ANALYSIS OF THE INFLUENCE OF EDM

PARAMETERS ON SURFACE QUALITY,MRR

AND EW OF WC–CO

AMIR GHAFFARI BIN KHALID

UNIVERSITI MALAYSIA PAHANG

ANALYSIS OF THE INFLUENCE OF EDM PARAMETERS ON SURFACE

QUALITY, MRR AND EW OF WC–CO

AMIR GHAFFARI BIN KHALID

A project report submitted in partial fulfillment

of the requirements for the award of the degree of

Bachelor of Mechanical Engineering with Manufacturing Engineering

Faculty of Mechanical Engineering

Universiti Malaysia Pahang

NOVEMBER 2008

ii

SUPERVISOR’S DECLARATION

We hereby declare that we have checked this project and in our opinion this project is

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

Mechanical Engineering with Manufacturing.

Signature :

Name of Supervisor : PUAN MAS AYU BINTI HASSAN

Date :

Signature :

Name of Panel : EN. MOHAMED REZA ZALANI BIN MOHAMED

SUFFIAN

Date :

iii

STUDENT’S DECLARATION

I hereby declare that this project report entitled “Analysis of the influence of edm

parameters on surface quality, MRR and EW of WC–Co” is the result of my own

research except as cited in the references. The thesis has not been accepted for any

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

Signature :

Name : AMIR GHAFFARI BIN KHALID

ID Number : ME05028

Date :

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TABLE OF CONTENTS

TITLE PAGE

SUPERVISOR’S DECLARATION ii

STUDENT’S DECLARATION iii

DEDICATION iv

ACKNOWLEDGEMENTS v

ABSTRACT vi

ABSTRAK vii

TABLE OF CONTENTS viii

LIST OF FIGURES xi

LIST OF TABLES xiii

LIST OF SYMBOLS xiv

LIST OF ABBREVIATIONS xv

CHAPTER 1: INTRODUCTION

1.1 Project Background 1

1.2 Problem Statement 2

1.3 Objectives of project 2

1.4 Project Scopes 3

CHAPTER 2: LITERATURE REVIEW

2.1 Introduction of Electro Discharge Machining (EDM) 4

2.2 Electrical Discharge Machining (EDM) - Die Sink 4

2.3 Operation of Electro Discharge Machining (EDM) 5

2.4 Machining Parameter in EDM 6

2.4.1 Electrode 8

ix

2.4.2 Flushing 9

2.4.3 Dielectric Fluid 12

2.5 Machining characteristics 12

2.5.1 Material removal rate 13

2.5.2 Electrode Wear 13

2.5.3 Surface roughness (surface quality) 15

2.6 Tungsten carbide 15

2.7 Full factorial design 16

2.7.1 Design of Experiment 17

2.8 Test for significance of the regression model (ANOVA) 17

CHAPTER 3: METHODOLOGY

3.1 Introduction 19

3.2 Flowchart of Methodology 20

3.3 Research Design Variables 21

3.3.1 Response Parameters 21

3.3.2 Machining Parameters 21

3.3.3 Workpiece Material 22

3.3.4 Electrode Material 22

3.4 Machine and Equipment 23

3.5 Response Parameters Measurement 25

3.5.1 Material removal rate 25

3.5.2 Electrode Wear 25

3.5.3 Surface Roughness 26

3.6 Experimental plan 26

CHAPTER 4: RESULT AND DISCUSSION

4.1 Introduction 29

4.2 Experimental result 30

x

4.2.1 EDM of WC-Co 30

4.3 Analysis on Surface Roughness, Ra 33

4.3.1 Significant Effects 33

4.3.2 Surface roughness, Ra 35

4.3.3 Analysis of Variance (ANOVA) 37

4.3.4 Estimate Result at Optimum Condition 39

4.3.5 Confirmation Test 42

4.3.6 Comparison Test 43

4.4 Analysis on Material removal rate, MRR 44

4.4.1 Significant Effects 44

4.4.2 Material removal rate, MRR 46

4.4.3 Analysis of Variance (ANOVA) 48

4.4.4 Estimate Result at Optimum Condition 50

4.4.5 Confirmation Test 52

4.4.6 Comparison Test 53

4.5 Analysis on Electrode Wear, EW 54

4.5.1 Significant Effects 54

4.5.2 Electrode Wear, EW 56

4.5.3 Analysis of Variance (ANOVA) 58

4.5.4 Estimate Result at Optimum Condition 59

4.5.5 Confirmation Test 62

4.5.6 Comparison Test 63

4.6 Discussion 64

CHAPTER 5: CONCLUSION AND RECOMMENDATION

5.1 Conclusion 65

5.2 Future Work Recommendation 66

REFERENCE 67

APPENDICES 69

xi

LIST OF FIGURES

FIGURE TITLE PAGE

2.1 The Illustration and Schematic of Basic EDM System 6

2.2 Pressure flushing through electrode 10

2.3 Pressure flushing through workpiece 11

2.4 Jet flushing using multiple flushing nozzle 11

3.1 Sodick CNC EDM die sink 23

3.2 Surface roughness tester 24

3.3 Balance Machine 24

4.1 Pareto Chart of Standardized Effects; Variable: Surface Roughness, SR 34

4.2 Graph of Surface Roughness, Ra versus Pulse off Time, (µs) 35

4.3 Graph of Surface Roughness, Ra versus Voltage (V) 36

4.4 Graph of Surface Roughness, Ra versus Peak Current (A) 36

4.5 Graph of Surface Roughness, Ra, versus Pulse on Time (µs) 37

4.6 Normal Probability Residual plot to Expected Normal Value of effect, Ra 38

4.7 3-D surface plots of the data main effects of the voltage and pulse off time 39

4.8 2-D fitted surface distribution of effect between two factors 40

4.9 Observed Values versus Predicted Values plot of Ra 41

4.10 Pareto Chart of Standardized Effects; Variable: Material removal rate, MRR 45

4.11 Graph of Material removal rate,MRR versus Pulse on Time, (µs) 46

4.12 Graph of Material removal rate,MRR versus voltage(V) 47

4.13 Graph of Material removal rate,MRR versus peak current (A) 47

4.14 Graph of Material removal rate,MRR, versus Pulse off Time, (µs) 48

4.15 Normal Probability Residual plot to Expected Normal Value of effect, MRR 49

4.16 3-D surface plots of the data main effects of the voltage and pulse on time 50

4.17 2-D fitted surface distribution of effect between two factors 51

4.18 Observed Values versus Predicted Values plot of MRR 51

4.19 Pareto Chart of Standardized Effects; Variable: Electrode Wear,EW 55

4.20 Graph of Electrode Wear versus Pulse off Time, (µs) 56

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4.21 Graph of Electrode wear versus Peak current, (A) 57

4.22 Graph of Electrode Wear, EW versus voltage, (V) 57

4.23 Graph of Electrode Wear, EW versus Pulse on Time, (µs) 58

4.24 Normal Probability Residual plot to Expected Normal Value of effect, EW 59

4.25 3-D surface plots of the data main effects of the peak current and pulse on time60

4.26 2-D fitted surface distribution of effect between two factors 61

4.27 Observed Values versus Predicted Values plot of EW 61

xiii

LIST OF TABLES

TABLE TITLE PAGE

3.1 Machining Parameters 21

3.2 Workpiece material properties 22

3.3 Electrode material properties 22

3.4 Table of research parameters and their levels 27

3.5 Factors and levels for experiment design with full factorial design 28

4.1 Factors and levels for EDM of WC-Co 30

4.2 Experimental plans for EDM of WC-Co 31

4.3 Experimental results for EDM of WC-Co 32

4.4 Significant factor of surface roughness, Ra 33

4.5 The ANOVA effects of Ra with no interaction model 38

4.6 Quality Characteristics of Machining Performance of Ra 41

4.7 Confirmation test result for Ra 42

4.8 Predicted Value of Ra based on STATISTICA 42

4.9 Comparison test result of Ra 43

4.10 Significant factor of material removal rate, MRR 44

4.11 The ANOVA effect of MRR with no interaction model 49

4.12 Quality Characteristics of Machining Performance of MRR 52

4.13 Confirmation test result of MRR 52

4.14 Predicted Value of MRR based on STATISTICA 53

4.15 Comparison test result of MRR 53

4.16 Significant factor of electrode wear, EW 54

4.17 The ANOVA effect of EW with no interaction model 59

4.18 Quality Characteristics of Machining Performance of EW 62

4.19 Confirmation test result of EW 62

4.20 Predicted Value of electrode wear based on STATISTICA 63

4.21 Comparison test result of EW 63

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LIST OF SYMBOLS

% Percent

∅ Diameter

ti Pulse time

t0 Pause time

µ Micron

s Second

m Minute

mm milimeter

N Newton

A Ampere

V Volt

I Intensity

oC Degree Celsius

g Gram

t Time machining

Wb Weight of workpiece before machining

Wa Weight of workpiece after machining

α Alpha base

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LIST OF ABBREVIATIONS

EDM Electrical Discharge Machining

CNC Computer Numerical Control

Ra Surface Roughness

EW Electrode Wear

MRR Material removal rate

WC Tungsten Carbide

WC-Co Tungsten Carbide with Cobalt content

CuW Copper Tungsten

ANOVA Analysis of Variance

DOE Design of Experiment

SS Statistical Significant

EWW Weight of electrode used

WRW Weight of workpiece used

HRB Hardness Rockwell unit for soft steels

HRC Hardness Rockwell unit for steel

CLA Centre Line Average

AA Arithmetic Average