, and repeatedly calculation.

DFA is considering and resolving the possible problems in the assembly process at the

early stage of the design which can make sure the part will be assembled with high speed,

low cost and productivity. DFA is a kind of design paradigm with which, the engineer

use all kinds of methods such as analyze, estimating, planning and simulating to consider

all the factors that will affect the assembly process during the whole design process;

revise the assembly constructions to satisfied the characteristics and functions of the final

products; and meanwhile, lower the cost as most as possible.

DFA is a kind of design method that can be used in two ways. The ways is a tool for

assembly analysis and a guide for assembly design. The former usage is that at the time

after the beginning of the product design, the engineer makes estimation of assembly

possibility by analyzing all the factors that can affect the assembly process, and give

suggestions. The second one is that collecting the knowledge and experience from the

assembly experts and recording them as design guides. By the help of these guides, the

engineer can choose the design plan and determine the product construction such as

under the guidance of those experts.

7

2.3 Boothroyd Dewhurst DFA method

In the history of DFMA, Ford and Chrysler use the DFM philosophy in their design and

manufacturing process of the weapons, tanks and other military products. Dr. Geoffrey

Boothroyd and Dr. Peter Dewhurst who founded the Boothroyd Dewhurst, Inc (BDI) in

1982 are the first persons doing the research job in this new technology at the beginning

in the early 1970s. Actually, the DFMA is a trademark of their company. They created

and developed the DFMA concept which is used in developing the products of their

company --- DFMA software system. Currently these programs are used to help the

design in almost all the industrial fields including circuit boards (G. Boothroyd & W.

Knight, 1993), with manual assembly, with robotic assembly, and with machining. They

also do a lot of work examining the economic justification of each design revision (G.

Causey, 1999).

They created and developed the DFMA concept which is used in developing the products

of their company such as DFMA software system. Currently these programs are used to

help the design in almost all the industrial fields including circuit boards, with manual

assembly, with robotic assembly, and with machining. They also do a lot of work

examining the economic justification of each design revision.

In generally, Boothroyd Dewhurst DFA method can determine the appropriate assembly

method and reducing the number of individual parts to be assembled. This method also

can ensure that the remaining parts are easy to assemble. The methods of assembly are

classified into three basic categories such as manual assembly, special-purpose transfer

machine assembly and robot assembly.

8

2.4 The Lucas DFA method

Although the Boothroyd-Dewhurst method is widely used, it is based on timing each of

the handling and insertion motions. Although tables of data are available, the most

accurate numbers are compiled through time studies in particular factories.

The basic construction of Lucas DFA is very similar to the DFA of BDI, it is the result of

the cooperation of Lucas Organization and the University of Hull in U.K. Now, the logic

of Lucas DFA has been integrated in the engineering analysis software TeamSet which

is the product of CCI Lucas DFA separates the product design process into three stages:

FcA (Function Analysis), HA (Handing Analysis) and FtA (Fitting Analysis). The

relations of these three stages are shown in Figure 2.1. Before the manufacturing and

assembly process, the PDS (Product Design Specification) occurs which change the

requirements of the customs into engineering specifications. After that, the design

engineers perform the design job according to this information. This is a kind of process

to change the engineering specifications into the real design and meanwhile, all the

requirements should be satisfied.

9

Figure 2.1: Lucas Hull method

10

2.4.1 Functional Analysis

In this analysis, the components of the product are reviewed only for their function. The

components are divided into two groups. Parts that belong to Group A are those that are

deemed to be essential to the product's function; Group B parts are those that are not

essential to the product's function. Group B functions include fastening, locating, and

etcetera. The functional efficiency of the design can be calculated as (Vincent Chan &

Filippo A. Salustri, 2005):

Ed = A/(A+B) x 100%

Where A is the number of essential components, and B is the number of non-essential

components. The design efficiency is used to pre-screen a design alternative before more

time is spent on it. This is different than the Boothroyd-Dewhurst method (which

assumes a design is already available). This analysis is intended to reduce the part count

in the product. Typically, a design efficiency of 60% is targeted for initial designs.

2.4.2 Handing Analysis

Similar to the Boothroyd-Dewhurst analysis, both the part handling and insertion times

are examined here. In the feeding analysis, the problems associated with the handling of

the part are scored using an appropriate table. For each part, the individual feeding index

is scored. Generally, the target index for a part is 1.5. If the index is greater than 1.5, the

part should be considered for redesign. Overall, all of the product's components should

meet a "feeding ratio" defined as (Vincent Chan & Filippo A. Salustri, 2005):

Handling Ratio = (Total Feeding Index) / (Number of Essential Components)

Total Handling Index = A+B+C+D

11

Where the total feeding index is the sum of all the indices of all the parts. The number of

essential components is the value A from the functional analysis. An ideal feeding ratio is

generally taken to be 2.5

Table 2.1: Lucas DFA method - Manual Handling Analysis

A. Size & Weight of Part One of the following

Very small - requires tools 1.5

Convenient - hands only 1

Large and/or heavy

requires more than 1 hand 1.5

Large and/or heavy

requires hoist or 2 people 3

B. Handling difficulties

All that apply

Delicate 0.4

Flexible 0.6

Sticky 0.5

Tangible 0.8

Severely nest 0.7

Sharp/Abrasive 0.3

Untouchable 0.5

Gripping problem / slippery 0.2

No handling difficulties 0

C. Orientation of Part

One of the following

Symmetrical, no orientation

required 0

End to end, easy to see 0.1

End to end, not visible 0.5

D. Rotational Orientation of Part


Rotational Symmetry 0

Rotational Orientation, easy to see 0.2

Rotational Orientation, hard to see 0.4

12

2.4.3 Fitting Analysis

The fitting analysis is calculated similarly to the feeding analysis. Again, a fitting index

of 1.5 is a goal value for each assembly. However, it should be noted that there is usually

greater variance in the fitting indices than in the feeding indices. Again, an overall fitting

ration of 2.5 is desired (Vincent Chan & Filippo A. Salustri, 2005).

Fitting Ratio = (Total Fitting Index) / (Number of Essential Components)

Total Fitting Index = A+B+C+D+E+F

Table 2.2: Lucas DFA method - Manual Fitting Analysis

A. Part Placing and Fastening


Self-holding orientation 1.0

Requires holding

Plus 1 of the following 2.0

Self-securing (i.e. snaps) 1.3

Screwing 4.0

Riveting 4.0

Bending 4.0

B. Process Direction


Straight line from above 0

Straight line not from above 0.1

Not a straight line 1.6

C. Insertion


Single 0

Multiple insertions 0.7

Simultaneous multiple insertions 1.2

E. Alignment


Easy to align 0

Difficult to align 0.7

F. Insertion Force


No resistance to insertion 0

Resistance to insertion 0.6

13

2.5 The Guidelines of DFA

The general guidelines of DFA that attempt to consolidate manufacturing knowledge and

present them to the designer in the form of simple rules to be followed when creating a

design. The process of assembly can be divided naturally into two separate areas,

handling assembly which means acquiring, orienting and moving the part. The secondly

area is insertion and fastening assembly which means mating a part to another part group

or group of part.

2.5.1 A DFA guideline

A DFA guideline is given below:

a) Aim for simplicity

Minimize part numbers, part variety, assembly surfaces; simplify assembly

sequences, component handling and insertion, for faster and more reliable assembly.

b) Standardize

Standardize on material usage, components, and aim for as much off-the-shelf

component as possible to allow improved inventory management, reduced tooling,

and the benefits of mass production even at low volumes.

c) Rationalize product design

Standardize on materials, components, and subassemblies throughout product

families to increase economies of scale and reduce equipment and tooling costs.

Employ modularity to allow variety to be introduced late in the assembly sequence

and simplify JIT production.

14

2.5.2 Design Guidelines for Part Handling

a) Design parts that have end-to-end symmetry and rotational symmetry about the

axis of insertion. If not try to design parts having the maximum possible

symmetry.

b) Design parts that, in those instances where the part cannot be made symmetric,

are obviously asymmetric

c) provide features that will prevent jamming of parts that tend to nest or stack when

stored in bulk

d) avoid features that will allow tangling of parts when stored in bulk

e) Avoid parts that stick together or are slippery, delicate, flexible, very small or

very large or that are hazardous to the handler.

2.5.3 Design Guidelines for Insertion and Fastening

a) Design with little or no resistance to insertion and provide chamfers to guide

insertion of two mating parts to provide generous clearance but not resulted for

parts to jam or hang-up during insertion

b) Standardize by using common parts, processes and methods across all models and

product lines to permit the use of higher volume processes that normally result in

lower product cost

c) Use pyramid assembly to provide for progressive assembly about one axis of

reference and it is best to assemble from above.

d) Try to avoid the necessity for holding parts down to maintain their orientation

during manipulation of the subassembly or during the placement of another part.

e) Design so that a part is located before it is released.

f) Try to follow the sequence of the mechanical fasteners and listed in order of

increasing manual assembly cost.

g) Avoid the need to reposition the partially completed assembly in the fixture.

15

2.6 Types of Assembly

There are three types of assembly, classified by the level of automation.

a) Manual assembly a human operator at a workstation reaches and grasps a part

from a tray, and then moves, orients and prepositions the part for insertion. The

operator then places the parts together and fastens them, often with a power tool.

The design Guidelines for Manual Assembly are:

i. Minimize the number of different parts use standard parts.

ii. Minimize the number of parts.

iii. Avoid or minimize part orientation during assembly

iv. Prefer easily handled parts that do not tangle or nest within one another.

b) Automatic assembly handling is accomplished with a parts feeder, like a

vibratory bowl, which in turn inserts the part. The design guidelines for

Automatic Assembly:

i. Reduce the number of different component by considering

ii. Use self-aligning and self-locating features

iii. Avoid screws/bolts.

c) Robotic assembly the handling and insertion of the part is done by a robot arm

under computer control. The cost of assembly is determined by the number of

parts in the assembly and the ease with which the parts can be handled and

inserted. Design can be have strong influence in both areas. Reduction in the

number of parts can be achieved by eliminating of parts example replacing screws

16

and washers with snap or press fit and by combining several parts into a single

component. Ease of handling and insertion is achieved by designing so that the

parts cannot become tangled or nested in each other and by designing with

symmetry in mind. Parts that do not require end-to-end orientation prior to

insertion as a screw does should be used if possible. Parts with complete

rotational symmetry around the axis of insertion like a washer are best.

2.7 DFA Process

Once parts are manufactured, they need to be assembled into subassemblies and products.

The assembly process consists of two operations, handling followed by insertion. The

DFA is a two step process (Shih-Wen Hsiao, 2001): -

a) Evaluate the assemblability of the individual parts whether they are easy to be

assembled or not.

b) Evaluate the theoretical minimum number pf parts that should be in the product.

In step 1 the designer uses some established rating system to evaluate each individual part

with respect to its:

Graspability: To check that the part is easy to be grasped or not during the period of

assembly.

Orientability: To check if the part is easy to be oriented or not when it is being

assembled

Transferability: To check whether the part is easy to be transferred to the work position

or not.

Insertability: To check if the part is easy to be inserted into the correct position or not

when it is being assembled.

Secureability: To check whether the part or the product is secure or not after the part has

been assembled.

17

2.8 Design for Manufacture Guidelines

Design for manufacture or 'Manufacturability' concerns the cost and difficulty of making

the product. At a simple level manufacturability, design for manufacture (DFM) at a part

level, involves detail such as ensuring that where a pin is to be assembled into a hole that

is only slightly larger in diameter, then it is much easier if the end of the pin or the entry

to the hole (or both) are chamfered or finished with a radius. This applies whether the

assembly is carried out manually or automatically. This is a fine tuning process carried

out once the product form has been decided. Indeed automatic assembly would be very

difficult / expensive if neither component of a close fitting pair was chamfered. At a more

complex level, product DFM tackles the more fundamental problem of deciding on the

product structure and form. Design for assembly (DFA) is an important part of this.

Some 'manufacturability' software is available, relating both to manufacture and to

assembly. This section starts with some simple but important principles of

manufacturability (David Grieve, 2003).

2.8.1 General Principles of manufacturability

a) Reducing the number of parts frequently reduces the weight of the product which

is advantageous. Eliminating the need for a separate housing or enclosure can be

beneficial. One method that has been successful in many cases is to replace a

fabricated sub - assembly, which may utilize many fasteners, with a single

casting. In some cases this has given weight savings as well as cost savings.

b) A robust design is one that has been optimised so that variations from the nominal

specification cause a minimum loss of quality. To determine these optimal values

will normally necessitate experimental work on a prototype.

c) The assembly of products made up from 4 to 8 modules with 4 to 12 parts per

module can usually be automated most readily. It is also helpful to maintain a

generic configuration as far as possible into the assembly process and install

specialist modules as late as possible.

18

d) Assembly from 1 direction is beneficial whether manual or automated assembly is

to be used. Generally assembling top down, along the z axis, like making a

sandwich, is the best solution.

e) Designing so only correct assembly is possible is useful where semi - skilled

labour is used and it is also desirable if there are safety considerations if the

product were to be incorrectly assembled. Manufacturers of mains powered

consumer electrical appliances frequently supply them with a flex having a

moulded on supply plug. This minimises the danger of the consumer incorrectly

wiring a plug and suffering an electric shock.

f) Using standard sizes will reduce costs directly and reduced delivery times will

indirectly give savings. This will also reduce the cost of repairs and maintenance.

g) Fasteners can add significantly to costs, frequently the cost of installation will

greatly exceed purchase cost. If fasteners must be used then minimise the sizes

and types. Small fasteners and parts should be avoided.

h) Mechanical adjustments add to the cost of fabrication and cause assembly, test

and reliability problems. The need for adjustments can often be negated by using

dowel pins, detents, notches or spring mounted components. If a designer

understands why an adjustment has been recommended, a way of eliminating or

reducing the need can often be found.

i) Wiring and other flexible components are difficult to handle during assembly.

The use of rigid or process applied gaskets, circuit boards rather than electric

wiring helps to minimize this problem.

j) Dimensioning from 1 datum simplifies gauging and minimizes errors in

tolerances. Dimensions should also be measured from points or surfaces on a

component, not points in space.

k) Using large radii is generally good practice for most processes, casting, forming

etc. as material flow is facilitated - and stress concentration is reduced. However

sharp corners are inevitable with some processes, eg 2 intersecting machined

surfaces and punch face - wall edge in a powdered metal component. There is no

cost advantage in preventing these sharp corners.

19

l) In simultaneous or concurrent engineering, personnel from functions other than

design are involved in the design process, including manufacturing specialists.

This enables all aspects of a design to be considered at an early stage.

m) This can be critical, particularly for closer tolerance parts because as tolerances

become tighter, the rise in manufacturing costs is increasingly steep.

2.9 TeamSET

TeamSET is a PC based software package which helps designers produce better products

at reduced cost and in shorter times. TeamSET is a PC based software package based

integrated set of applications that support design team working and encourages a

multidisciplinary culture. The TeamSET concurrent engineering software toolkit

includes Quality Function Deployment (QFD) to help to understand the customers

wants, and develop the product specification, Design for Assembly (DFA) to simplify

product structure and optimise component handling and assembly, Manufacturing

Analysis (MA) to select the most appropriate materials and processes for component

manufacture, Failure Modes and Effects Analysis (FMEA) to ensure the design is robust,

Design to Target Cost (DTC) to monitor product costs throughout the design process, and

Controlled Concept Convergence to select the best options. The result from the tool kit

will helps product design teams to produce better products at lower cost and in a shorter

time (TeamSet, 2008). DFA analysis is carried out on a graphical chart as shown in

Figure 2.2

20

The benefits of TeamSET are:

a) The provision of such a focus allows design team to explore and compare design or

re-design options quickly and with minimum effort.

b) Will allow user addressed such problems as time to market, quality, reliability and

cost by ensuring that the design to which user are committing is simple to

manufacture and assemble has a minimum of non-essential parts, keeps tooling costs

down and will meet customer needs.

c) Work from previous products, assemblies and part analysis can be re-used in later

design activities negating the need to start from scratch each time.

d) This will not only shorten analysis times but also enable user to capitalize on the

benefits that accrue from standardization, consistency and predictability.

Figure 2.2: DFA analysis

21

Teamset is a result of the collaboration between lucas and the university of Hull. It does

not use cost analysis, and in this respect differs from the Hitachi and Boothroyd-

Dewhurst method. The method involves the assigning and summing of penalty factors

associated wih potential design problems, similar to the Hotachi method but with the

inclusion of handling as well as insertion. These are denoed in visual flow called an

Assembly Flowchart (ASF). The TeamSet database contains a number of projects, each

of whichwill contain a number of associated products. Each of these will have a number

of different design scenarios, which in turn well be broken down in a hierarchy of

elements a product breakdown structure. Each elements of this structure can be

associated with a particular assembly of parts for which detailed information is stored

(Anonymous, 1998).

2.10 Application of DFMA in industry

2.10.1 Application of DFMA in aerospace industry

This study examines the effectiveness of Design for Manufacturing and Assembly

(DFMA) methodology used by the design, manufacturing, quality, and supporting

engineers for the development of the Longbow Apache Helicopter. Data were obtained

through the Integrated Product Development (IPD) team for several redesigned areas of

the Longbow prototype Helicopter Crew Station. Results of the study show that DFMA

can be an effective approach, as indicated by a significant cost and weight savings (D-

ESPAT, 2007).

During the years of 1994 and 1995, MDHS redesigned and optimized one of the six

Longbow prototype helicopters. An Integrated Product Development (IPD) team was

formed to conduct this redesign. The IPD team is a concurrent engineering team where

representatives of several organizations such as engineering, manufacturing,

procurement, suppliers, product support, quality, and others, work together to develop a

product design. This design is then brought into production in a short period of time

without the budget and lengthy schedule usually encountered by other organizations

22

without a team concept in place. Six helicopters were completed in the prototype phase

and the experience obtained from this phase was applied to the Longbow Initiatives

Project. During this project, Design and Producibility Engineering and Planning (PEP),

which was developed and implemented with the purpose of improving the previous

prototype aircraft configuration used DFMA as an aid to accomplish that established

objective. DFMA was applied to a limited number of parts within the crew station, and

the Improved Extended Avionics Bay (IEFAB) of the Longbow Apache Helicopter. Data

were gathered and recorded by the IPD Team and compared to the baseline prototype

helicopters which were designed without using DFMA (D-ESPAT, 2007).

Each DFMA case study was conducted by redesigning existing assemblies. The IPD team

met and analyzed its requirements, including material, function, and location of parts.

Once a preliminary design was done, the team studied it in order to reduce the part count,

weight, and assembly time. Data was obtained from each IPD team member that was

involved in the DFMA process. Their estimates, tables and schedules were analyzed. All

data that could be found relating to DFMA applications on the Longbow Apache

Program including: producibility analyses, design concept descriptions and lists, weight

data analysis, schedules based on the design and manufacturing plans, cost estimates, and

detailed DFMA plans on at least four assemblies, were used to assess the impact of

DFMA. Data were collected and summarized as they were made available by the IPD

Team (D-ESPAT, 2007).

Collected data were loaded into the Boothroyd Dewhurst Inc.'s (BDI) DFA 7.1a software.

This software analyzes the design, manufacturing, assembly process, and materials used.

It then summarizes and provides recommendations on how to improve the design using

DFMA philosophy (D-ESPAT, 2007).

The first assembly examined is the Pilot's Instrument Panel which is comprised of a

combination of sheet metal angles and extruded stiffeners. The panel itself is attached to

an existing airframe structure with rivets. It consists of 74 parts with a weight of 3.00

Kilograms. The fabrication time for this instrument panel is 305 hours. This panel also

23

requires a final assembly tooling fixture in addition to tooling needed to form all brackets

and angles. Utilizing DFMA in conjunction with the IPD Team concept and availability

of HSDM, resulted in the redesign of the pilot's instrument panel, into only 9 parts (D-

ESPAT, 2007).

Subsequent analysis yielded data indicating that the fabrication time could be reduced to

20 hours. The total manufacturing and assembly time would be reduced from 697 hours

to 181 hours, weight reduction would be to 2.74 Kilograms, and the total cost was

reduced by 74%. The pilot's instrument panel DFMA concept is shown, and Table 1

provides a summary of the estimated comparison for the Pilot's Instrument Panel (D-

ESPAT, 2007).

Table 2.3: Pilot's Instrument Panel Estimate Summary

Figure 2.3: Show view of Longbow Apache Helicopter

Presenet Instument

Panels

DFMA Proposed

Instrument Panels

Part Count 74 pieces 9 pieces

Fabrication Time 305 Hours 20 Hours

Assembly/Installation

Time 149/153 Hour 8/153 Hour

Total Time 697 Hours 181 Hours

Weight 3.00 Kilograms 2.78 Kilograms

Cost 74% Reduction

24

2.10.2 Application of DFMA in automotive industry

This study examines the effectiveness of Design for Manufacturing and Assembly

(DFMA) methodology used by the design, manufacturing, quality, and supporting

engineers for the development of the overhead luggage rack. The objective of this study

examines are reduce product cost, reduce assembly problems and improve function. The

existing design consisted of cast ribs, sheet material and numerous fasteners. At 43ft long

it is installed through the windscreen and then held in position while fasteners are

inserted horizontally and vertically to secure it. Subsequent replacement of the centre

roof trim was not possible (TeamSet, 2008b). Figure 2.4 show the explode view of

existing design.

Figure 2.4: Explode view of existing design of overhead luggage rack

25

The new design uses 3 full length interlocking extrusions and a minimum of fasteners.

During installation the lower edge is hooked onto the body side supporting the main

weight of the assembly, it is then rotated upward into position and secured to the roof.

The centre roof trim can now be removed without disturbing the rack. A wiring harness

previously held by p clips and prone to damage by screws and screw drivers, is now

safely routed through a channel in one of the extrusions and retained by foam rubber

blocks (TeamSet, 2008b). The result achieve from this study examines is part reduction

from 4730 to 2210 and improvement installation time is 62 hours down to 17 hours.

Figure 2.5 show the explode view of new design.

Figure 2.5: Explode view of new design of overhead luggage rack

26

2.10.3 Application of DFMA in medical instrument industry

The BagEasy III is a manual resuscitator designed for single patient use (to be used

multiple times on a single patient) by medical personnel in emergency rooms,

ambulances and other treatment locations. A design team was founded and the goal of the

team was to finish the design with a concept what would meet the product requirement

and meanwhile, improve the manufacturability of the product. They used Boothroyd-

Dewhurst DFMA as the framework during the whole design process. Throughout the

whole design process, every member of the team shared the ideals with each other. They

communicated every day and the team meeting happened anytime as needed. This

resulted breaking down the walls between functions and achieving parallel design

method which focused the team on the object. Every member knew their product and

what the product was going to be. Supplier took part in the team activities and answered

the questions from the designer on how the parts could be produced. The feedback comes

so quickly instead of long time waiting as usual. After the concept design finished,

models generated in CAD was used for analysis. As details of the design created, the

concept was turned into real-word models. The team members met the supplier at this

time, reviewed the part design and developed a better one. The results of these efforts are

that the new product is greatly simplified; the improvement of assembly is 84%, of

assembly cost is 74% (Xiaofan Xie, 2003). Figure 2.6 show the picture of BagEasy III.

Figure 2.6: BagEasy III

27

CHAPTER 3

METHODOLOGY

3.1 Method of Study

In this section, the explanations is more on the project development which is based on the

chart to ensure the procedure and the steps of the project will be done properly in the

appropriate time which had been planed before. The methodology of the project starts

with the introduction of product to be studied and then some literature review on the

design for manufacturing and assembly method, application of DFMA and techniques for

case study. The data for literature review was founded from journals, related reference

books from library, and also internet. After that, the procedure goes on gaining the

information from the existing product. The method used for collecting data was from the

reassemble the existing product. These data were used to apply analysis using TeamSET

software. DFA analysis will be applied to the existing product design. The purpose of this

analysis is to verify the design efficiency of existing product including assembly process,

parts included and etcetera. Then from the result achieved, the result will be analyzed in

order to get the best design for redesign purposed. Solidwork software will be used in

order to make a drawing of redesign the existing product. Figure 3.1 shows the flow chart

of the planning of the study.

28

Figure 3.1: Flow chart of Planning of the Study

Do Literatures

Understanding the Title, Problem Statement & Objectives

Start

Journal/

Reports

Existing Product

Analysis

Existing Product Specification

Discussion

Satisfy?

NO

YES

Existing

Product

Observation

Problems

Redesign Process

Technical Redesign Analysis

Transfer the Redesign into SolidWork

Conclusion & Future Work

Final Report

End

29

3.2 TeamSET process flow

The TeamSET database contains a number of projects, each of which will contain a

number of associated products. Each of these will have a number of different design

scenarios, which in turn will be broken down in a hierarchy of elements which is a

product breakdown structure. Each element of this structure can be associated with a

particular assembly of parts for which detailed information is stored. Figure 3.2 showed

the process flow to develop the TeamSET database.

Figure 3.2: The process flow in developing TeamSET database

Projects

Products

Scenarios

Product breakdown

structure

Assemblies

Database

30

3.3 TeamSET database process

a) Step 1

The first process is creating and maintaining projects, products and design scenarios

for product to be analyzed as show in Figure 3.3.

Figure 3.3: The product maintaining projects, products and design scenarios.

A product represents the

final deliverable item

A project allows to group

together products that

might be part of an overall

product line.

A scenario represents

alternative way of

manufacturing product and is

related to one PBS. As

comparison for electing best

31

b) Step 2

Creating the Product Breakdown Structure (PBS) for products as shown in figure 3.4.

The PBS allows to:

i. Specify the number of times (quantity) that a particular element occur.

ii. Associate each element with an assembly.

Figure 3.4: Product Breakdown Structure

32

c) Step 3

An assembly may be formed exclusively from a collection of simple parts or many

contain more complex parts as shown in Figure 3.5.

Figure 3.5: Assembly Window

33

d) Step 4

Create a main work window to perform a DFA analysis on assembly parts as shown

in Figure 3.6.

Figure 3.6: DFA analysis for assembly parts.

Part list

HA to determine the difficulty of

handling and orientation

Assembly

flowchart

the final

deliverable

item

FA analysis to determine

whether A part or B part

34

3.4 DFA analysis for existing product

3.4.1 Flow chart of existing product

Existing product can be divided to three main parts as follow: -

a) base part

b) Upper tunnel part

c) Lower tunnel part

Figure 3.7: A flow chart of existing product main part

3.4.2 Flow chart of base part

Base part had eleven sub-parts as follow: -

a) nut D12mm

b) bolt 17x76

c) washer D22mm

d) bearing

e) bearing holder

f) v-belt

g) pulley

h) motor

i) plug

j) cable

k) screw

Existing product

Upper tunnel

part

Base part Lower tunnel

part

35

Figure 3.8: A flow chart of base part

3.4.3 Flow chart of upper tunnel part

Upper tunnel part had twelve sub-parts as follow: -

a) Nut D12mm

b) Nut D10mm

c) Bolt 17x36

d) Bolt 17x76

e) Washer D22mm

f) Washer D13mm

g) Safety guide

h) Rod

i) Blade

j) Allenkey screw

k) Bearing

l) Bearing holder

Nut

Base part

Bolt

Washer

Cable

Screw

Bearing

holder

Motor

V-belt

Bearing

Pulley

Plug

36

Figure 3.9: A flow chart of upper tunnel part

3.4.4 Flow chart of lower tunnel part

Lower tunnel part had three sub-parts as follow: -

a) nut D 12mm

b) bolt 17x36

c) washer D22mm

Figure 3.10: A flow chart of lower tunnel part

Nut

D10m

m

Upper tunnel

part

Bolt17x3

6

Washer

D22mm

Blade Allenkey

screw

Bearing

holder

Rod Safety

guide

Bearing

Bolt17x76

Nut

D12mm

Lower tunnel part

Nut D12mm Washer

D22mm Bolt 17x36

37

3.5 Detail drawing of existing product

TOP VIEW SIDE VIEW

FRONT VIEW ISOMETRIC VIEW

Figure 3.11: View of the existing product

3.6 TeamSET analysis for existing product

Figure 3.12 shows the analysis of existing product using TeamSET software. The result

shows about 120 parts that contains in this design and for A part is about 21 parts. The

design efficiency for this design is 18%. The handling ratio is 7.6 and for assembly ratio

is about 4.8. According to this result, this design needs to be redesigned because it does

not achieve the criteria in Lucas Hull theory.

38

TeamSET - Assembly ReportGrass Cutting Machine

1-Jan-2008 - 9:59

Company : UTEM

Assembly : original

Version : 1

Parts : 120

A Parts : 21

Design Efficiency: 18%

Handling score: 160.2

Handling ratio : 7.6

Handling limit : 1.5

Assembly score: 100.0

Assembly ratio : 4.8

Assembly limit : 1.5

Work Holder Insertion Remove Tool / DisassemblySecondary Op

Insert Tool / Reassembly Wrong Way Round

No. Part Name Qty. FA A's B's MA Hand. Assembly Flow

1 G.C.M

2 upper tunnel

3 7 A 1 6 - 1.1 nut 2.1

4 14 B 0 14 - 1.3 washer 2.1 2.1

5 7 A 1 6 - 1.1 bolt 4.1

6 1 A 1 0 - 1.1 safety guard 1.1

7 rod

8 8 A 1 7 - 1.1 allenkey screw 4.1

9 8 A 1 7 - 1.1 nut 2.1 2.1

10 16 B 0 16 - 1.3 washer 2.1 2.1

11 2 A 1 1 - 1.6 blade 2.1

12 1 1.1 rod 14.6

1.1

13 bearing

14 2 A 1 1 - 1.1 bolt 4.0

15 2 A 1 1 - 1.1 nut 2.0 2.0

16 4 B 0 4 - 1.3 washer 2.0 2.0

17 1 A 1 0 - 1.3 bearing holder 1.0

18 1 1.0 bearing 13.0

1.0

19 1 1.7 upper tunnel 41.2

2.1

20 lower tunnel

21 4 A 1 3 - 1.1 bolt 4.0

22 4 A 1 3 - 1.1 nut 2.0 2.0

23 8 B 0 8 - 1.3 washer 2.0 2.0

24 1 1.7 lower tunnel 12.0

1.0

25 base

26 bearing


28 2 A 1 1 - 1.1 bolt 4.0

29 2 A 1 1 - 1.1 nut 2.0 2.0

30 4 B 0 4 - 1.3 washer 2.0 2.0

31 1 1.0 bearing 13.0

1.0

32 motor

33 4 A 1 3 - 1.1 bolt 4.1

34 4 A 1 3 - 1.1 nut 2.1 2.1

35 8 B 0 8 - 1.3 washer 2.1 2.1

36 1 A 1 0 - 1.0 plug 1.0

37 1 A 1 0 - 1.6 cabel 1.0

38 1 1.7 motor 14.5

2.1

39 1 A 1 0 - 1.6 v-belt 1.0

40 pulley

41 2 A 1 1 - 1.1 screw 4.0

42 2 1.2 pulley 8.0

2.1

43 1 1.5 base 41.7

1.0

44 1 3.0G.C.M 99.0

1.0

Figure 3.12: TeamSET analysis for existing product

39

CHAPTER 4

RESULT AND ANALYSIS

4.1 Introduction of analysis

This chapter focused on the analysis based on product selected that is grass cutting

machine. The analysis will be done by using the approach of Design for Manufacturing

and Assembly (DFMA) methodology. DFMA is a systematic approach that reduced

manufacturing costs by reducing the total number of individual parts in a product for ease

of handling and insertion. To fulfill this analysis, TeamSET software had been selected

by Lucas Hull approached. The analysis will concentrate based on the design efficiency,

handling ratio and fitting ratio for existing product and also for redesign product.

SolidWork is used for draw the detail drawing of design.

40

4.2 Draw design using SolidWork software

SolidWork is the one of the 3D design software that can find in the market. In addition, in

SolidWork 3D models and 2D drawings communicate. Users can easily generate

drawings from a model. And when a change in either a drawing or model occurs, all

related drawings and models update automatically. Working in SolidWorks went very

quickly and gave a lot of satisfaction. Photorealistic renderings and animations that allow

communicating how future products will look and perform early in the development

cycle.

4.2.1 Detail drawing of first redesign

TOP VIEW SIDE VIEW


Figure 4.1: View of first redesign

41

4.2.2 Detail drawing of second redesign

TOP VIEW SIDE VIEW


Figure 4.2: View of second redesign

42

4.3 Analysis using TeamSET software

TeamSET is PC based software that functionally to help designer to do redesign product

and it base of Lucas Hull DFA method. This method has been explained at chapter two.

Five contents at this software that related to DFA analysis is such as functional analysis,

manufacturing analysis, handling analysis, fitting analysis and assembly analysis. By

using this software, three designs will be analyze such as existing design, first redesign

and second redesign. Before start perform any analysis using this software, the first step

need to taken is create the flow chart for each design. Then the analysis can carried out by

refer to the flow chart.

4.3.1 DFA analysis for first redesign

The list below showed the part after redesign existing product. A few parts from the

existing product had been eliminate or combined with other parts. The list of the first

redesign is illustrated in table 4.1.

43

Table 4.1: Quantity List of a first redesign

Ref

No

Description

Quantity

1

2

3

4

5

6

7

8

9

10

11

12

13

14

15

16

17

18

19

20

21

Upper tunnel

Lower tunnel

Lock

Safety guide

Rod

Bolt 17x76

Allenkey screw

Nut D10mm

Nut D 12mm

Washer D22mm

Washer D13mm

Blade

Bearing D80mm

Bearing holder

Base

Motor

Plug

Cable

v-belt

pulley

screw

1

1

2

1

1

8

4

4

12

12

8

1

2

2

1

1

1

1

1

2

2

Total parts 69

44

4.3.1.1 Flow chart of first redesign

First redesign can be divided to three main parts as follow: -

a) Upper tunnel part

b) Lower tunnel part

c) base part

Figure 4.3: A flow chart of first redesign main part

4.3.1.2 Flow chart of upper tunnel part after first redesign

Upper tunnel part had eleven sub-parts as follow: -

a) Nut D10mm

b) Nut D12mm

c) Bolt 17x76mm

d) Washer D13mm

e) Washer D22mm

f) lock

g) Safety guide

h) Rod

i) Blade

j) Allenkey screw

k) Bearing

l) Bearing holder

First redesign

Upper tunnel

part

Base part Lower tunnel

part

45

Figure 4.4: A flow chart of upper tunnel part after redesign

4.3.1.3 Flow chart of lower tunnel part after first redesign

Lower tunnel part had two sub-parts as follow: -

a) nut

b) bolt 17x

Figure 4.5: A flow chart of lower tunnel part after redesign

Lower tunnel part

Nut Bolt

Nut

D12mm

Upper tunnel

part

Bolt

17x76

Washer

D13mm

Blade Allenkey

screw

Bearing

holder

Rod

Safety

guide

Bearing

Nut

D10mm

Lock

Washer

D22mm

46

4.3.1.4 Flow chart of base part after first redesign

Base part had eleven sub-parts as follow: -

a) Nut D12mm

b) bolt 17x76mm

c) washer D22mm

d) bearing

e) bearing holder

f) v-belt

g) pulley

h) motor

i) plug

j) cable

k) screw

Figure 4.6: A flow chart of base part

Nut

D12mm

Base part

Bolt

17x76mm

Washer

D22mm

Cable

Screw

Bearing

holder

Motor

V-belt

Bearing

Pulley

Plug

47

4.3.1.5 TeamSET analysis for first redesign


1-Jan-2008 - 10:17

Company : UTEM

Assembly: redesign

Version : 1

Parts : 69

A Parts : 20











1 G.C.M

2 upper tunnel

3 2 A 1 1 - 1.0 lock 1.0

4 1 A 1 0 - 1.1 safety guard 1.1

5 rod

6 4 A 1 3 - 1.1 allenkey screw 4.1

7 4 A 1 3 - 1.1 nut D10mm 2.1 2.1

8 8 B 0 8 - 1.3 washer D13mm 2.1 2.1

9 1 A 1 0 - 1.6 blade 2.1

10 1 1.1 rod 14.6

1.1

11 bearing

12 2 A 1 1 - 1.1 bolt 17x76mm 4.0

13 2 A 1 1 - 1.1 nut D12mm 2.0 2.0

14 4 B 0 4 - 1.3 washer D22mm 2.0 2.0


16 1 1.0 bearing 13.0

1.0

17 1 1.7 upper tunnel 31.8

2.1

18 lower tunnel

19 4 A 1 3 - 1.1 bolt 17x76mm 4.0

20 4 A 1 3 - 1.1 nut D12mm 2.0 2.0

21 1 1.7 lower tunnel 8.0

?

22 base

23 bearing


25 2 A 1 1 - 1.1 bolt 17x76mm 4.0

26 2 A 1 1 - 1.1 nut D12mm 2.0 2.0

27 4 B 0 4 - 1.3 washer 2.0 2.0

28 1 1.0 bearing 13.0

1.0

29 motor

30 4 A 1 3 - 1.1 bolt 17x76mm 4.1

31 4 A 1 3 - 1.1 nut D12mm 2.1 2.1

32 4 B 0 4 - 1.3 washer 2.1 2.1

33 1 A 1 0 - 1.0 plug 1.0

34 1 A 1 0 - 1.6 cabel 1.0

35 1 1.7 motor 14.5

2.1

36 1 A 1 0 - 1.6 v-belt 1.0

37 pulley

38 2 A 1 1 - 1.1 screw 4.0

39 2 1.2 pulley 8.0

2.1

40 1 1.5 base 41.7

1.0

41 1 3.0G.C.M 84.6

1.0

Figure 4.7: TeamSET analysis for improvement design

48

Figure 4.7 shows the analysis of first redesign using TeamSET software. The result



is about 4.3. According to this result, this design needs to be redesigned because it does

not achieve the criteria in Lucas Hull theory.

4.3.2 DFA analysis for second redesign

The list below showed the part after redesign again. A few parts from the improvement

design had been eliminate or combined with other parts. The list of the final design is

illustrated in table 4.2:

Table 4.2: Quantity List of a second redesign

Ref No

Description

Quantity

1

2

3

4

5

6

7

8

9

10

11

12

13

14

15

16

17

18

Motor

Bolt 17x76

Bolt 17x25

Base structure

Bearing D20mm

Bearing D24mm

Bush D83mm

Bush D60mm

Shaft blade

Screw 8x12mm

Screw 8x18mm

Cylinder blade

Tunnel

Pulley D50mm

Pulley D88mm

Shaft connector

Key

V-belt

1

4

2

1

1

1

1

1

1

2

2

1

1

1

1

1

1

1

Total parts 24

49

4.3.2.1 Flow chart of second redesign

Second redesign can be divided to four main parts as follow: -

a) Base structure part

b) Cylinder blade part

c) Tunnel part

d) V-belt part

Figure 4.8: A flow chart of final design main part

4.3.2.2 Flow chart of base structure part

Base structure part had two sub-parts as follow: -

a) Motor system

b) Bolt 17x76mm

Figure 4.9: A flow chart of base structure part

Base structure part

Motor system Bolt 17x76mm

Second redesign

Base structure

part

Pulley

system part

Cylinder blade

part Tunnel part

50

4.3.2.3 Flow chart of cylinder blade part

Cylinder blade part had six sub-parts as follow: -

a) Bearing D20mm

b) Bearing D24mm

c) Bush D83mm

d) Bush D60mm

e) Shaft blade

f) Screw 8x12mm

Figure 4.10: A flow chart of cylinder blade part

4.3.2.4 Flow chart of tunnel part

Tunnel part only had one sub-part. The sub-part is bolt 17x25mm. The only main part

that had more than one part needs to make flow chart. That mean, no need to make flow

chart for this part.

Shaft

blade

Cylinder blade

part

Bearing

D20mm

Bearing

D24mm

Screw

8x12mm

Bush

D83mm

Bush

D60mm

51

4.3.2.5 Flow chart of pulley system part

V-belt part had five sub-parts as follow: -

a) Pulley D50mm

b) Pulley D88mm

c) Shaft connector

d) Screw 8x18mm

e) Key

Figure 4.11: A flow chart of V-belt part

4.3.2.6 TeamSET analysis for second redesign

Figure 4.12 shows the analysis of second redesign using TeamSET software. The result



is about 2.4. According to this result, this design no needs to be redesigned because it

achieves the criteria in Lucas Hull theory. A good design is considered when design

efficiency over 60%, handling ratio less than 2.5 and assembly ratio less than 2.5.

Shaft

connector

V-belt part

Pulley

D50mm

Screw

8x18mm

Key Pulley

D88mm

52


27-Mar-2008 - 1:09

Company : DEFAULT

Assembly: final design

Version : 1

Parts : 24

A Parts : 18











1 base ass

2 1 A 1 0 - 1.5 motor 1.0 1.0

3 4 A 1 3 - 1.1 bolt 17x75 4.0

4 1 A 1 0 - 3.0 base 1.51.0

5 1 3.0base ass 8.5

1.0

6 cylinder blade ass

7 1 A 1 0 - 1.0 bearing D20mm 1.7 1.1

8 1 A 1 0 - 1.0 bearing D24mm 1.7

9 1 A 1 0 - 1.0 bush D83mm 2.4

10 1 A 1 0 - 1.0 bush D60mm 2.4

11 1 A 1 0 - 1.5 shaft blade 1.1

12 2 A 1 1 - 1.1 screw 8x12mm 4.0

13 1 A 1 0 - 1.5 cylider blade 1.1

14 1 1.5cylinder blade ass 15.5

1.0

15 tunnel ass

16 1 A 1 0 - 1.5 tunnel 1.0

17 2 A 1 1 - 1.1 bolt 17x25 4.1

18 1 1.5tunnel ass 5.1

1.0

19 V-belt ass

20 1 A 1 0 - 1.1 pulley D50mm 1.1

21 1 A 1 0 - 1.1 pulley D88mm 1.1

22 1 A 1 0 - 1.5 shaft connector 1.1

23 2 A 1 1 - 1.1 screw 8x18mm 4.0

24 1 A 1 0 - 1.0 key 1.7

25 1 A 1 0 - 1.6 v-belt 1.8

26 1 1.0V-belt ass 10.8

1.1

Figure 4.12: TeamSET analysis for second redesign

53

4.4 Material and process selection

Selection of materials for the part machine is very important. Only part that had been

redesign need to identify such as follow:-

a) Shaft connector

b) Shaft blade

c) Cylinder blade

d) Base structure

e) Tunnel

4.4.1 Shaft blade and shaft connector

A shaft blade is functionally to rotate the cylinder blade and shaft connector used to

connect the shaft blade with pulley. Material that used for shaft blade and shaft connector

is mild steel cylinder. Diameter of the mild steel cylinder is 35mm x 500mm.

manufacturing process that involved is turning process.

Shaft blade shaft connector

Figure 4.13: drawing of shaft blade and shaft connector

\

54

4.4.2 Cylinder blade

A cylinder blade is a mechanical device for cut the grass. Its will assemble with shaft

blade. Material that used for cylinder blade is mild steel plate with thickness 3mm and

cylinder hollow steel with diameter 34mm. The first machining process involved in this

fabrication is cutting material by using speed cutter machine and laser cutting machine.

Speed cutting machine used to cut the cylinder hollow steel and laser cutting machine is

used to cut the mild steel plate. After cutting process complete and final step is to

welding process by using metal inert gas welding machine (MIG).

FRONT VIEW SIDE VIEW

ISOMETRIC VIEW

Figure 4.14: View of cylinder blade

55

4.4.3 Base structure

Base structure is purpose to support motor, tunnel and cylinder blade. Base structure can

be divided into two sections such as mounting and structure. The processes that involved

are cutting process, milling process, drilling process and welding process. Material that

used for mounting is mild steel plate with thickness 20mm and for structure used angle

iron steel with thickness 3 mm. Two type of machines that involved in cutting process

which are laser cutting machine and speed cutting machine. Miling machine is a machine

tool used for the complex shaping of metal and other solid materials. Its basic form is that

of a rotating cutter or end mill which rotates about the spindle axis (similar to a drill), and

a movable table to which the work piece is affixed.Milling process is used to make

counter bore at the mounting. Diameter of counter bore is 66mm for left side and 86mm

for the right side. Welding process is for joint all part together by using metal inert gas

welding machine (MIG). Last process that involved is drilling process by using drilling

machine.

Figure 4.15: View of base structure

Mounting

56

4.4.4 Tunnel

Tunnel is purpose to cover cylinder blade and mounting. Material that used for fabricate

tunnel is mild steel plate with thickness 3mm. The process that involved in producing this

part is cutting process, bending process, welding process and drilling process. Cutting

process is for cut material according to dimension specification. The machine that

involved in this process is laser cutting. After cutting process had been done the next

process is the bending process. This process used bending machine to fabricate the part.

Figure 4.16: cross section view of tunnel

Figure 4.17: isometric view of tunnel

57

CHAPTER 5

DISCUSSION

5.1 Comparison of existing design with first and second redesign

The TeamSET approached had been used thoroughly in this project. With TeamSET

software analysis, the result was very useful especially for manufacturer to study about

their products. Beside, the software also managed to detect the problem or unimportant

part which can be eliminated. According to the table 5.1 and table 5.2, the second design

more improve if compared with first design. The part reduction for second redesign is

80% improvement. This mean part reduction for second redesign is higher than part

reduction for first design. Handling ratio is the total handling score divided by the count

of A parts. The handling ratio for existing design is 7.6. In the other hand, handling

ratio for existing design not achieve the criteria in Lucas hull theory so its need to

redesign. After first redesign, the handling ratio still not achieves criteria in Lucas hull

theory but the handling ratio reduction improves to 39.47%. First redesign needs to

redesign again until its achieve all criteria in Lucas hull theory. After second redesign,

the handling ratio is 2.1 and its less than 2.5. Second redesign is considering as a good

design. Handling ratio improvement for second redesign is 72.37% and assembly ratio

improvement for second redesign is 50%.

58

Table 5.1: Comparison of existing design with fisrt redesign

Existing design First redesign Improvement %

Total parts 120 69 42.5%

Handling ratio 7.6 4.6 39.47%

Assembly ratio 4.8 4.3 10.41%

Design efficiency 18% 29% 11%

Table 5.2: Comparison of existing design with second redesign

Existing design second redesign Improvement %

Total parts 120 24 80%

Handling ratio 7.6 2.1 72.37%

Assembly ratio 4.8 2.4 50%

Design efficiency 18% 75% 57%

According to the analysis that has been done, the analysis show that second redesign is

the best design because this design achieve all the criteria in Lucas hull theory. The

design efficiency for second redesign is over than 60%. The handling ratio and assembly

ratio for second redesign is less than 2.5. If the design not achieves one of these three

criteria the design should be reconsidered before continuing the following analysis.

59

5.2 Safeguards for prevent from mechanical hazards

The workplace with moving machine parts can be a very dangerous place for users.

Various mechanical hazards need a good of machine safeguarding. In ideal case any

mechanical motion that threatens a users safety should not remain unguarded. Crushed

hands and arms, severed fingers, blindness are among the list of possible machinery-

related injuries. Safeguards are thus essential for protecting users from uncalled-for and

preventable injuries. The safeguards for the redesign product are such as:

a) Funnel

b) Rubber protector

c) Cover belting system.

FUNNEL RUBBER PROTECTOR

COVER BELTING SYSTEM

Figure 5.1: Part for accessories

60

TOP VIEW ISOMETRIC VIEW

FRONT VIEW SIDE VIEW

Figure 5.2: View of the second redesign after installation accessories

61

CHAPTER 6

CONCLUSION & FUTURE WORKS

6.1 Conclusion

As a conclusion, this PSM project had been successfully implemented by fulfilling the

requirement as being expend. Beside, the project also achieved the objective in order to

redesign the product and achieved the better design efficiency, handling ratio, and fitting

ratio compared both existing product and redesign. In addition, it was very useful to be

exposed with the use and application of Design for Manufacturing and Assembly

(DFMA) methodology that might very useful to me while facing the real working field in

future undertaking. Lastly, the application of DFMA methodology will be the best

method or approach for nowadays industries to be applied in achieving the bright future.

Figure 6.1: Shows the comparison between existing product and second redesign

Existing

product

120 parts

second

redesign

24 parts

62

6.2 Future works

For this Projek Sarjana Muda, the study was focused more on implantation of DFMA

methodology, and finally came out with a new design of grass cutting machine. Actually,

there are many ways or phases that this project could be done. So, for future works, I

recommended some methods that can be done as follows:

a) Use Morphological Chart method to identify the alternative mechanism

and operation system of the grass cutting machine to be developed.

b) Study the overall costing for design grass cutting machine that had been

developed.

c) Concept Convergence method to analyze and select the best alternatives

based on the quantitative assessment.

d) For student who use DFMA methodology, they sould have collaboration

with industry in order to gain more knowledge, information, and the

technical requirements regarding DFMA implementation.

With all this recommendations, hope that the further study will become more effective

and lead to better result.

63

REFERENCES

Alan F and Jan Chal(1994), Design for Assembly, Principles and Practice. McGraw

HILL BOOK COMPANY, 1994

G. Boothroyd and W. Knight (1993), Manufacturing La Carte: Efficiency:Design for

assembly, IEEE Spectrum., pp. 51-53.

G. Causey (1999), Elements of agility in manufacturing, Ph.D. Dissertation

(Mechanical Engineering), CWRU, January 1999.

Xiaofan Xie (2003) Design for Manufacture and Assembly Dept. of Mechanical

Engineering, University of Utah : PhD thesis.

Vincent Chan and Filippo A. Salustri (2005). Lucas Hull Method [online]. Available :

http://deed.ryerson.ca/~fil/t/dfmlucas.html [October 2007]

D-ESPAT (2007). Apache Reengineering [online] Available:

http://www.despat.com/CS%20-%20Aerospace.html [ December 2007]

TeamSet (2008) TeamSet [online] Available:

http://www.softscout.com/software/Engineering/MechanicalEngineering/TeamSET.ht

ml [January 2008]

David Grieve (2003) Design for Manufacture [online] Avaiable:

http://www.tech.plym.ac.uk/sme/TSOC302/desman1.htm [January 2008]

TeamSet (2008b).Motor Coach Overhead Luggage Rack [online] Avaiable:

http://www.teamset.com/frame2.html [January 2008]

64

Shih-Wen Hsiao (2001) Concurrent design method for developing a new product.

Department of Industrial Design, National Cheng Kung University, Taiwan. PhD

thesis.

Anonymous (1998) TeamSet user guide version 3. CSC Computer Sciences Ltd. (CSC)

Serope Kalpakjian and Schmid, S. R. (2001). Manufacturing Engineering and

Technology. 4th ed. New Jersey: Prentice-Hall.

APPENDIX A

Gant chart PSM 1

Activity W1

W2

W3

W4

W5

W6

W7

W8

W9

W10

W11

W12

W13

W14

Research title confirmation

Understanding research scope and objectives

Finding literatures (books, journals, articles)

that related to research title.

Report writing on Introduction

Report writing on Literature Review

Report writing on Methodology

Checking and editing report

Report submition

Gant chat PSM 2

Activity W1

W2

W3

W4

W5

W6

W7

W8

W9

W10

W11

W12

W13

W14

Analysis data for existing product using

TeamSet

Draw the redesign of existing product using

SolidWork

Analysis data for redesign of existing product

using TeamSet

Best redesign concept

Design for manufacture

Report writing

Checking and editing report

Report submition

APPENDIX B

Design and Development of Grass Cutting machine using DFMA

Methodology

Mohd Ishammudin Bin Mohd Yunus

Faculty of Manufacturing Engineering,

Universiti Teknikal Malaysia Melaka, Hang Tuah Jaya, Melaka

Phone: +6017-6369430, Email: [email protected]

Abstract-This ptoject describes about the

implementation of redesign the grass cutting machine

by using the application of Design for Manufacturing

and Assembly (DFMA) methodology. The scope

based on the existing grass cutting machine and the

appropriate of DFMA methodology. The method used

for gaining the data is from the reassembled the

existing grass cutting machine. From the data

achieved, it can be classified into several categories to

be studied. Data will be analyzed by using Lucas Hull

method to verify the design efficiency, handling ratio

and fitting ratio to achieve. The tools that used is

TeamSET software. The new propose

design and development of grass cutting machine using dfma methodology

Documents