UNIVERSITI TEKNIKAL MALAYSIA MELAKA

EXPERIMENTAL INVESTIGATION OF STAINLESS STEEL BY

USING ELECTRICAL DISCHARGE MACHINE (EDM)

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

NUR RASHIDAH BINTI MOHMAD DAUD

BO51110098

890507-23-5122

FACULTY OF MANUFACTURING ENGINEERING

2014

UNIVERSITI TEKNIKAL MALAYSIA MELAKA

BORANG PENGESAHAN STATUS LAPORAN PROJEK SARJANA MUDA

TAJUK: EXPERIMENTAL INVESTIGATION OF STAINLESS STEEL BY USING

ELECTRICAL DISCHARGE MACHINE (EDM)

SESI PENGAJIAN: 2013/14 Semester 2 Saya NUR RASHIDAH BINTI MOHMAD DAUD

Mengaku membenarkan Laporan PSM ini disimpan di Perpustakaan Universiti Teknikal Malaysia Melaka (UTeM) dengansyarat-syarat kegunaan seperti berikut:

1. Laporan PSM adalah hak milik Universiti Teknikal Malaysia Melaka dan penulis. 2. Perpustakaan Universiti Teknikal Malaysia Melaka dibenarkan membuat salinan

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: 188, KG PT NO 4,

JALAN YUSOF SEMERAH,

83600 BATU PAHAT JOHOR. Tarikh: __23/6/2014

Disahkan oleh:

Cop Rasmi:

Tarikh: _______________________

** JikaLaporan PSM ini SULIT atau TERHAD, silalampirkansuratdaripadapihakberkuasa/organisasiberkenaandenganmenyatakansekalisebabdantempohlaporan PSM iniperludikelaskansebagai SULIT atau TERHAD.

DECLARATION

I hereby, declared this report entitled “Experimental Investigation of Stainless Steel

by using Electrical Discharge Machine (EDM)” is the results of my own research

except as cited in references

Signature : ………………………………………….

Author’s Name : NUR RASHIDAH BINTI MOHMAD DAUD

Date : 23 JUN 2014

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:

………………………………

(DR LIEW PAY JUN)

i

ABSTRAK

Electrical Discharge Machining (EDM) adalah salah satu proses pemesinan termaju,

berdasarkan termo tenaga elektrik di antara bahan kerja dan elektrod. Biasanya, EDM

digunakan untuk memesin bahan yang mempunyai kekerasan yang tinggi dan bentuk yang

kompleks. Dalam kajian ini, kesan saiz mikro dan nano bagi serbuk karbon yang ditambah

kedalam bendalir dielektrik pada keluli tahan karat telah disiasat dengan menggunakan proses

EDM. Dalam eksperimen ini, SODICK AQ35L adalah model mesin EDM yang digunakan

untuk memesin bahan keluli tahan karat dengan menggunakan elektrod tembaga. Berat bahan

kerja dan elektrod telah direkodkan sebelum dan selepas eksperimen dengan menggunakan

Precise Digital Balance untuk mendapatkan material removal rate (MRR) dan tool wear rate

(TWR). Manakala bagi kekasaran permukaan bagi bahan kerja (keluli tahan karat) telah

diperiksa dengan menggunakan Mitutoyo SJ-301 surface roughness tester dan sela bunga api itu

diperiksa dengan menggunakan stereo microscopic. Ia mendapati bahawa apabila saiz nano

bagi serbuk karbon yang dicampur kedalam cecair dielektrik dan menghasilkan nilai material

removal rate (MRR) yang lebih tinggi, tool wear rate (TWR) yang lebih rendah, dan

kekasaran permukaan yang lebih licin yang boleh didapati berbanding dengan saiz mikro bagi

serbuk karbon yang dicampurkan kedalam cecair dielektrik. Penambahan saiz nano serbuk

juga, boleh mengurangkan kekuatan penebat cecair dielektrik dan menghasilkan sela bunga

api yang lebih besar.

ii

ABSTRACT

Electrical Discharge Machining (EDM) is one of the advanced machining processes, based

on thermo electric energy between the workpiece and tool. Normally, EDM used to machine

high hardness materials and complex shape. In this research, the effect of the micro and nano

size of carbon powder additive into dielectric fluid on the stainless steel was investigated by

using EDM process. In the experiment, EDM machine model SODICK AQ35L was used to

machine stainless steel material by using copper electrode. The weight of the workpiece and

electrode were recorded before and after the experiment by using Precise Digital Balance in

order to obtain Material Removal Rate (MRR) and Tool Wear Rate (TWR). While, the

surface roughness of the workpiece (stainless steel) was examined using Mitutoyo SJ-301

surface roughness tester and the spark gap was examined using stereo microscopic. It was

found that when nano size of carbon powder was mixed into the dielectric fluid, higher

material removal rate (MRR), lower tool wear rate (TWR), and smoother surface roughness

can be obtained compared to the micro size of carbon powder. Addition of nano size of

powder also can reduce insulating strength of dielectric fluid and result to a bigger spark gap.

iii

DEDICATION

First and foremost, I would like to express my greatest appreciation to Universiti Teknikal

Malaysia Melaka for giving me the opportunity to undergo my final year “Projek Sarjana

Muda”. A special thank you also goes to my supervisor Dr. Liew Pay Jun for her dedication

and guidance during the period of undergoing my project and also to technician En Hanafiah

for his guidance. Last but not least, I want to thank my mom and dad for their support as well

as to all my friends Fazreena Binti Mohamad Noor Adami and Muhammad Nur Syafiq bin

abdul Rahman who never give up encouraging me to complete this report.

Thank you,

iv

ACKNOWLEDGEMENT

Firstly, I am thankful to ALLAH S.W.T for blessing me in finishing this final year

project (FYP) with successful complete and in achieving the objectives of this project.

Hopefully, this project will be benefit to all.

In this opportunity, I would like to give my sincere gratitude to my family, Mohmad

Daud bin masro, my father, Masriah binti Abu, my mother and all of family members for

morale support, motivation and encouragement in completing this final year project and in

finishing my study in UTeM with successful

I also would like to convey my full appreciation and thankful to my supervisor, Dr

Liew Pay Jun for her guidance, supervising, and continuous support to complete my final

year project for these two semesters. She has been very helpful and always advices me

whenever there are problem in complete this project. I really appreciate every advice and

without her support, critics I could not finish this thesis as presented here.

My sincere thanks go to vocational advisor, Mr Hanafiah for his guidance for in

operating the Electrical Discharge Machine.

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

and complete this project.

v

TABLE OF CONTENT

Abstract i

Abstract ii

Dedication iii

Acknowledgement iv

Table of Content

v

List of Tables viii

List of Figures

ix

List of Abbreviation, Symbols and Nomencatures xi

CHAPTER 1 : INTRODUCTION

1.1 Background 1

1.2 Problem statement 2

1.3 Objective 3

1.4 Scope of Project 3

CHAPTER 2 : LITERITURE REVIEW

2.1 Electrical Discharge Machine (EDM) 4

2.1.1 History of EDM 6

2.1.2 Types of EDM 7

2.1.2.1 Wire Electrical Discharge Machining

(WEDM)

7

2.1.2.2 EDM die-sinking 8

2.2 Principle of EDM die-sinking 9

2.3 EDM parameters 10

2.3.1 Discharge voltage 11

2.3.2 Peak current 11

2.3.3 Pulse on time (Ton) 12

2.3.4 Pulse off time (Toff) 12

2.3.5 Polarity 13

vi

2.4 EDM characteristic 13

2.4.1 Material Removal Rate (MRR) 14

2.4.2 Tool Wear Rate (TWR) 15

2.4.3 Surface Roughness (Ra) 16

2.4.4 Spark Gap 18

2.5 Tool (Electrodes) 19

2.5.1 Selection electrode 19

2.6 Dielectric fluid 20

2.7 Flushing 21

2.8 Stainless Steel 21

2.9 Powder mixed electrical discharge machining 22

CHAPTER 3 : METHODOLOGY

3.1 Planning project 26

3.2 Specimen preparation 29

3.3 Tool preparation 30

3.4 Carbon powder 31

3.5 Machines and Measurements Equipments 32

3.5.1 EDM Die-Sinker machine 32

3.5.2 Ultrasonic 33

3.5.3 Precision digital balance 34

3.5.4 Surface roughness measurement 34

3.5.5 Stereo microscope 35

3.6 Experimental Conditions 36

CHAPTER 4 : RESULT & DISCUSSION

4.1 Result and analysis of the experiment 37

4.1.1 Material removal rate (MRR) 37

4.1.2 Tool wear rate (TWR) 40

4.1.3 Spark gap 43

4.1.4 Surface roughness (Ra) 46

vii

CHAPTER 5 : CONCLUSION AND FUTURE WORK

5.1 CONCLUSION 49

5.2 FUTURE WORK 50

REFERENCE 51

APPENDICES

viii

LIST OF TABLE

2.1 Comparison between EDM process and conventional machining

processes (milling/turning)

5

2.2 Electrode Polarities for Different Workpiece Materials 13

3.1 Material properties of stainless steel 29

3.2: Material properties of copper electrode 30

3.3 Concentration of carbon powder mixture 33

3.6 Experimental condition 36

4.1 Data of material removal rate (MRR) 38

4.2 Data of tool wear rate (TWR) 41

4.3 Data of spark gap 44

4.4 Data of surface roughness 47

ix

LIST OF FIGURE

2.1 EDM process 6

2.2 Schematic diagram of WEDM 8

2.3 Schematic diagram of EDM Die-Sinker Set-up 9

2.4 Working principle of EDM 9

2.5 Principle of EDM process 10

2.6 Pulse wave form of pulse generator 12

2.7 Different layers on EDM Surface 16

2.8 EDM surface layer for W300 ferritic steel material 17

2.9 The arimethic mean value 17

2.10 Schematic diagram of EDM for spark gap 18

2.11 Difference between electrode (Cu ZrB2 material) (a) after and (b)

before machining using EDM Die Sinking

20

2.12 Principle of powder mixed EDM 23

2.13 Micrographs of the cross section of craters for (a) kerosene and

(b) kerosene and nickel powder mixed fluid, NPMF

24

2.14 Generation mechanism of TiC layer 24

2.15 carbon nanotubes (CNT) have a straight-pin shape 25

3.1 Flow chart of methodology for chapter 1, 2, and 3 17

3.2 Flow chart of methodology for chapter 4 and 5 18

3.3 Stainless Steel Material 29

3.4 Dimension of specimen 30

3.5 Copper electrode 31

3.6 Dimension of electrode 31

3.7 Sodick AQ35L series EDM die-sinking machine 32

3.8 Sartorius Stedim (LABSONIC® P) series Ultrasonic 33

3.9 Precise Digital Balance 34

3.10 Surface roughness tester Mitutoyo SJ-301 35

3.11 Stereo microscope 35

x

4.1 Effect of the different nano and micro particles size on material

removal rate (MRR)

39

4.2 Effects of micro and nano sizes of carbon powder addition into

the dielectric fluid on tool wear rate (TWR)

42

4.3 Effects of micro and nano sizes of carbon powder addition into

the dielectric fluid on spark gap

45

4.4 Effects of micro and nano sizes of carbon powder addition into

the dielectric fluid on surface roughness

48

xi

LIST OF ABBREVIATIONS, SYMBOLS AND

NOMENCLATURE

EDM - Electrical Discharge Machining

WEDM - Wire Electrical Discharge Machining

CNC - Computer Numerical Controlled

BeCu - Beryllium Copper

CNT - Carbon nanotubes

Al - Aluminum

Si - Silicon

MRR - Material Removal rate

TWR - Tool Wear Rate

Ra - Surface roughness

- Material weight before machining

- Material weight after machining

tm - Machining time

- Tool (electrode) Weight before machining

- Tool (electrode) Weight after machining

n - Number of readings

- The diameter of the hole

- Electrodes after machining

DC - Direct current

Ra - Surface roughness

DA - Dimensional accuracy

SR - Surface finish

V - Voltage

A - Ampere

xii

Ton - Pulse on time

Toff - Pulse off time

μsec - Micro second

μm - Micrometer

g/min - Gram per minute

mm - Millimeter

g/l - Gram per liter

% - Percentage

E Young modulus

1

This chapter describes the introduction of the experiment. In this experiment, the

effect of micro and nano size of carbon powder as an additive into dielectric fluid

were compared by using Electrical Discharge Machining (EDM). This chapter

includes the background, problem statement, objective and scope of this study.

1.1 Background

Electrical Discharge Machine (EDM) is most important acknowledge technologies in

manufacturing industries since many complex shapes can be machining by using a

simple shaped of the tool electrode. Electrical Discharge Machining (EDM) is an

advance manufacturing process. This process used to remove the material by

controlled erosion from a series of electric sparks between an electrode and

workpiece with the existence of dielectric fluid. The electrode may be considered as

the cutting tool (Nikhil et al, 2012). Currently, EDM is an extensive technique used

in the industry for machine electrically conductive and difficult materials for

manufacturing of mould, die, automotive, aerospace and surgical components.

(Soumyakant et al, 2012).

The latest developments in the field of EDM have progressed due to the growing

application of EDM process. other than that, the challenges being faced in the

modern manufacturing industries, from the development of new materials that are

hard and difficult to machine such as tool steels, composites, ceramics, stainless

steels, super alloys, carbides, heat resistant steel and other being widely used in die

INTRODUCTION

CHAPTER 1

2

and mould making industries need the high precision, complex shapes and high

surface finish (Ayush, 2012).

The material used in this experiment is stainless steel due to its widely used in

industrial applications. It has excellent material properties primarily by their

corrosion resistance, high strength and ductility (Sidda et al, 2010). At the present,

applications of stainless steel are widespread in industries such as food processing

equipment, cryogenic vessels, gutters, brewing equipment, downspout and flushing

and components for chemical environment.

Additive powder into dielectric fluid is one of the new innovations in EDM process.

According Ahsan et al. (2012), when the powder additive into dielectric fluid, charge

powder are speeded up by the electric field and act as conductors and powder gather

in clusters. The chain formation by interlocking which help to form bridging

networks between workpiece and tool which caused early explosion or spark. The

good electrical conductivity of powder helps to increase the discharge gap between

the workpiece and tool and can be increase the insulating strength of the electric fluid

and also improved EDM machibility (Soumyakant et al, 2012). In this situation may

be occur multiple discharges, it can lead to reduce of the crater size on the surface of

workpiece. In turn, might be obtain a better surface finish compare than without

powder additive powder into dielectric fluid (Liew et al, 2013).

1.2 Problem statement

Electrical Discharge Machining (EDM) is a machining method used for hard metals

or those that would be impossible to machine with traditional techniques. Previously,

powder has been mixed into the dielectric fluid to improve the machining efficiency

of EDM. However, to date a comparison between the sizes of carbon powder on the

stainless steel has not been carried out yet. Therefore the main aim of this study is to

compare the effect of sizes of carbon powder on the material removal rate (MRR),

tool wear rate (TWR), surface roughness (Ra), and spark gap.

3

1.3 Objective

The objectives of this project are:

1 To compare the effect of micro and nano powders additive by using conventional

electrical discharge machine.

2 To investigate the effect of carbon powder concentration on material removal rate

(MRR), tool wear rate (TWR), surface roughness and spark gap of stainless steel

by using EDM.

1.4 Scope of Project

This project was focused on the comparison between the sizes of carbon powder on

the stainless steel by using EDM. The sizes of the carbon powder were micro and

nano (200-300µm and 40nm). In this process, the material that has been used is

conductive material, which is stainless steel. The material for the tool is copper.

Carbon powder was added into the dielectric fluid. The effect of micro and nano of

carbon powder on the material removal rate (MRR), tool wear rate (TWR), surface

roughness (Ra) and spark gap was investigated.

4

Basically, literature review is one of the scope studies. Literature review serves as a

guide to conduct this analysis. It will provide a variety of information about the

electrical discharge machine. In addition, it also provides information to conduct all

operations. Various references have been made in this literature review, which are

research journals, books, conference online or printed article.

2.1 Electrical Discharge Machine (EDM)

Electrical discharge machining (EDM) is an advance manufacturing processes. EDM

used most widely and successfully applied in manufacture geometrically the complex

or process in fact to manufacture hard metals or those that would be very difficult in

the machine with traditional techniques (Ojha et al, 2010, Soumyakant et al, 2012

and Sidda et al, 2010).

Mustafa et al. (2011) proved the EDM process also can be compared with other

conventional machining processes like milling and turning as shown in Table 2.1.

This comparison performed in terms of contact between workpiece and cutting tool,

force, tool or workpiece rotation, tool or workpiece conductive and material removal

method. EDM is the fourth most popular machining method at present, which is

milling, turning, grinding, and drilling.

LITERATURE REVIEW

CHAPTER 2

5

Table 2.1: Comparison between EDM process and conventional machining processes

(milling/turning) (Mustafa et al, 2011).

CHARACTERISTIC MILLING/TURNNG EDM

Contact between work piece and

tool Yes No

Force Yes No

Tool or work piece rotation Yes Not Normal

Tools or work piece conductive Not required Required

Material removal rate Shear Melt or Vaporize

Electrical discharge machining (EDM) is an advance manufacturing processes. EDM

used most widely applied in manufacture geometrically the complex or process in

fact to manufacture hard metals or those that would be very difficult in the machine

with traditional techniques (Ojha et al, 2010, Soumyakant et al, 2012 and Sidda et al,

2010).

Mustafa et al. (2011) proved the EDM process also can be compared with other

conventional machining processes like milling and turning as shown in Table 2.1.

This comparison performed based on contact between workpiece and cutting tool,

force, tool or workpiece rotation, tool or workpiece conductive and material removal

method and others. At present, EDM is one of popular machining method from

fourth machining method which is milling, turning and grinding.

6

Figure 2.1: EDM process (Mahendran et al, 2010)

However, EDM has been replacing the traditional machining operations like milling,

drilling, and other operations. Currently, EDM machining being a selection

throughout the world in manufacturing industries. EDM is can do to machining

geometrically complex or hard material components, high accuracy and difficult to

machine such as heat resistant steels, composites, super alloys, ceramics, heat treated

tool steels, carbides, heat resistant steels and others. According to Shailesh (2010),

EDM was being used in application of die and mold, nuclear industries, aerospace,

medical and surgical, aeronautics, sports, instruments, optical and others application.

2.1.1 History of EDM

The history of EDM machining techniques discovered in early 1770s when it was

discovered by an English Scientist is Joseph Priestly and found the erosive effect of

electrical discharges or sparks. However, this technique is used but has some

problems which is EDM Machining was very not accuracy and riddled with failures

(Shailesh, 2010).

While in the 1949 at the Moscow University, be found two Russian scientists are Dr.

B.R. Lazarenko and Dr. N.I. Lazarenko to develop a controlled process of machining

7

for difficult metals to machining by vaporizing material from the surface of metal.

Then in the 1950’s research about resistance capacitance type of power supply at

EDM system.

According to Shailesh (2010), at mid 1970s, commercially developed Wire EDM is

one of the techniques being selection in the industry to helped shape the metal

working industry. At 1980's a computer numerical controlled (CNC) EDM was

introduced in USA. Other than that many research have be done to improve in many

aspect such as improve the quality on surface, material removal rate by using

different cutting tool or parameters, improvement the spark gap by using different

dielectric fluid and other research (Ho et al, 2003 and Pawade et al, 2013).

2.1.2 Types of EDM

There are two main types of EDM, which are Wire Electrical Discharge Machining

(WEDM) and EDM die-sinking. Both of them are very suitable for applications in

automotive stamping dies, tools, medical component and body aircraft components.

This is caused by both of them can produce small size and high accuracy part well as

large items.

2.1.2.1 Wire Electrical Discharge Machining (WEDM)

WEDM is referring to wire electrical discharge machining. The WEDM used for

complex shapes, which have sharp edges that are very difficult to machining

processes. WEDM also used for high precision machining of all types of conductive

materials. The suitable material in the WEDM process is metals, metallic alloys,

graphite, or even some ceramic materials and other of any hardness.

Besides that, WEDM used a continuous wire as a substitute electrode. Spark

generated from the electrode wire side surface to the workpiece (Figure 2.2). The

wire is controlled by a computer numerical control (CNC). It is due allows

8

programming a path for the wire to travel along sort of like a super precision

bandsaw. The diameter wire range from 0.0120 to 0.0008 inches (Singh et al, 2009

and Bo et al, 2009).

Figure 2.2: Schematic diagram of WEDM (Bo et al, 2009)

2.1.2.2 EDM die-sinking

The EDM die sinking is shown in Figure 2.3. According to Soumyakant et al.

(2012), EDM die-sinking processes also know as nontraditional process where the

tool does not contacts the workpiece. It is also refers to spark machining, spark

eroding, burning, is a manufacturing process to make the profile shape of workpiece

is obtain using electrical discharge. The material removal from the workpiece occurs

by a series of rapidly repeated discharge between electrode and workpiece, separated

by dielectric liquid and subjected to an electric voltage.