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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 :
viii
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
xii
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
xiv
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
xv
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
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