study of sharp corner cutting in wire...

UNIVERSITI TEKNIKAL MALAYSIA MELAKA

Study of Sharp Corner Cutting In

Wire EDM

Thesis submitted in accordance with the requirements of the Universiti Teknikal

Malaysia Melaka for the Bachelor Degree of Manufacturing Engineering in

Manufacturing Process

By

Muhammad Iswan bin Ismail

Faculty of Manufacturing Engineering

April 2008

KUTKM Library (Pind.2/2007)

BORANG PENGESAHAN STATUS TESIS*

JUDUL: _______________________________________________________________ _______________________________________________________________ _______________________________________________________________

SESI PENGAJIAN : _______________________

Saya________________________________________________________________

mengaku membenarkan tesis (PSM/Sarjana/Doktor Falsafah) ini disimpan di Perpustakaan Kolej Universiti Teknikal Malaysia Melaka(UTeM) dengan syarat-syarat kegunaan seperti berikut:

1. Tesis adalah hak milik Universiti Teknikal Malaysia Melaka. 2. Perpustakaan Universiti Teknikal Malaysia Melaka dibenarkan membuat salinan

untuk tujuan pengajian sahaja. 3. Perpustakaan dibenarkan membuat salinan tesis ini sebagai bahan pertukaran

antara institusi pengajian tinggi.

4. **Sila tandakan (√)

(HURUF BESAR)

SULIT

TERHAD

TIDAK TERHAD

(Mengandungi maklumat yang berdarjah keselamatan atau kepentingan Malaysia yang termaktub di dalam

AKTA RAHSIA RASMI 1972)

(Mengandungi maklumat TERHAD yang telah ditentukan

oleh organisasi/badan di mana penyelidikan dijalankan)

(TANDATANGAN PENULIS)

Alamat Tetap:

Tarikh: _______________________

Disahkan oleh:

(TANDATANGAN PENYELIA)

Cop Rasmi:

Tarikh: _______________________

* Tesis dimaksudkan sebagai tesis bagi Ijazah Doktor Falsafah dan Sarjana secara penyelidikan, atau disertasi bagi pengajian secara kerja kursus dan penyelidikan, atau Laporan Projek Sarjana Muda (PSM). ** Jika tesis ini SULIT atau TERHAD, sila lampirkan surat daripada pihak berkuasa/organisasi berkenaan dengan menyatakan sekali sebab dan tempoh tesis ini perlu dikelaskan sebagai SULIT atau TERHAD.

UNIVERSITI TEKNIKAL MALAYSIA MELAKA

FAKULTI KEJURUTERAAN PEMBUATAN

Rujukan Kami (Our Ref) : 20 Mei 2008 Rujukan Tuan (Your Ref):

Pustakawan Perpustakawan Universiti Teknikal Malaysia Melaka UTeM, Ayer Keroh MELAKA. Saudara, PENGKELASAN TESIS SEBAGAI SULIT/TERHAD - TESIS SARJANA MUDA KEJURUTERAAN PEMBUATAN (PROSES PEMBUATAN): MUHAMMAD ISWAN BIN ISMAIL TAJUK: STUDY OF SHARP CORNER CUTTING IN WIRE EDM Sukacita dimaklumkan bahawa tesis yang tersebut di atas bertajuk “Study of

Sharp Corner Cutting In Wire EDM” mohon dikelaskan sebagai terhad untuk tempoh lima (5) tahun dari tarikh surat ini memandangkan ia mempunyai nilai dan potensi untuk dikomersialkan di masa hadapan. Sekian dimaklumkan. Terima kasih. “BERKHIDMAT UNTUK NEGARA KERANA ALLAH” Yang benar,

En. Abd. Halim Hakim b. Abd. Aziz

Pensyarah, Fakulti Kejuruteraan Pembuatan 06-2332680

UNIVERSITI TEKNIKAL MALAYSIA MELAKA Karung Berkunci 1200, Ayer Keroh, 75450 Melaka Tel : 06-233 2421, Faks : 06 233 2414 Email : [email protected]

DECLARATION

I hereby, declared this thesis entitled “Study of Sharp Corner Cutting In Wire EDM” is

the result of my own research except as cited in references.

Signature : ………………………………………………………….

Author’ s Name : ………………………………………………………….

Date : ………………………………………………………….

i (a)

ABSTRACT

EDM or Electrical Discharge Machining is a process by which metal is removed by

electrical energy. A spark is discharged from an electrode vaporizing the metal. In really

EDM is a very precise method of machining and is used when a metal is too hard or

tough to machine conventionally. The experimental study presented in this paper aims to

select the most suitable cutting and offset parameter combination for the wire electrical

discharge machining process in order to get the desired surface roughness value,

dimensional and corner cutting accuracy for the machined workpieces. A series of

experiments have been performed on two types of steel material with same thicknesses.

The test specimens have been cut by using different cutting and offset parameter

combinations of the “Mitsubishi RA90” wire electrical discharge machine in the

University Technical Malaysia Melaka CNC center lab. The surface roughness of the test

pieces has been measured by using a surface roughness measuring device. The dimension

accuracy will be measured by optical comparator and digital caliper. For accuracy of

sharp corner cutting image analyzer will be used. The related tables and charts have been

prepared for material type, wire diameter and wire type. The tables and charts can be

practically used for EDM parameter selection for the desired workpiece.

i (b)

ABSTRACT

EDM atau Mesin Discas Electrik adalah satu proses di mana pemotongan logam oleh

tenaga elektrik. Satu percikan api dihasilkan daripada satu elektrod menjadi wap logam.

Dengan maksud lain EDM adalah satu kaedah pemesinan yang sangat tepat dan sesuai

digunakan bagi logam-logam yang sangat keras atau sukar untuk pemesinanan secara

konvensional. Kajian yang disampaikan di dalam laporan ini bermatlamat memilih

pemotongan yang paling sesuai dan gabungan parameter bagi mengimbangi proses

nyahcas elektrik untuk mendapatkan permukaan pemotonagan yang licin, dimensi dan

ketepatan darjah untuk sudut yang tajam bagi sesuatu hasil kerja. Satu siri ujian telah

dilakukan ke atas dua jenis bahan keluli dengan ketebalan yang sama. Spesimen-

spesimen ujian telah dipotong dengan menggunakan gabungan-gabungan parameter yang

berbeza bagi memotong dan mengimbangi nyahcas elektrik dari mesin “Mitsubishi

RA90” di dalam makmal CNC, Universiti Teknikal Malaysia Melaka. Profile permukaan

kepingan-kepingan telah diukur dengan menggunakan satu penyukat profile permukaan

bahan. Ketepatan dimensi pula akan diukur oleh pembanding optik dan angkup venier.

Untuk ketepatan pemotongan sudut tajam, mikroskop penganalisis akan digunakan.

Jadual-jadual berhubungan dan carta-carta yang akan disediakan bagi jenis bahan, jejari

elektrod dan jenis elektrod. Jadual-jadual dan carta-carta yang dihasilkan boleh dijadikan

panduan bagi pemilihan parameter untuk pemesinan EDM.

ii

DEDICATION

Specially dedicated to my beloved father, Ismail bin Osman and my mother, Wan Hasnah

binti Wan Ali and who are very concerns, understanding patient and supporting, thank

you for everything to my supervisors, En. Abd. Halim Hakim b. Abd. Aziz, my sisters,

brother and all my friends. The work and success will never be achieved without all of

you.

iii

ACKNOWLEDGEMENT

ALHAMDULLILAH, with the guidance and support I received, my final year thesis project is

now completed. I would like to express my special greatest gratitude to my supervisor, En. Halim

Hakim Abd Aziz for his valuable guidance and continuing support throughout the entire course of

my work. Truly without his guides and wisdom I would have been lost. To PSM panels Mr.

Sivarao a/l Subramonian and Dr. Ir. Thoguluva Raghavan Vijayaram, your advice and help make

my PSM more perfect and achive the objective. I also want express my sincere and deepest

gratitude to my family Aboh, Ma, Kaklong, Kokja, Udin, Anas and Amir that give me fully

support and always prays for my success.

Not to forget, my special appreciation is addressed to En. Fendi and the other FKP technician for

their technical assistance and supervision on the EDM wire cutting machine and equipment. My

deepest gratitude also goes to all the lectures in FKP for their guidance and support. Also to my

friends that support and help me from behind, thanks to all of you. Finally, last but not least, I

would like to thank any person or any side that I can’t remember that help me to finish my PSM.

All the help that you all give to me I will not forget forever.

iv

TABLE OF CONTENTS

Abstract i

Dedication ii

Acknowledgement iii

Table of Contents iv

List of Figures ix

List of Tables xiv

List of Abbreviations, Symbols, Specialized Nomenclature xv

1. 0 INTRODUCTION 1

1.1 Background 1

1.2 Problem Statements 2

1.3 Objectives of the Study 2

1.4 Scopes of the Limitation 2

1.5 Important of Study 3

1.6 Outline of Study 3

2. 0 LITERATURE REVIEWS 4

2.1 Introduction 4

2.1.1 Electro Mechanical Theory 4

2.1.2 Thermo Mechanical Theory 4

2.1.3 Thermo Electric Theory 5

2.2 Introduction of EDM 5

2.3 General History of EDM 6

v

2.4 Working Principle of EDM 7

2.4.1 Mechanical Structure 13

2.4.2 Spark Generator 13

2.4.3 Servo system 14

2.4.4 Dielectric circuit 14

2.5 Types of EDM 15

2.5.1 Die-Sinking EDM 15

2.5.2 Wire Cut EDM 20

2.5.3 Electrical discharge grinding (EDG) 17

2.5.4 Electrical discharge machining small hole 17

2.6 Wire electrical discharge machining (WEDM) 19

2.6.1 Introduction of WEDM wire cut 19

2.6.2 History of WEDM 20

2.6.3 Wire-cut Machine 21

2.6.4 Wire Cut EDM Electrodes 23

2.6.4.1 Copper Wire 25

2.6.4.2 Brass Wire 25

2.6.4.3 Zinc-Coated Wire 26

2.7 Process Factors of EDM 29

2.7.1 Electrode Material 29

2.7.2 Dielectric Fluid 30

2.8 ON time, OFF time and Ip 31

2.9 Power Source 31

2.10 Measurement Method 33

2.10.1 Material Removal Rate (MRR) 33

2.10.2 Dimensional Accuracy 34

2.10.3 Surface Finish Texture 34

2.10.3.1 Surface Roughness Measurement and Specification 35

2.10.4 Corner Radius 40

2.10.4.1 Introduction to Sharp Corner 40

2.10.4.2 Causes of Inaccuracies at Sharp Corner 41

http://www.iqsdirectory.com/wire-edm

vi

2.11 Wear Electrode 44

2.12 Workpiece Material 45

2.12.1 Mild Steel (Low carbon steel) 45

2.12.2 Aluminum 46

3.0 METHODOLOGY RESEARCH 47

3.1 Process Planning 47

3.2 Equipment 48

3.2.1 Wire Cut EDM (Model Mitsubishi RA 90) 48

3.3 Analysis Equipment 50

3.3.1 Digital Calliper 50

3.3.2 Optical Comparator 50

3.3.3 Surface Finish Analysis 52

3.3.4 Metallurgy Microscope (Image Analyzer) 53

3.4 Methodology Planning 55

3.5 Experiment Methodology 56

3.6 Gantt Chart 62

3.6.1 Task A 62

3.6.2 Task B 62

3.6.3 Task C 62

3.6.4 Task D 63

3.6.5 Task E 63

3.6.6 Task F 63

3.6.7 Task G 63

3.6.8 Task H 63

3.6.9 Task I 64

3.6.10 Task J 64

3.6.11 Task K 64

3.6.12 Task L 64

vii

4.0 RESULT 65

4.1 Setting Condition of E 932 65

4.2 Influence of Wire Tension 65

4.2.1 For Mild Steel 65

4.2.2 For Aluminum 67

4.3 Influence of Wire Speed 68



4.4 Results for Corner Radius 71



5.0 DATA ANALSIS AND DISCUSSION 76

5.1 Influence of Wire Tension 76



5.1.3 Influents of Wire Tension 89

5.1.3.1 Dimensional Accuracy 89

5.1.3.2 Effect of Wire Tension to Surface Roughness 90

5.2 Influence of Wire Speed



5.2.3 Influence of Wire Speed 105


5.2.3.2 Surface Roughness 106

5.2.3.3 Effect of Wire Speed to Corner Radius 106

5.3 Influence of Current Peak (Ip) 107

5.3.1 For Mild Steel (With Wire Tension, WT) 108

5.3.2 For Aluminum (With Wire Tension, WT) 110

5.3.3 Mild Steel (With Wire Speed) 116


5.3.3.2 Surface Roughness 117

5.3.3.3 Corner Radius 118

viii

5.4 Influence of Material 119

5.4.1 EDM Wire-Cut Machining Base on Material 123

5.4.1.1 For Mild Steel 123

5.4.1.2 For Aluminum 124

6.0 CONCLUSION AND RECOMMENDATION 125

6.1 Recommendation 130

7.0 REFERENCE 131

8.0 APPENDIX 133

ix

LIST OF FIGURES

2.1 Electric discharge machining sparking gap 7

2.2

2.3

Basic components of EDM

Sparking occurs at closest points between the electrode and

workpiece

8

9

2.4 Next spark occurs of closest points between electrode one

workpiece8g

9

2.5

2.6

Spark occurs within a column of ionized dielectric fluid

Spark ON: electrode and workpiece material vaporized

10

11

2.7 Spark OFF: vaporized cloud suspended in dielectric fluid 11

2.8 Spark-OFF: vaporized cloud solidifies to form EDM chip 12

2.9 Basic Elements of an EDM system 13

2.10 Die Sinking or penetration 15

2.11 Wire electrical discharge machining (WEDM) 16

2.12 Electrical discharge grinding (EDG) 17

2.13

2.14

2.15

2.16

2.17

Small Hole EDM Drilling

Wire electrical discharge machining (WEDM) Products

Basic wire-cut EDM machine

Basic features of wire-EDM

Wire-cut electrode wear

18

19

21

22

24

2.18 Brass electrode wire for EDM wire cut machine 25

2.19 Double-boiler principle 27

2.20 Vaporized zinc reduces electrode temperature 27

2.21 Surface characteristics 35

2.22 Surface Roughness Measuremnt 35

2.23 The Arithmetic Mean Value, Ra 36

2.24 Shows the error of corner is defined and presented 40

2.25 Show schematic representation of the wire-EDM during cutting.

Illustrates the wire deformation during a rough cut

42

3.1 Inside the EDM wire cut machine 49

http://www.iqsdirectory.com/wire-edm

x

3.2

3.3

3.4

3.5

3.6

3.7

3.8

3.9

Wire Cut EDM (Model Mitsubishi RA 90)

Digital Calliper

Optical Comperator

Surface roughness tester (Model Mitutoyo SJ 301)

Metallurgy Microscope (Image Analyzer)

Axio imager accept a wide range of high contrast objectives

Methodology Planning Flow Chart

Lab or Work Machining Flow Chart

49

50

51

52

54

54

55

56

3.10 The suitable jig is very important for the machining 57

3.11 CAD/W software 58

3.12 The dimension of the sample 58

3.13 Shows the cutting path of the materials 61

4.1 Corner radius for peak current 8 and wire speed 2 71

4.2 Corner radius for peak current 8 and wire speed 4 72

4.3 Corner radius for peak current 4 and wire tension 4 72






5.1(a) Graph Dimensional Accuracy vs Wire Tension for Ip 4 (Mild Steel) 77

5.1(b) Graph Surface Roughness vs Wire Tension for Ip 4 (Mild Steel) 77

5.1(c) Graph Corner Radius vs Wire Tension for Ip 4 (Mild Steel) 78







5.4(a) Graph Dimensional Accuracy vs Wire Tension for Ip 12(Mild

Steel)

81



xi

5.5(a) Graph Dimensional Accuracy vs Wire Tension for Ip 4

(Aluminum)

83

5.5(b) Graph Surface Roughness vs Wire Tension for Ip 4

(Aluminum)

83

5.5(c) Graph Corner Radius vs Wire Tension for Ip 4 (Aluminum) 84


(Aluminum)

84

5.6(b) Graph Surface Roughness vs Wire Tension for Ip 6 (Aluminum) 85



(Aluminum)

86




(Aluminum)

87



5.9(a) Graph Dimensional Accuracy vs Wire Speed for Ip 4 (Mild Steel) 93

5.9(b) Graph Surface Roughness vs Wire Speed for Ip 4 (Mild Steel) 93

5.9(c) Graph Corner Radius vs Wire Speed for Ip 4 (Mild Steel) 94










5.13(a) Graph Dimensional Accuracy vs Wire Speed for Ip 4 (Aluminum) 99

5.13(b) Graph Surface Roughness vs Wire Speed for Ip 4 (Aluminum) 99

xii

5.13(c) Graph Corner Radius vs Wire Speed for Ip 4 (Aluminum) 100







5.16(a) Graph Dimensional Accuracy vs Wire Speed for Ip 12(Aluminum) 103



5.17(a) Graph Dimensional Accuracy vs Peak Current, Ip (With WT) 108

5.17(b) Graph Surface Roughness vs Peak Current, Ip (With WT) 108

5.17(c) Graph Corner Radius vs Peak Current, Ip (With WT) 109

5.18(a) Graph Dimensional Accuracy vs Peak Current, Ip (With WT) 109

5.18(b) Graph Surface Roughness vs Peak Current, Ip (With WT) 110

5.18(c) Graph Corner Radius vs Peak Current, Ip (With WT) 110

5.19(a) Graph Dimensional Accuracy vs Peak Current, Ip (With WS) 111

5.19(b) Graph Surface Roughness vs Peak Current, Ip (With WS) 111

5.19(c) Graph Corner Radius vs Peak Current, Ip (With WS) 112

5.20(a) Graph Dimensional Accuracy vs Peak Current, Ip (With WS) 112

5.20(b) Graph Surface Roughness vs Peak Current, Ip (With WS) 113

5.20(c) Graph Corner Radius vs Peak Current, Ip (With WS) 113

5.21(a) Graph Dimensional Accuracy vs Wire Tension (Base on Material) 120

5.21(b) Graph Surface Roughness vs Wire Tension (Base on Material) 120

5.21(c) Graph Corner Radius vs Wire Tension (Base on Material) 121

5.22(a) Graph Dimensional Accuracy vs Wire Speed (Base on Material) 121

5.22(b) Graph Surface Roughness vs Wire Speed (Base on Material) 122

5.22(c) Graph Corner Radius vs Wire Speed (Base on Material) 122

8.1 Clamping the workpiece 133

8.2 Optical Comparator Value panel 133

8.3 Surface roughness tester 133

8.4 Edm Control Panel Screen 133

xiii

8.5 EDM Control Panel 134

8.6 Optical Comparator Image 134

xiv

LIST OF TABLES

2.1 Show appropriate wire type for different application 28

2.2 Advantage and disadvantage type of power source 32

2.3 ISO standard Ra value for common manufacturing method 38

3.1 Table for constant EDM wire cut parameters 60

3.2

3.3

4.1

Table of function and setting range for EDM wire cut constant parameter

Gantt Chart of the Project

Machining Constants Parameters

60

65

65

8.1 Table of Parameters for Mitsubishi WEDM RA Series 135

xv

LIST OF ABBREVIATIONS, SYMBOLS, SPECIALIZED

NOMENCLATURE

PS Function to set the power supply mode

V0 Main power supply voltage

OFF Pulse OFF time

SA Stabilizer A; to make machining speed will be faster

SB Stabilizer B; high value, the slower the machining will be

SC Stabilizer C; machining for finishing circuit

SE Stabilizer E; used particularly for 1st cut machining

VG Voltage Gap; to set average machining voltage used

Ip Peak Current

WS Wire Speed

WT Wire tension

1

CHAPTER 1

INTRODUCTION

1.1 Background

Machining is an importance process in manufacturing engineering. It is dividing by two

methods to say conventional machining and unconventional machining. For example of

the conventional machining are milling, drilling and lathe. According this method, the

quality of production are depend of efficiency operator, type of process is choosing and

type of material is used. Also get in certain case where the conventional machining is not

suitable to applicable. Such as an example where the shape we want to produced are

complicated. It is because to producing the complicated partial are need high cost and a

long of producing time. Furthermore in a modern technology, get a various new material

from other sources. It is shown indeed we need a new method for improvement and

upgrading the quality of metal machining. So that, to solve this problem we need

unconventional machining for exceed the weakness by unconventional machining is

better if the parameter choosing is better. It is because this method is limited for certain

parameter only. Electrical discharge machining EDM is one of the most accurate

manufacturing methods of working exceptionally hard metals and other materials that are

difficult to machine cleanly with more conventional methods. EDM is a process of

elimination that erodes or removes metal and material in the path of electrical discharges

that form an arc between an electrode tool and the workpiece until the desired part is

attained. Using this process is extremely accurate, reliable and affordable, so it is

becoming an increasingly popular choice for many companies. But refers to the demand

of the industries that need very accuracy products so the EDM process must be have an

improvement process and research time to time so it can fulfill the demand of the

industries.

2

1.2 Problem Statement

In machining process, it is very important to get optimum cutting result where it can

reduce cutting time, reduce the wear of electrode, save the operation cost, save the

material cost, perfect sharp corner cutting with high accuracy dimensional and finishing

with a good surface texture. But then, the problem will be occurs is finishing surface

texture are not good and unsatisfactory. Also for sharp corner cutting the have many

errors will occurs. In industry actually sharp corner must be avoided because of it

difficult to produce with high accuracy but the problem will occurs when the product

need the sharp corner machining. The problem also included how to find the best

machining parameter for sharp corner cutting that will be reach to the best result of sharp

corner cutting.

1.3 Objective of Study

The purposes of this study are:

(a) To study the cutting process of sharp corner

(b) To study the relationship of sharp corner angle, surface roughness and

dimensional accuracy and workpiece material.

(c) To propose the optimum condition for machining sharp corner.

1.4 Scope and Limitation

For this study, EDM wire cut (Model Mitsubishi RA 90) will be used in CNC laboratory in

UTeM. The result of this study just suitable for this EDM wire cut (Model Mitsubishi RA 90) and

not applicable to other types of EDM wire cut or other project. Overall the project is taken as long as

5 month which is started on December 2007 until April 2008. The early choice of wire electrode is

brass wire with diameter 0.25mm. The material that will be used is mild steel and aluminum with the

thickness is 10mm.

3

1.5 Important of Study

The important of this study is as follows:

(a) To fine the best method and parameters to produce the high accuracy of sharp

corner cutting using EDM wire cut machine (Model Mitsubishi RA 90).

(b) To fine the improvement method for produce good surface finish and high accuracy of

dimensional using EDM wire cut machine (Model Mitsubishi RA 90).

(c) Can reduce the damage of the material and the machine when the machining

process.

(d) Will be a reference for academic studies which is related to EDM wire cut

machining (Model Mitsubishi RA 90).

1.6 Outline of Study

Overall this report is divided into 5 chapters. For Chapter 1 is mainly describe about the

introduction which is highlight to background, problem statement, objective of study,

scope and limitation, important of study and study outline. Chapter 2 is the literature

review which in this chapter will discuss the definition and the introduction of EDM wire cut

generally includes the operation of the machine. This chapter also will discuss the characteristic

and the basic concept of EDM machining. Then, Chapter 3 is describing about methodology of

this study. This chapter will discuss the process planning, parameter of machining and types of

material. This chapter also will describe about the specification of EDM wire cut (Model

Mitsubishi RA 90) that will be uses for the study and the measurement apparatus. For Chapter 4

is result and discussion of the study observation. This chapter will compile all the result and the

result will be form into graphs to be analyzed. The result will be discussed also in this chapter.

Chapter 6 will shown the conclusion and the recommendation of the whole this project that has

been done.

study of sharp corner cutting in wire...

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