UNIVERSITI PUTRA MALAYSIA

FABRICATION OF COOLING JIG USING ELECTRO

DISCHARGE MACHINING (EDM)

AZMAN BIN SENIN

FK 2002 68

FABRICATION OF COOLING JIG USING ELECTRO DISCHARGE MACHINING (EDM)

By

AZMAN BIN SENIN

Thesis Submitted to the School of Graduate Studies, Universiti Putra Malaysia, in Fulfilment of Requirement for the Degree of Master of Science

August 2002

Abstract of thesis presented to the Senate of Universiti Putra Malaysia in fulfilment of the requirements for the degree of Master of Science

FABRICATION OF COOLING JIG USING ELECTRO DISCHARGE MACHINING (EDM)

By

AZMANSENIN

August 2002

Chairman: Napsiah Ismail, Ph.D.

Faculty: Engineering

For a high quantity production system such as PROTON, maintenance of equipments

and related facilities at the production line is one of the critical factors to ensure the

success of Just In Time system (JIT) and Synchronised System. A higher breakdown

of equipments will affect the delivery to next processes and uncertain level of quality.

This project focused on body assembly process where this process is the second

process in Proton cars manufacturing process. It features a mix of a variety type of

welding assembly jig, welding equipments, material handling equipments and robots.

A demand arises when the spare part of existing welding assembly jig - Cooling Jig is

not available and extensive maintenance is required in maintaining the Cooling Jig.

This project focus on re-modelled and fabrication of Cooling Jig. The fabrication

process needs information on surface data instead of detail drawing. But, the

111

information such as surface data is not available in Jig Making & Maintenance (JMM)

section. The surface data is obtained thorough digitising process with coordinate

measuring machine and produced the Cloud point data in a neutral data format (ASCII

format). Then, Catia software was used to convert the file into DXF format. The

Cooling Jig's surface was obtained first before NC data conversion can be generated.

The fabrication of Cooling Jig is using EDM wire cut. Prior to machining, the Design

of Experiment (DOE) was used as a method to obtain the optimum machining time and

wire breakage without carrying numerous numbers of experiments at EDM Wire Cut

machine - R290P, Agie Charmilles.

As a result, the In-House fabrication process reduced almost 60 % fabrication cost if

outsourced and successfully forged a reverse engineering flows for JMM section.

IV

Abstrak tesis yang dikemukan kepada Senat Universiti Putra Malaysia sebagai memenuhi keperluan ijazah Master Sains

PROSES FABRIKASI BAGI COOLING JIG MENGGUNAKAN ELECTRO DISCHARGE MACHINING(EDM)

Oleh

AZMAN SENIN

Ogos 2002

Pengerusi: Napsiah Ismail, Ph.D.

Fakulti: Kejuruteraan

Untuk sistem pengeluaran yang berkapasiti tinggi seperti PROTON, penyelenggaraan

untuk peralatan-peralatan dan lain-lain kemudahan yang berkaitan merupakan salah

satu faktor yang menentukan kejayaan sistem "Just In Time" dan system

"Synchronised".

Projek ini memfokus kepada proses Pemasangan Badan dimana proses ini adalah

proses kedua dalam pembuatan kereta PROTON. Ia terdiri daripada pelbagai jenis "

Welding Assembly Jig", peralatan kimpalan, peralatan "Material Handling" dan

robot. Keperluan timbul apabila tiada alat-alat ganti bagi "Cooling Jig" dan ianya

juga memerlukan penyelenggaraan yang intensif.

Proses fabrikasi memerlukan maklumat bagi permukaan bersentuh diantara "Cooling

Jig" dan panel "Body-In-White". Namun maklumat yang diperlukan adalah tiada di

Seksyen "Jig Maintenance & Making". Data permukaan diperolehi melalui proses

v

"digitising" dengan "Coordinate Measuring Machine" dan menghasilkan data "Cloud

Point" dalam format data neutral (format ASCII). Seterusnya, CATIA digunakan untuk

menukarkan fail tersebut kepada fail dalam format DXF. Permukaan "Cooling Jig"

dibentuk terlebih dahulu sebelum ditukarkan kepada data NC. "Design of Experiment"

telah digunakan sebagai salah satu kaedah mendapatkan masa pemotongan yang

minimum dan juga "Wire Breakage" tanpa perIu menjalankan banyak ekperimen di

mesin "EDM Wire Cut" - R290P,Agie Charmilles.

Dalam bentuk kewangan, penjimatan hampir 60% telah dicapai sekiranya proses

fabrikasi dijalankan diluar atau dibeli.Seterusnya, proses fabrikasi "Cooling Jig telah

membentuk "System Operation Procedure"(S.O.P) untuk proses "Reverse Engineering"

di Jig Making & Maintenance (JMM).

Vl

ACKNOWLEDGEMENTS

In preparing this thesis, I have a great many people to thank. First, the

Supervisory committee because of their support, guidance and understanding.

I also wish to acknowledge the multitude of assistance that has been provided

by PROTON's staff especially from Engineering Design Section (R&D

Division), Prototype Section (R&D Division) and Die Jig Making and

Maintenance (Manufacturing Division).Heartfelt thanks are due to my family,

especially my wife (Nazlina Mohd Nawi) and my daughter (Nur Aqilah) for

their loving support. Thanks again and may AILAH bless all of you.

Vll

I certify that an Examination Committee met on 28th August 2002 to conduct the final examination of Azman Bin Senin on his Master of Science thesis entitled

"Fabrication of Cooling Jig Using Electro Discharge Machining (EDM)" in

accordance with Universiti Pertanian Malaysia (Higher Degree) Act 1980 and U niversiti Pertanian Malaysia (Higher Degree) Regulations 1981. The Committee recommends that the candidate be awarded the relevant degree. Members of the Examination Committee are as follows:

Md. Yusof Ismail, Ph.D. Faculty of Engineering, Universiti Putra Malaysia. (Chairman)

Napsiah Ismail, Ph.D. F acuity of Engineering, Universiti Putra Malaysia. (Member)

Shamsuddin Sulaiman, Ph.D. Associate Professor, Faculty of Engineering, Universiti Putra Malaysia. (Member)

Wong Soon Van, Ph.D. Faculty of Engineering, Universiti Putra Malaysia. (Member)

AINI IDERIS, Ph.D. ProfessorlDean School of Graduate Studies, Universiti Putra Malaysia.

Date: 2 5 OCT 2002

viii

This thesis was submitted to the Senate of Universiti Putra Malaysia and has been accepted as fulfilment of the requirements for the degree of Master of Science. The members of the Supervisory Committee are as follows:

Napsiah Ismail, Ph.D. Faculty of Engineering, Universiti Putra Malaysia. (Chairman)

Shams uddin Sulaiman, Ph.D. Associate Professor, Faculty of Engineering, Universiti Putra Malaysia. (Member)

Wong Soon Van, Ph.D. Faculty of Engineering, Universiti Putra Malaysia. (Member)

lX

AINI IDERIS, Ph.D, Professor I Dean, School of Graduate Studies, Universiti Putra Malaysia

Date:

DECLARATION

I hereby declare that the thesis is based on my original work except for quotations and citations which have been duly acknowledged. I also declare that it has not been previously or concurrently submitted for any other degree at UPM or other institutions.

Date: :JS· /6. 02.

x

TABLE OF CONTENTS

Page

DEDICATION . . . ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... 11

ABSTRACT . . . ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... 111

ABSTRAK . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . v

ACKNOWLEDGEMENTS . .. ... ... ... ... ... ... ... ... ... ... ... ... ... ... Vll

APPROVAL SHEETS . . . ... ... ... ... ... ... ... ... ... ... ... ... ... ... V111

DECLARATION . . . . . . '" ... ... ... ... ... ... ... ... ... ... ... ... IX

LIST OF TABLES . , . ... ... ... ... ... ... ... . . . ... ... ... ... ... ... X111

LIST OF FIGURES . . . ... ... ... ... ... ... ... ... ... ... ... ... ... ... XIV

LIST OF ABBREVIATIONS ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... xv

CHAPTER

1. INTRODUCTION ' " ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... .. 1 1.1 Project Background ... ... ... ... ... ... ... ... ... ... ... ... . .. ... ... .. 1 1.2 Problem Definition . . . . . . . . . . . . . . . . . . . . . . .. ..... . .. . .. . . , . ... . . . .. 4 1.3 Objective . . . ... .. . ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... .. 9 1.4 Organisation of Thesis . . . . .. ... ... . . . . .. ... ... ... ... ... ... .. 10

2. LITERATURE REVIEW ...... ... ... ...... ............ ...... ... ... ..... 11 2.1 Background . . . .. . . .. ... . .. ... ... ... ... ... . .. . .. ... ... ... ... ... ... .. 11 2.2 Electrical Discharge Machine . , . ... ... ... ... .. , ... ... ..... 12 2.3 Machining Parameter ... ... ... ... ... ... ... ... ... ... ... ... .. 16 2.4 Coordinate Measuring Machine . . . ... ... ... ... ... ... ... ... .. 20 2.5 Data Exchange Standard . . . ... ... ... ... ... ... ... ... ... ... ..... 24 2.6 Geometric Modelling Scheme . . . ... ... ... ... ... ... ... ..... 29 2.7 Reverse Engineering . . . ... ... ... ... ... ... ... ... ... ... ..... 36 2.8 Jig and Fixture . . . ... ... ... ... ... ... ... ... ... ... ..... 41 2.9 Process Selection for Fabrication Work of Cooling Jig 44

3. METHODOLGY ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... .... 46 3.1 Introduction ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ..... 46 3.2 Coordinate Measurement... . . . ... ... ... ... ... ... ... ... ... ... ... ... ..... 48 3.3 Geometry Conversion . . . ... ... ... ... ... ... ... ... ... ... ..... 49 3.4 Geometry Editing ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... .. 49 3.5 NC Generation ... ... ... ... ... ... ... ... ... ... ... ... ... ... ..... 50 3.6 Wire Cutting Process . .. ... ... ... ... ... ... ... ... ... ... ..... 50 3.7 Inspection . . . ... ... ... ... ... ... ... ... ... ... ... ... ... ... .. 51 3.8 Pre Wire Cut Process .. . ... ... ... ... ... ... ... ... ... ... ... ... ... ..... 52

Xl

4.

5.

RESULTS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

4.1 Introduction ... .... " . .. . . . ... . . . . . . ... .... " . . . ... . . . .. . 4.2 Coordinate Measurement ......... ' " . . . . . . . . . ' " . . . . . . . . . ' "

4.3 Geometry Conversion ... ... ' " . . . . . . . . . .. . . . . . .. . .. ' " . . . . . . . , . . . .

4.4 Geometry Editing ... ... ' " . ... .. . .. . ........ ...... . . . . ..... ' "

4.5 Pre Wire Cut Process ...... ' " . . . . . . . . . .. . . . . .. . . , . . . . . . . . . . . . . . . .

4.6 Wire Cutting Process ... ... ... ... ..... , ' " .. . . .. ... ... . . . . . . . . . .. .

4.7 Machining Parameter ......... ... ...... ............... ... ...... ' "

4.8 Experiment Set Up ...... ' " . . . . . . . . . . .. . . . ... .... . . . .. . . . . . . ' "

4.9 Experiment Results ..... , .. . . . . . .. . . . .. . . .. ... ... . . . . . . ... .. . .. .

4.10 Experiment Vs Actual Results ...... ... ............ ..... .

4.11 Inspection ... ... ... ...... ............ ... ... ... ... ..... .

4.12 Summary ... ...... ... ............... ... .............. .

CONCLUSION ... ...... ... ... ...... ... ... ........ ......... ......... .

5.1 Conclusion ... .................. ... ......... ... ........ .

5.2 Recommendations for Future Study .......................... .

REFERENCES

APPENDICES A B C D E F

The Picture of Old and Newly Cooling Jig ........ , . . . . . . . . . .

Cost Analysis ...... ... ... ... ... ...... ............................. . The Picture of TP2 at CMM machine and EDM Wire-Cut .. .

Cloud Points for Cooling Jig ...... ...... ...... ... ... ... ... ..... .

Geometry Conversion ...... ... ' " ... ... ... ' " . .. ... .. , ' "

NC Data for Cooling Jig ... ... ... ... ... .................... .

BIODATA OF THE AUTHOR

xii

53 53 53 54 54 55 59 60 61 64 66 66 67

73 73 74

76

80 81 82 83 102 103

109

LIST OF TABLES

Table page

2.1 Values ofEL and PA 17

2.2 Classification of Jigs 43

4.1 Specification of Brass Wire 6 1

4.2 Characteristics of Brass Wire 61

4.3 Settings of Machining Parameters 62

4.4 Property of Brass 63

4.5 Experiment Result 64

4.6 Comparison Between Experiment and Actual result 66

xiii

LIST OF FIGURES

Figure Page

1.1 Application of Cooling Jig where it is clamped to Body-In-White panel 5

1.2 Cooling Jig structure 6

1.3 Details drawing of cooling jig 7

2.1 Types of CMM construction 21

2.2 Neutral Data format for Data Exchange 24

2.3 Ambiguity in wire frame model 30

2.4 Faceted representation of a cylinder 35

2.5 CSG model of a simple block 36

2.6 Classification of data acquisition methods 38

3.1 Flowchart of fabrication process of Cooling Jig 47

4.1 Workpiece Diagram for Process Planning 56

4.2 Machining Process Planning, pg 1 Of 2 57

4.3 Machining Process Planning, pg 2 Of 2 58

4.4 Reverse Engineering Technique for JMM 69

4.5 Coordinate Measurement for Reverse Engineering Technique 70

4.6 Setting Process for Coordinate Measurement 71

4.7 Surface Model of Cooling Jig 72

4.8 Work Part after Machining Process 72

XlV

ASCII

CNC

DOE

DXF

EDM

IGES

JMM

MCU

NC

STEP

LIST OF ABBREVIATIONS

American Standard Code for Information Interchange

Computer Numerical Control

Design of Experiment

Data Exchange Format

Electrical Discharge Machine

Initial Graphics Exchange Specification

Jig Making and Maintenance

Machine Control Unit

Numerical Control

Standard for the Exchange of Product Model Data

xv

CHAPTER 1

INTRODUCTION

1.1 Project Background

The classification of production activities are justified according to the

quantity of product produce whereas the classification falls into 3 categories,

namely Mass production, Batch production and Job shop production

(Groover,2001 ).

In mass production classification, it has specialised in manufacture of

identical products. Mass production is characterised by a very high production

rates, specialised equipment and tooling that are completely dedicated to the

manufacture of a particular products. The investment in specialised tooling and

equipments are proportionally high. The skill of workers are low where it was

transferred from worker to the specialised tooling.

The batch production classification involves the manufacture of mediwn­

sized lots of the same parts or products. The lots may be produced only once or

produce at regular interval. The manufacturing equipment used is general-purpose

but designed for higher production rate. It also involves specialised tooling to

achieve high production rate. The plant is capable of high production rate that

exceed the demand rate. Therefore, the plant produces to build up an inventory of

the part. Then it changes to other orders and parts. When the stocks of the

1

previous parts become depleted, production is repeated to build up the inventory

agam.

Production system in PROTON can be stipulated into 4 processes;

Stamping, Body Assembly, Painting and Trim & Final. Stamping meets the

criteria of Batch production and it was the first process in the manufacturing of a

car. While the Body Assembly, painting and Trim & Final can be categorised into

mass production, where they are a continuous processes until a car is ready to

deliver. Below outline will give a general background of the 4 processes that

involved in the manufacturing of PROTON cars.

a) Stamping

Stamping consists of semi-automated equipment that have been

synchronised to supply the line with parts on an almost just-in-time (JIT) basis.

This affords the line to carry minimal buffer stock, thus saving space and

inventory costs. With the eventual adoption of the just-in-time . method of

production, PROTON has incorporated a subsidiary company, PMM (PROTON

Mitsubishi Metal) that handles and delivers blank parts to stamping. Stamping is

the first process in car manufacturing work. The Stamping line consists of semi­

automated equipment that have been synchronised to supply parts to the body

assembly line on an almost just-in-time basis (PROTON Bhd, 1998).

2

b) Body Assembly

This process features a mix of manual and fully-automated activities

incorporating the use of robot welders. This section of the pr�uction line has

been equipped with an auxiliary line that manufactures components as and when

they are required for a sub-assembly that is being built-up. Body Assembly is the

second process; where cars parts are assembled into a complete unit of 'body-in­

white'. The line mixes manual and fully-automated activities using robot welders

as well as an auxiliary line that manufactures (PROTON Bhd, 1998).

c) Painting

In this process, a sophisticated painting system (the Micro-Micro Bell

Electrostatic Auto Spray System) is used to affect a consistent layer of paint on a

car's body, resulting in a near-mirror finish. The system also allows the use of

materials to be precisely controlled, and incorporates a self-cleaning feature which

ensures that the spraying equipment is always clean and in excellent condition.

This new system as opposed to the previous one which was manually operated,

has triggered savings on the consumption of paints and maintenance costs. More

importantly, it has improved the quality of paintwoIk on PROTON cars

(PROTON Bhd, 1998).

3

d) Trim & Final

Here, in the final process, the interior components of the car are installed

and the finishing touches are added. Each PROTON car is put through an

extensive battery of static and dynamic tests to verify its safety, roadworthiness,

drivability, emissions level, and other characteristics. Each car is driven through a

shower test to ensure that it is water-tight by exposing the car to three metric tons

of falling water per minute for a period of five minutes. A car that graduates from

the Trim and Final Assembly process receives the eventual seal of approval and

its owner can be rest assured that the car has met PROTON's exacting standards

for quality and performance.

Trim And Final is the last process in the car manufacturing activity, where

trimmings, chassis and engine are installed to the painted car, and final testings,

including leakage inspection using shower tester are done to 'completely built-up

unit' (CBU) cars (PROTON Bhd, 1998).

1.2 Problem Definition

The assembly process - Body Assembly in car manufacturing system uses

a various types of equipment such as Welding gun, Assembly jigs, Hemming dies,

shuttle transfer, trolley and etc. In Jig Making & Maintenance (JMM), major

responsibility is to maintain and manufacture assembly jig for welding process.

The function of the assembly jig is to hold stamped part or semi-assembled parts

4

at a specified arrangement before welding process is carried out and meets assembly

accuracy in mass quantity. There is various types of assembly jig in assembly

process. However, this project will focus on one type of assembly jig - Cooling Jig.

To understand in deep, the application of Cooling jig is illustrated in Figure 1.1.

Figure I.I: Application of Cooling Jig where it is clamped to

Body-In-White panel.

5

The curvature portion is the contacted surface between Cooling Jig and Body­

In-White panel where this portion or profile should match with Body-In-White panel.

The picture of the structure of cooling jig is shown in Figure 1.2 while Figure 1.3

shows the detail drawing of cooling jig.

,

Figure 1.2: Cooling Jig structure

6

Since the cooling jig was used intensively at production line, a few

portions of cooling jig need major repairs and rectifications. One of the major

problem is the flow of chilling water is not smooth enough where there is leaking

at joining portion. The chilled water drops through the leaks and create a pool of

water on the parts. After 6 hours, the parts that pool the water turn rusty. The

repair process takes 2 days to complete from dismantling and re-install the cooling

jig at production line. And at the same time, the production line has to stop in

order to facilitate the repair process of cooling jig. Therefore, the production will

loss about 1200 units of car if the production stop for 2 days. This figure is so big

and another alternative is fabricating a new sets of cooling jig where the cost is

only RM 1832.00 if produced at Jig Making & Maintenance (JMM).

Since PROTON has a few advantages to fabricate the cooling jig due the

availability of related equipment such as Coordinate Measuring Machine (CMM),

3D Magic Software, CATIA software, POWERSHAPE software and EDM wire

cut machine. The study showed that the in-house fabrication process reduced 60%

of fabrication process if the cooling jig was purchased from vendor as illustrated

in Appendix B.

8

For example, the EDM wire cut machine is used to cut the

curvature portion inside cooling jig. The process leaves no burrs on the edges. It is

also produce a good surface finish with a single cut where it is between 20

microns to 30 microns. With the flexibility of wire movements, the machine is

also capable to cut the taper portion or conic section up to 300 in angle at 40 mm

thickness (Charmilles Technologies(Nc Manual), 1999).

1.3 Objective

The objectives of this project are:

1. To develop a new System Operation procedure (S.O.P)

for Coordinate Measuring Work, Data conversion process

And Machining work to produce Cooling Jig.

11. To generate a surface data for curvature surface of

Cooling Jig.

111. To establish flowchart for the related machining process

For fabrication process for Cooling Jig.

9

1.4 Organisation of Thesis

There are five chapters in the thesis. The first chapter is an

introduction to manufacturing process of PROTON cars. Definition of

problems and objectives of this project are described. in this chapter.

Chapter two outlined the basic and advancement in Machine Tool

technology that enable the fabrication process of complex parts. Chapter

two also outlined a brief description on neutral data fonnat and file

exchange in CAD/CAM environment. A brief explanation on Design of

Experiment was also given. In chapter three, each process in fabrication

process of Cooling Jig was explained briefly. All the processes were

summarised and simplified in flow chart manner. Chapter four outlined the

experiments where the assumptions, experiment set up and experiment

results were described and shown. The last chapter - chapter five has the

conclusions and observations on each process in fabrication process of

Cooling Jig.

10