COST REDUCTION STUDY OF AUTOMOTIVE PART USING DFA METHOD:

HEADLAMP

FARHAN BIN AB RAZAK

Thesis submitted in fulfilment of the requirements

for the award of the degree of

Bachelor of Mechanical Engineering with Automotive Engineering

Faculty of Mechanical Engineering

Universiti Malaysia Pahang

DECEMBER 2010

UNIVERSITI MALAYSIA PAHANG

FACULTY OF MECHANICAL ENGINEERING

I certify that the project entitled “Cost Reduction Study of Automotive Part using DFA

Method: Headlamp” is written by Farhan B. Ab Razak. I have examined the final copy

of this project and in our opinion; it is fully adequate in terms of scope and quality for

the award of the degree of Bachelor of Engineering. I herewith recommend that it be

accepted in partial fulfillment of the requirements for the degree of Bachelor of

Mechanical Engineering with Automotive Engineering.

Nur Azhani Binti Abd Razak

Examiner Signature

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SUPERVISOR’S DECLARATION

I hereby declare that I have checked this project and in my opinion, this project is

adequate in terms of scope and quality for the award of the degree of Bachelor of

Mechanical Engineering with Automotive Engineering.

Signature

Name of Supervisor: HADI BIN ABDUL SALAAM

Position: LECTURER OF MECHANICAL ENGINEERING.

Date: 6 DECEMBER 2010

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STUDENT’S DECLARATION

I hereby declare that the work in this project is my own except for quotations and

summaries which have been duly acknowledged. The project has not been accepted for

any degree and is not concurrently submitted for award of other degree.

Signature

Name: FARHAN AB. RAZAK

ID Number: MH07065

Date: 06 DECEMBER 2010

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ACKNOWLEDGEMENT

Assalamualaikum W.B.T. Alhamdulillah, in preparing this thesis, I was in contact with

many people, academicians, and practitioners. They have contributed towards my understanding

and thoughts. In particular, I wish to express my sincere appreciation to my supervisor, Mr. Hadi

Abdul Salaam, for encouragement, guidance, critics and friendship. I am also very thankful to

my previous supervisor, Mr. Mohd Fadzil Faisae Ab Rashid for his guidance, advices and

motivation. Without their continued support and interest, this thesis would not have been the

same as presented here.

I am also indebted to Universiti Malaysia Pahang (UMP) for supplying the product study

and providing the internet facility. My sincere appreciation also extends to all my colleagues and

others who have provided assistance at various occasions. Their views and tips are useful indeed.

Unfortunately, it is not possible to list all of them in this limited space, I am grateful to all my

family members.

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ABSTRACT

The ability to produce new product design with features such as a lower cost,

higher quality than the original product is a key factor in meeting the market demand.

Design for Assembly (DFA) has been widely used in industry and has produced many

successes. Some of the methods known in the DFA industry now are the Boothroyd-

Dewhurst DFA method, Hitachi assemblability analysis method (AEM) and the Lucas

DFA-Hull method. With these well-known methods, many important changes and

developments carried out either manually or through the automatic assembly. The goals

of this project are to analyse existing headlamp using Boothroyd-Dewhurst DFA and

Hitachi Assemblability Evaluation Method (AEM) in terms of assembly time, assembly

cost and assembly efficiency. The headlamp that has been used in this project is a Saga

BLM headlamp. The original headlamp and proposed headlamp design have been

compared between each other’s and the best result is the proposed design which has the

lowest assembly time, lowest assembly cost and highest percentage of design efficiency

that is the third proposed design headlamp for each method.

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ABSTRAK

Keupayaan untuk menghasilkan produk baru yang mempunyai ciri-ciri seperti

mempunyai kos yang rendah, tinggi kualiti daripada produk asal merupakan faktor

utama di dalam memenuhi pasaran. Pemasangan Reka bentuk (DFA) telah banyak

digunakan di dalam industri dan telah menghasilkan pelbagai kejayaan. Antara kaedah-

kaedah DFA yang terkenal di dalam industri sekarang ialah kaedah Boothroyd-

Dewhurst DFA, Kaedah analisis Hitachi assemblability (AEM) dan kaedah DFA Lucas-

Hull. Dengan adanya kaedah-kaedah yang ternama ini, banyak perubahan dan

pembangunan penting dilaksanakan samada pemasangan secara manual ataupun

pemasangan secara automatik. Tujuan dari projek ini adalah untuk menganalisis lampu

depan yang sedia ada dengan menggunakan Boothroyd-Dewhurst DFA dan Hitachi

Assemblability Kaedah Penilaian (AEM) dari segi masa pemasangan, kos pemasangan

dan kecekapan pemasangan. Lampu depan yang digunakan dalam projek ini adalah

lampu depan Saga BLM. Lampu depan yang asal dengan rekaan lampu depan yang

dicadangkan telah dibandingkan antara satu sama lain dan rekaan terbaik ialah rekaan

yang mepunyai masa pemasangan yang paling rendah, kos pemasangan yang paling

rendah dan peratusan tertinggi dari segi kecekapan pemasangan iaitu rekaan lampu

depan yang ketiga bagi setiap kaedah.

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TABLE OF CONTENTS

Page

TITLE PAGE i

SUPERVISOR’S DECLARATION ii

STUDENT’S DECLARATION iii

DEDICATION iv

ACKNOWLEDGEMENT v

ABSTRACT vi

ABSTRAK vii

TABLE OF CONTENTS viii

LIST OF TABLES xi

LIST OF FIGURES xiii

CHAPTER 1 INTRODUCTION

1.1 Introduction 1

1.2 Project Background 1

1.3 Problem Statement 3

1.4 Project Objective 3

1.5 Scope of Study 4

CHAPTER 2 LITERATURE REVIEW

2.1 Introduction 5

2.2 Design for Assembly 5

2.2.1 Comparison of Assembly Method 6

2.2.2 DFA guidelines and Principles 8

2.3 Design for Assembly method 12

2.3.1 Boothroyd-Dewhurst DFA method 13

2.3.2 Hitachi Assemblability Evaluation Method (AEM) 15

2.3.3 Lucas-Hull DFA method 18

2.4 Comparison of DFA methods 20

2.5 Previous Research 21

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2.6 Conclusion 26

CHAPTER 3 METHODOLOGY

3.1 Introduction 27

3.2 Design of project study 27

3.3 Method in separating components of the headlamp 30

3.4 Method in drawing the headlamp 30

3.5 Method of Boothroyd-Dewhurst 30

3.6 Method of Hitachi AEM 32

3.7 Conclusion 33

CHAPTER 4 RESULT AND DISCUSSION

4.1 Introduction 34

4.2 Product Information 34

4.3 Product Design Analysis by using Boothroyd-Dewhurst DFA 36

4.4 Original Design Analysis using Boothroyd-Dewhurst DFA 37

4.5 Original Design Calculations 44

4.6 Improvement of the Original Design using B-D DFA 45

4.7 First proposed headlamp design 45

4.7.1 First proposed headlamp design Analysis 46

4.7.2 First proposed headlamp design Calculations 48

4.8 Second proposed headlamp design 49

4.8.1 Second proposed headlamp design Analysis 50

4.8.2 Second proposed headlamp design Calculations 52

4.9 Third proposed headlamp design 53

4.9.1 Third proposed headlamp design Analysis 53

4.9.2 Third proposed headlamp design Calculations 55

4.10 Original Design Analysis by using Hitachi AEM 56

4.11 Original headlamp Calculation (Hitachi AEM) 60

4.12 Improvement of the original headlamp design by using Hitachi (AEM) 62

4.13 First proposed headlamp design analysis 62

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4.13.1 First proposed headlamp design calculations 66

4.14 Second proposed headlamp design analysis 67

4.14.1 Second proposed headlamp design calculations 70

4.15 Third proposed headlamp design analysis 72

4.15.1 Third proposed headlamp design calculations 75

4.16 Overall Result 76

4.17 Conclusion 77

CHAPTER 5 CONCLUSIONS

5.1 Introduction 78

5.2 Conclusion 78

5.3 Recommendations for Future Works 79

REFERENCES 80

APPENDICES 82

A Gantt Chart for PSM 1 82

B Gantt Chart for PSM 2 83

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LIST OF TABLES

Table No. Title Page

2.1 DFA methods comparison 21

2.2 Summary of previous research 24

3.1 DFA worksheet 31

3.2 Worksheet of Hitachi AEM 32

4.1 Information of the Headlamp Components 37

4.2 Boothroyd-Dewhurst DFA worksheet for original Saga BLM headlamp

design 42

4.3 Boothroyd-dewhurst DFA worksheet for first proposed Saga BLM

headlamp design 46

4.4 Boothroyd-Dewhurst DFA worksheet for second proposed Saga BLM

headlamp design 50

4.5 Boothroyd-Dewhurst DFA worksheet for third proposed Saga BLM

headlamp design 53

4.6(a) Hitachi AEM worksheet for sub-assembly parts of original Saga BLM

headlamp design 57

4.6(b) Hitachi AEM for main parts of original Saga BLM headlamp design 58

4.7(a) Hitachi AEM worksheet for sub-assembly parts of first proposed Saga

BLM headlamp design 62

4.7(b) Hitachi AEM worksheet for main parts of first proposed Saga BLM

headlamp design 63

4.8(a) Hitachi AEM worksheet for sub-assembly parts of second proposed Saga

BLM headlamp design 67

4.8(b) Hitachi AEM worksheet for main parts of second proposed Saga BLM

headlamp design 68

4.9(a) Hitachi AEM worksheet for sub-assembly parts of third proposed Saga

BLM headlamp design 71

4.9(b) Hitachi AEM worksheet for main parts of the third proposed Saga BLM

headlamp design 72

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4.10(a) Total result of all headlamp design using B-D DFA 75

4.10(b) Total result of all headlamp design using Hitachi AEM 75

xiii

LIST OF FIGURES

Figure No. Title Page

2.1 Relative costs of different assembly methods by type and production

Volume 7

2.2 Production ranges for each type of assembly method 7

2.3 Design to avoid an adjustment during insertion 9

2.4 Standardize parts 9

2.5 Features affecting part handling 10

2.6 Design to aid insertion 10

2.7 Results of DFA analysis 11

2.8 Features of Hitachi Assemblability Evaluation Method (AEM) 15

2.9 Example of the AEM Symbols and Penalty Scores 16

2.10 Flowchart of Hitachi Assembly Evaluation Method 17

3.1 Project flowchart 29

4.1 Picture of Proton Saga BLM 35

4.2 Bolt with the signal housing 44

4.3 Snap fit 45

4.4 2 Bolts, 1 Supporter and Bracket 48

4.5 Supporter combined with the Bracket 48

4.6 Example of the AEM symbols and the penalty score 55

4.7 Product tree diagram for Saga BLM headlamp 56

4.8(a) Bolt with the Signal Housing 61

4.8(b) Snap fit 61

4.9(a) Signal bulb and lower bulb in original assembly direction 66

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4.9(b) Signal bulb and lower bulb in proposed design assembly direction 66

CHAPTER 1

INTRODUCTION

1.1 INTRODUCTION

This chapter discussed about Design for Assembly (DFA) method, project

background, problem statement, research objectives, and the scope of study. These

information are important to give a starting point for the progress in this project. This

project is focused on studying about assembly cost reduction of car headlamp using

Boothroyd-Dewhurst DFA and Hitachi Assemblability Evaluation Method (AEM)

approaches.

1.2 PROJECT BACKGROUND

Traditionally, product development was essentially done in several stages. The

designer would design the product, and sometimes would construct working prototypes.

Once the prototype was tested and approved, the manufacturing team would then

construct manufacturing plans for the product, including the tooling etc. Often, different

materials like different thickness or type of sheet metal, and different components like

different sized screws would be substituted by the manufacturing team. Their goal was

to achieve the same functionality, but make mass production more efficient. However,

the majority of the design remained unchanged, since the manufacturing engineers

could never be sure whether a change would affect some functional requirement. There

are two things changed in the 1970’s, firstly, many new types of plastics were

developed, and injection moulding technology became widely available, resulting in the

possibility of low cost plastic components. An advantage of these new plastic materials

was that they provided different material behavior. Thus, parts that had to be made from

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metal and screwed together could just be made out of plastic and snap fitted. This

reduced assembly time, assembly components, and production costs.

Secondly, several companies were trying to bring their products to the market

faster. One problem with the earlier method of doing things was that each time there

was a design change made by the manufacturing engineer, product development was

held up, waiting for the Engineering Change Notice (ECN) to be approved by the

designer. Often, this process introduced delays because the design engineer would be

busy with other tasks, or unavailable. To avoid this, the concept of Concurrent

Engineering (CE) became popular. The idea here was that a combined team of

engineers and management would be assigned to each new product. This team may

consist of mechanical designers, electrical engineers, software engineers, production

engineers, marketing and sales, and management. Thus, as the design was being

generated by the designers, the production people would give feedback about feasibility

to manufacture, more economical alternatives etc. At the same time, sales people would

negotiate of product outlook and features, and so on. The biggest advantage of CE was

that the product was designed in a way that manufacturing cost and time would be low

during production.

At this time, working with many different companies, Boothroyd’s team

analysed existing designs of hundreds of products, and suggested design improvements

based on manufacturing and assembly ease. Using the experience of these projects, they

then developed a very large set of guidelines on how to estimate whether a design was

designed well from a manufacturing point of view and potential methods to improve the

designs.

Generally, there are three DFA methods used to reduce the cost of the product.

The main methods are Boothroyd-Dewhurst DFA method, Lucas-Hull DFA method and

Hitachi Assemblabitily Evaluation Method (AEM). This project is about applying

Boothroyd-Dewhurst DFA and Hitachi Assemblability Evaluation Method (AEM) to

make a new proposed design of headlamp which is better in the aspect of assembly cost,

assembly time and assembly efficiency than the original one. This case study focused

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on redesigning the car headlamp and the aim of analysis is to reduce the assembly cost

for the headlamp.

1.3 PROBLEM STATEMENT

Headlamp normally consists of many components and parts from the bulb to the

reflector of the lamp. In automotives industry, the components of the lamp are

assembled and combined together to produce the headlamp. During this process, there

are some parts of headlamp that are difficult to be assembled which means it takes more

time to be assembled and as a result, the cost also increased.

In order to solve this problem, the project is done. The project also aims to

minimize the difficulties encountered during assembly of the components of the

headlamp. By using two methods of DFA which are Boothroyd-Dewhurst DFA and

Hitachi Assemblability Evaluation Method (AEM), the existing design of headlamp was

improved according to DFA guidelines and with the improvements that have been made

in proposed design, the comparison between existing and proposed headlamp design in

term of cost assembly, assembly time and assembly efficiency must be made in order to

know whether the improvements are quite good or not.

1.4 PROJECT OBJECTIVES

The objectives are stated stated as below:

1. To analyse existing headlamp in term of assembly cost, assembly time and

assembly efficiency by using Boothroyd-Dewhurst DFA and Hitachi (AEM)

methods.

2. To come out with suggestions to reduce assembly cost for the headlamp.

3. To determine the assembly cost before and after improvement.

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1.5 SCOPE OF STUDY

The scopes of this project are follows:

1. The CAD design of the original and the proposed design of the headlamp are

done using Solidworks 2009 software.

2. Analysis of the original design and the proposed design of the headlamp are

performed by using Boothroyd-Dewhurst DFA and Hitachi Assemblability

Evaluation Method (AEM) methods.

3. Limited to headlamp for Saga BLM only and the proposed design is for

suggestion purpose to manufacturer.

CHAPTER 2

LITERATURE REVIEW

2.1 INTRODUCTION

This chapter discussed about the DFA and its guidelines. Besides that, the

literature review gives a brief explanation about the functions and the principles of the

DFA which is subcomponent of the DFMA itself. Some of the information in this

chapter can give extra information which can be useful while doing this project.

2.2 DESIGN FOR ASSEMBLY (DFA)

Assembly is a major part in product manufacturing process and the function is to

joint all the components and turn it as a complete product (Boothroyd et al., 2002).

Design for Assembly is an approach to reduce cost of the product and time to assemble

the product by simplifying the process and product. The DFA method should be

considered at all stages of the design process especially in the early stages (Boothroyd

et al., 1994). Using DFA tool, the product assembly could be analyse in effective way.

The aim of Design for Assembly (DFA) is to simplify the product so that the

cost of assembly is reduced. However, consequences of applying DFA usually include

improved quality and reliability, and a reduction in production equipment and part

inventory. These secondary benefits often outweigh the cost reductions in assembly.

DFA recognises the need to analyse both the part design and the whole product

for any assembly problems early in the design process. We may define DFA as process

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for improving product design for easy and low-cost assembly, focusing on functionality

and on assemblability concurrently.

The practice of DFA as a distinct feature of designing is a relatively recent

development, but many companies have been essentially doing DFA for a long time.

For example, General Electric published an internal manufacturing product ability

handbook in the 1960's as a set of guidelines and manufacturing data for designers to

follow. These guidelines embedded many of the principles of DFA without ever

actually calling it that or distinguishing it from the rest of the product development

process.

It was not until the 1970's that papers and books on the topic began to appear.

Most important among these were the publications of G. Boothroyd that promoted the

use of DFA in industry.

2.2.1 Comparison of Assembly Method

There are three method of assembly such as manual assembly, automatic

assembly and robotic assembly (Boothroyd et al., 2002). What considerations affect the

choice of methods? For manual assembly, the cost is fixed per unit regardless of the

production volume. Fixed automatic assembly such as injection molded part, the more

units produced, the closer it will get to just the cost of the materials (spreading fixed

tooling costs and capital). Robotic or flexible assembly allows capital costs to spread

across multiple uses, making cost per unit non-linear at lower volumes.

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Figure 2.1: Relative costs of different assembly methods by type and production

volume.

Source: Mital et al. (2007)

Graphically, the cost of different assembly methods can be displayed as in

Figure 1. The non-linear cost for robotic assembly reflects the non-linear costs of robots

even small ones cost a lot.

Figure 2.2: Production ranges for each type of assembly method

Source: Mital et al. (2007)

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The appropriate ranges for each type of assembly method are shown

approximately in Figure 2. Assembly methods should be chosen to prevent bottlenecks

in the process, as well as lower costs.

2.2.2 DFA Guidelines and Principles

DFA applies to all the assembly operations, such as parts feeding, separating,

orienting, handling, and insertion for automatic or manual assembly (Ghosh and

Gagnon, 1989). Many factors can affect the reliability of the assembly operation.

Several guidelines have been determined which can improve the reliability and the ease

of the assembly. The DFA guidelines can be summarized as below (Otto and Wood,

2001).

1. Assemble only in open space, not in confined or restricted space. Never bury

important components.

2. Minimise part count by incorporating multiple functions into single parts.

3. Modularise multiple parts into single subassemblies. (see Figure 2.3 )

4. Make parts to identify how to orient them for insertion.

5. Standardise to reduce part variety (see Figure 2.4 )

6. Maximise part symmetry (see Figure 2.5 (a) )

7. Design in geometric or weight polar properties if nonsymmetric.

8. Eliminate tangly parts. (see Figure 2.5 (d) )

9. Color code parts that are different but shaped similarly.

10. Prevent nesting of parts.

11. Provide orienting features on nonsymmetries.

12. Design the mating features for easy insertion. (see Figure 2.6 )

13. Provide alignment features.

14. Insert new parts into assembly from above.

15. Insert from the same direction or very few. Never require the assembly to be

turned over.

16. Eliminate fasteners.

17. Place fasteners away from obstructions.

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18. Deep channels should be sufficiently wide to provide access to fastening tools.

No channel is best.

19. Providing flats for uniform fastening and fastening ease.

20. Proper spacing ensures allowance for a fastening tool.

Figure 2.3: Design to avoid an adjustment during insertion

Source: Boothroyd et al. (2002)

Figure 2.4: Standardize parts.

Source: Boothroyd et al. (2002)

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Figure 2.5: Features affecting part handling

Source: Boothroyd et al. (2002)

Figure 2.6: Design to aid insertion

Source: Boothroyd et al. (2002)