EFFECT OF EDM DIE-SINKING PARAMETERS ON THE

MATERIAL CHARACTERISTICS OF ALUMINIUM

ALLOY LM6 USING COOPER TUNGSTEN

NOR HALIDA ILYANI BINTI KAMARUDIN

B050910307

UNIVERSITI TEKNIKAL MALAYSIA MELAKA

2013

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UNIVERSITI TEKNIKAL MALAYSIA MELAKA

EFFECT OF EDM DIE-SINKING PARAMETERS ON THE

MATERIAL CHARACTERISTICS OF ALUMINIUM ALLOY LM6

USING COOPER TUNGSTEN

This report submitted in accordance with requirement of the Universiti Teknikal

Malaysia Melaka (UTeM) for the Bachelor Degree of Manufacturing Engineering

(Manufacturing Process) (Hons.)

by

NOR HALIDA ILYANI BINTI KAMARUDIN

B 050910307

860605115258

FACULTY OF MANUFACTURING ENGINEERING

2013

UNIVERSITI TEKNIKAL MALAYSIA MELAKA

BORANG PENGESAHAN STATUS LAPORAN PROJEK SARJANA MUDA

TAJUK: Effect of EDM Die-Sinking Parameters on the Material Characteristics of Aluminium Alloy LM6 Using Cooper Tungsten

SESI PENGAJIAN: 2012/13 Saya NOR HALIDA ILYANI BINTI KAMARUDIN

mengakumembenarkanLaporan PSM inidisimpan di Perpustakaan Universiti Teknikal Malaysia Melaka (UTeM) dengansyarat-syaratkegunaansepertiberikut:

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untuk tujuan pengajian sahaja dengan izin penulis. 3. Perpustakaan dibenarkan membuat salinan laporan PSM ini sebagai bahan

pertukaran antara institusi pengajian tinggi.

4. **Silatandakan ( )

SULIT

TERHAD

TIDAK TERHAD

(Mengandungimaklumat yang berdarjahkeselamatanataukepentingan Malaysiasebagaimana yang termaktubdalamAKTA RAHSIA RASMI 1972) (Mengandungimaklumat TERHAD yang telahditentukanolehorganisasi/badan di

manapenyelidikandijalankan)

AlamatTetap:

Lot 4708 Taman Bistari,

Depan SMK Pelagat, 22000 Jerteh,

Terengganu

Tarikh: ________________________

Disahkanoleh:

Cop Rasmi:

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** Jika Laporan PSM ini SULIT atau TERHAD, sila lampirkan surat daripada pihak berkuasa/organisasi berkenaan dengan menyatakan sekali sebab dan tempoh laporan PSM ini perlu dikelaskan sebagai SULIT atau TERHAD.

DECLARATION

I hereby, declared this report entitled “Effect Of EDM Die-Sinking Parameters On

The Material Characteristics of Aluminium Alloy Lm6 Using Cooper Tungsten

” is the results of my own research except as cited in references.

Signature : ………………………………………….

Author’s Name : Nor Halida Ilyani Binti Kamarudin

Date : …………………………………………

APPROVAL

This report is submitted to the Faculty of Manufacturing Engineering of UTeM

as a partial fulfillment of the requirements for the degree of Bachelor of

Manufacturing Engineering (Manufacturing Process) (Hons.). The member of

the supervisory is as follow:

………………………………

i

ABSTRAK

Electric discharge machine (EDM) adalah proses untuk memotong logam keras dan

membentuk secara mendalam dengan cara hakisan arka dalam semua jenis bahan

konduktif. Ia adalah salah satu daripada proses pemesinan bukan tradisional yang

melibatkan pelepasan percikan fana melalui bendalir disebabkan oleh perbezaan

potensi antara elektrod dan bahan kerja. EDM banyak digunakan di mana bentuk

yang kompleks rumit perlu dimesin dalam bahan-bahan yang sangat keras seperti

keluli alat keras. Projek ini mengkaji ciri-ciri EDM hasil dari electrode wear rate

(EWR), material removal rate (MRR), surface roughness (Ra), dan pemerhatian

kawah pada permukaan bahan kerja. Eksperimen telah dilakukan menggunakan

mesin EDM SODICK AQ35L. Design of experiment(DOE) dengan menggunakan

taguchi method telah digunakan untuk mereka bentuk jadual eksperimen ujian, dan

menganalisis faktor penting yang mempengaruhi ciri-ciri pemesinan untuk proses

EDM. Sebanyak sembilan ujikaji telah dijalankan dengan setiap satu diulang

sebanyak tiga kali. Keputusan yang diperolehi daripada kajian ini menunjukkan

bahawa current, pulse on time dan pulse off time adalah faktor yang paling penting

yang melaksanakan ciri-ciri pemesinan EDM. Parameter optimum bagi eksperimen

ini ialah current dengan tahap 1 diikuti oleh pulse on time tahap 2 dan tahap 3 pulse

off time. Ia akan menyokong dengan peratusan sumbangan menggunakan analisis of

varians (ANOVA) bagi MRR, current 62.57%, pulse on time 36.10% dengan

23.41% pulse off time. Kemudian, untuk EWR, current 57.35% dengan 25.31%

daripada pulse on time dan pulse off time 14.11%. Akhir sekali, bagi Ra peratusan

untuk current adalah 99.85%, pulse on time 17.13% dengan 0.10% pulse off time.

Oleh itu, current adalah faktor penting semasa bahan kerja melebur.

ii

ABSTRACT

Electric discharge machining (EDM) is the process for cutting hard metal and

forming deep area by arc erosion in all kind of electro conductive material. It is one

of the non-traditional machining processes that involved a transient spark discharges

through the fluid due to the potential difference between the electrode and the work

piece. EDM is most used where intricate complex shapes need to be machined in

very hard materials such as hardened tool steel. This paper presents a fundamental

study of characteristics of electrode discharge machine (EDM) that are electrode

wear ratio (EWR), material removal rate (MRR), surface roughness (Ra), and

appearance observation. The experiment was done using SODICK AQ35L EDM

machine. Design of experiment (DOE) using taguchi method was applied to design

the experimental number of trials, and analyze the significant factors that affecting

the machining characteristics for EDM process. Total of nine experiments were

conducted with each repeated three times. The results obtained from this research

shows that current, pulse on time and pulse off time were the most significant factor

effecting the EDM machining characteristics. The optimum parameters for this

experiment which are current with level 1 followed by pulse on time of level 2 and

level 3 pulse off time. It will support with the percentage of contribution using

analysis of variance (ANOVA) of MRR, current 62.57%, pulse on time 36.10% with

23.41% pulse off time. Then, for EWR, current 57.35% with 25.31% of pulse on

time and pulse off time 14.11%. Lastly, for Ra the percentage for current is 99.85%,

pulse on time 17.13% with 0.10% pulse off time. Thus, the flow of current melting

the workpiece that’s why the current was the significant factor.

iii

DEDICATION

Special dedicated to my mother

Shamsiah Binti Yusuf

My beloved father

Kamarudin Bin Mat Saman

My supportive siblings

Mohammad Amirul Asyraf Bin Kamarudin

Nur Alifah Ilyana Binti Kamarudin

Muhamad Aliff Haiqal Bin Kamarudin

For my adored friends

Suraya Laily

(Master’s Student)

And to all my relatives and friends for their supports, courage and prayers.

May Allah bless all of you

iv

ACKNOWLEDGEMENT

Alhamdulillah and thank you to Allah S.W.T. for giving me strength and ability to

accomplish this project research successfully. I would like to take the greatest

opportunity to express my sincere and gratitude to my supervisor, Dr. Mohd Amran

Bin Md. Ali for his encouragement, guidance, ideas which enlighten my curiosity,

suggestion, advice and friendship throughout the year in completing this final year

project. Besides, thanks to all the lecturers and staff of the Faculty of Manufacturing

Engineering.

In this opportunity, I would like to give my sincere gratitude to my beloved parents

and family who always pray and give the encouragement while pursuing my research

and project. Their sacrifices are never being forgotten.

My special thanks to the friend that gives support and always company me in making

and complete this project, I really thankful and appreciate it very much.

v

TABLE OF CONTENT

Abstrak i

Abstract ii

Dedication iii

Acknowledgement iv

Table of Content v

List of Tables viii

List of Figures x

List Abbreviations, Symbols and Nomenclatures xii

CHAPTER 1: INTRODUCTION 1

1.1 Background of the Project 1

1.2 Problem Statement 3

1.3 Objectives 3

1.4 Scopes 4

1.5 Outline of the Report 4

CHAPTER 2: LITERATURE REVIEW 5

2.1 EDM Machining Operations 5

2.1.1 Types of EDM Machines 7

2.1.2 EDM Die Sinking 9

2.2 EDM Machining Parameters 11

2.3 EDM Characteristics 14

2.3.1 Material Removal Rate (MRR) 14

2.3.2 Electrode Wear (EWR) 15

2.3.3 Surface Roughness (Ra) 16

2.3.4 Texture and Cracking of Craters 18

2.4 Material Workpiece 19

2.5 Types of Electrode 19

2.5.1 Copper 20

2.5.2 Graphite 20

vi

2.5.3 Tungsten Carbide 21

2.5.4 Cooper Tungsten 21

2.5.5 Iron 21

2.6 Design of Experiment (DoE) 22

2.6.1 Taguchi Method 22

2.6.1.1 Signal to Noise (S/N) Ratio 23

2.6.1.2 Response to Signal to Noise (S/N) Ratio 24

2.6.1.3 Analysis of Variance (ANOVA) 24

2.7 Summary 25

CHAPTER 3: METHODOLOGY 26

3.1 Experimental Setup 26

3.1.1 Current Experimental Setup 28

3.2 Specimen Preparation 30

3.3 Electrode Preparation 31

3.4 Experimental Parameters 32

3.5 Design of Experiment (DoE) 34

3.5.1 Taguchi Method Using Minitab English Version Sixteen 37

3.6 Summary 39

CHAPTER 4: RESULT AND DISCUSSION 40

4.1 Experimental Data 40

4.1.1 Selection of Factor Using Taguchi Method Design 40

4.1.2 Selection of Factor Level 41

4.1.3 Selection of Orthogonal Array (OA) 41

4.2 Result of the Experiment 42

4.3 Analysis of the Result 44

4.4 Analysis Result of Surface Roughness (Ra) Response 44

4.4.1 Signal to Noise Ratio Response of Ra 44

4.4.2 Signal to Noise Ratio Plot for Ra 45

4.4.3 Validation for Ra 46

4.5 Analysis of Variance (ANOVA) for Ra 47

4.6 Overall Result of Ra 50

vii

4.7 Analysis Result of Material Removal Rate (MRR) Response 51

4.7.1 Signal to Noise Ratio of MRR 52

4.7.2 Signal to Noise Ratio Plot for MRR 52

4.7.3 Validation for MRR 53

4.8 Analysis of Variance (ANOVA) for MRR 54

4.9 Overall Result of MRR 57

4.10 Analysis Result of Electrode Wear Rate (EWR) Response 58

4.10.1 Signal to Noise Ratio of EWR 58

4.10.2 Signal to Noise Ratio Plot for EWR 59

4.10.3 Validation for EWR 60

4.11 Analysis of Variance (ANOVA) for EWR 60

4.12 Overall Result of EWR 63

4.13 Surface Crater Observation 64

4.13.1 Surface Crater of the Smooth Surface 64

4.13.2 Surface Crater of the Rough Surface 65

CHAPTER 5: CONCLUSION AND FUTURE WORK 66

5.1 Conclusion 66

5.2 Future Work 65

REFERENCES 68

APPENDIXES 71

A Final Year Project Planning 71

B Full Data Obtained From Experiments 74

C Results of Surface Roughness 76

D Workpiece Surface Pictures 87

viii

LIST OF TABLES

2.1 Types of EDM machines 7

3.1 Mechanical, Physical, Electrical and Thermal properties of LM6 30

3.2 Properties of copper electrode 32

3.3 Factors and levels for the experiments based on journal 33

3.4 Factors and levels selected for the experiments 34

4.1 Factors and levels selected for experiments 41

4.2 The orthogonal array for all the combination parameter for the

effective factors

42

4.3 Result of the Experiment 43

4.4 Result of the Surface Roughness 44

4.5 Response Table for Signal to Noise Ratios of Ra 45

4.6 Validation Test of Ra 47

4.7 Mean Versus Current for Ra 47

4.8 Mean Versus Pulse On Time for Ra 48

4.9 Mean Versus Pulse Off Time for Ra 49

4.10 Result of Taguchi Method and ANOVA for Ra 50

4.11 Result of the Material Removal Rate 51

4.12 Response Table for Signal to Noise Ratios of MRR 52

4.13 Validation Test of MRR 53

4.14 Mean Versus Current for MRR 54

4.15 Mean Versus Pulse On Time for MRR 55

4.16 Mean Versus Pulse Off Time for MRR 56

4.17 Result of Taguchi Method and ANOVA for MRR 57

4.18 Result of the Electrode Wear Rate 58

4.19 Response Table for Signal to Noise Ratios of EWR 59

4.20 Validation Test of EWR 60

4.21 Mean Versus Current for EWR 60

ix

4.22 Mean Versus Pulse On Time for EWR 61

4.23 Mean Versus Pulse Off Time for EWR 62

4.24 Result of Taguchi Method and ANOVA for EWR 63

x

LIST OF FIGURES

2.1 Concept of EDM 6

2.2 Sinking Electrical Discharge Machining 10

2.3 Schematic representation of the phases of an electric discharge in

EDM and the definition of duty factor τ

11

2.4 Actual profile of single EDM pulse 13

2.5 Pulse wave form of pulse generator 13

2.6 Coordinate used for surface roughness measurement 17

2.7 Sample of surface texture and craters 18

3.1 Experimental methodology 27

3.2 EDM die sinking Sodick AQ35L Series 28

3.3 Precise Digital Balance 29

3.4 Surface Roughness Equipment 29

3.5 Digital Image Microscope 30

3.6 Aluminum Alloy LM6 Dimension 31

3.7 Electrode Dimension 32

3.8 Design of Experiment process flow 36

3.9 The factor and level design are selected 37

3.10 The Taguchi Method is selected with L9 37

3.11 The table of factor 38

3.12 The orthogonal array in Taguchi Method 38

4.1 Main Effects Plot for Signal to Noise Ratios of Ra 46

4.2 Boxplot Mean Versus Current for Ra 48

4.3 Boxplot Mean Versus Pulse On Time for Ra 49

4.4 Boxplot Mean Versus Pulse Off Tiime for Ra 50

4.5 Main Effects Plot for Signal to Noise Ratios of MRR 53

4.6 Boxplot Mean Versus Current for MRR 55

4.7 Boxplot Mean Versus Pulse On Time for MRR 56

xi

4.8 Boxplot Mean Versus Pulse Off Time for MRR 57

4.9 Main Effects Plot for Signal to Noise Ratios of EWR 59

4.10 Boxplot Mean Versus Current for EWR 61

4.11 Boxplot Mean Versus Pulse On Time for EWR 62

4.12 Boxplot Mean Versus Pulse Off Time for EWR 63

4.13 Sample 3 surface observed VIS Digital Imaging Microscope with

230 times magnification

64

4.14 Sample 8 surface observed by VIS Digital Imaging Microscope

with 230 times magnification

65

xii

LIST OF ABBREVIATIONS, SYMBOLS AND

NOMENCLATURE

A - Ampere

ANOVA - Analysis Of Variance

CNC - Computer Numerical Control

DC - Direct Current

DOE - Design of Experiment

Ea - Electrode Weight after machining

Eb - Electrode Weight before machining

EDE - Electro-Discharge Erosion

EDM - Electrical Discharge Machine

EDG - Electric Discharge Grinding

EWR - Electrode Wear Rate

HAZ - Heat Affected Zone

HB - Higher is better

Ip - Peak Current

LB - Lower is better

MRR - Material Removal Rate

NB - Nominal is best

OA - Orthogonal Array

Ra - Surface Roughness

Rq - Root- Mean Squire Average

xiii

Sil2 - Silicate

S/N - Signal to Noise

TiC - Titanium Carbide

TWR - Tool Wear Rate

V - Voltage

Wa - Material Weight after machining

Wb - Material Weight before machining

îe - Peak Current

n - Number of Reading

td - Time Delay

te - Period of Time

tm - Machining time

to - Interval of Time

toff - Pulse Off Time

ton - Pulse On Time

ue - Low Discharge Voltage

ûi - Open Circuit Voltage

μm - Micrometer

µs - Microsecond

1

This section explains the background of the area of the study, the aims and

objectives of this study, and why this study interesting and relevant to the

engineering field.

1.1 Background of the Project

Electrical discharge machine (EDM) die-sinking is an important non-traditional

manufacturing method which it known as EDM die-sinking is a process of

machining electrically conductive materials by using controlled sparks that happen

between an electrode and a work piece in the existence of a dielectric fluid. These

materials would have been difficult to machine by conventional methods, but EDM

die-sinking has made it relatively simple to machine intricate shapes that would be

impossible to produce with conventional cutting tools. In EDM die-sinking process,

the shapes of mold cavities are directly copied from that of tool electrodes, so time

consuming preparation work must be done on the fabrication of the corresponding

tool electrodes (Iqbal A. and Khan A. A.,2010).

The uses of EDM die-sinking in the production of forming tools are to produce

plastics moldings, die castings, forging dies etc., has been firmly established in

recent years. This machining process is continually finding further applications in the

metal machining industry. Although, the application of EDM die-sinking is limited to

the machining of electrically conductive work piece materials, the process has the

INTRODUCTION

CHAPTER 1

2

capability of cutting these materials regardless of their hardness and toughness (Lee

and Li, 2001).

The case study of this project are to determine the best material removal rate (MRR),

electrode wear rate (EWR), surface roughness (Ra), and texture & cracking of

craters. Using this testing, the best performance of the of machining for EDM die-

sinking can be archived when the the best combination of parameters should be

studied to produce an optimum result.

In this project, the effect of EDM die-sinking parameters such as pulse on time, pulse

off time and current on the surface integrity. The condition by using EWR, MRR,

Ra, and texture & cracking of craters will be evaluated with copper beryllium using

electrolytic copper show that usefulness of EDM die-sinking process.

The advantages of the EDM die-sinking machines are it can use to cut of any

material that is electrically conductive, burr is free when using the EDM die-sinking

process, and complex dies will can be produce by EDM die-sinking machine with

accurately, low costs and faster. It also needed the hardened tool material must be

harder than workpiece material to get the good effect and the very important is very

fine holes can be easily drilled.

3

1.2 Problem Statement

In using electrical discharge machine (EDM) die-sinking can be caused poor

performance if not choose the suitable material of the electrode and it will effected of

the test parameters such as pulse on time (ton), pulse off time (toff), voltage (V) and

peak current (Ip). Meanwhile, it also influences the surface integrity when using

EDM like electrode wear rate (EWR), material removal rate (MRR), surface

roughness (Ra), and texture & cracking of craters when it is apply on the aluminum

alloy LM6 containing silicate and titanium carbide. So that, design of experiment

(DOE) will be performed in order to obtain the optimum parameters. Besides that,

erosion of the workpiece must be maximized and the electrode must be minimized in

order to increase the machining efficiency. Therefore, studying the electrode wear

and related significant factors would be effective to enhance the machining

productivity and process reliability.

1.3 Objectives

The objectives of this project are:

a) To study the effect of machining EDM die-sinking parameters such as pulse

on time, pulse off time, voltage and current on the EDM die-sinking

characteristics of aluminium alloy LM6.

b) To evaluate machining characteristics of aluminum alloy LM6 in surface

roughness (Ra), material removal rate (MRR), electrode wear rate (EWR) and

appearance observation.

c) To optimize the machining characteristics using taguchi method and to

analyze the percentage of contribution using analysis of varice (ANOVA)

4

1.4 Scope of the Project

These projects will analysis about the various type of machining parameter relate to

the machining characteristics while EDM die-sinking process. In this process, the

material that use is silicate and titanium carbide and the electrode is copper. The

scope should be low cost and short time use to finishing the process. To analyze the

result and the data collections, the calculations is very important to calculate the

machining characteristics which are electrode wear rate (EWR) and material removal

rate (MRR). The higher friction coefficients are needed when to get surface

roughness and the presence of crater is observed under digital image microscope.

Nowadays, more knowledge about electrical discharge machine is very important. So

that, hopefully with this project can gain a lot of understanding of EDM die-sinking

and get more experience to handle and use it because EDM die-sinking broad

industrial applications. .

1.5 Outline of the report

This report is divided in five chapters as follows:

a) Chapter 1 – background of the project, problem statements, objectives of the

project and the scopes of the project.

b) Chapter 2 – literature review of EDM, machining parameters and

characteristics

c) Chapter 3 – gives information on electrode and material, testing procedure

that involve in the experiment.

d) Chapter 4 – result and analysis of the experiments.

e) Chapter 5 – summarize the results and discussion as well as conclusion of the

case study.

5

This section basically analysis of patent, journal paper, article and conference

paper to the research purpose. The similarities and differences between what

other people investigated had been taken out as well as the machine design. In

order to establish a new machining method for EDM, the research question and

purpose of each review have been evaluated.

2.1 EDM Machining Operation

Electrical Discharge Machining (EDM) is most widely and successfully applied

process in machining of hard metals or those that would be very difficult to machine

with traditional techniques. The material is removed from the work piece by the

thermal erosion process which is by a series of recurring electrical discharges

between a cutting tool acting as an electrode and a conductive work piece in the

presence of a dielectric fluid. This discharge occurs in a voltage gap between the

electrode and work heat from the discharge vaporizes minute particles of work piece

material, which are then washed from the gap by the continuously flushing dielectric

fluid (Reddy et. al. 2010) as shown in Figure 2.1.

LITERATURE REVIEW

CHAPTER 2