Assessment Of Wire EDM Parameters On Stainless Steel.

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UNIVERSITI TEKNIKAT MATAYSIA METAKA

TAJUK:

"ASSESSMENT OF WIRE EDM PARAMETERS ON STAINLESS STEEL"

SESI PENGAJIAN:

2008/2009 Semester 2

Saya MOHD FITRI BIN JAMALUDIN

mengaku membenarkan laporan PSM ini disimpan di Perpustakaan Universiti Teknikal Mataysia Melaka (UTeM) dengan syarat-syarat kegunaan seperti berikut:

1. Laporan PSM / tesis adalah hak mitik Universiti Teknikat Mataysia Metaka dan penutis.

z. Perpustakaan Universiti Teknikal Mataysia Metaka dibenarkan membuat satinan untuk tujuan pengajian sahaja dengan izin penutis.

3. Perpustakaan dibenarkan membuat salinan laporan PSM / tesis ini sebagai bahan pertukaran antara institusi pengajian tinggi.

4. .Sita tandakan ({)

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NO4, JALAN PERDANA 4/7, TAMAN PUCHONG PERDANA,

47100 PUCHONG, SELANGOR.

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T a r i k h : 1 4 lc t I a 1 Tarikh: t L \ -y -ol SULIT

TERHAD

TIDAK TERHAD

(Mengandungi maktumat yang berdarjah kesetamatan atau

kepentingan Malaysia yang termaktub di dalam AKTA RAHSIA RASMI 1e721

(Mengandungi maklumat TERHAD yang tetah ditentukan oteh organisasi/badan di mana penyetidikan dijatankan)

* Jika taporan PSM ini SULIT atau TERHAD, sila lampirkan surat daripada pihak organisasi berkenaan dengan menyatakan sekali sebab dan tempoh tesis ini pertu dikelaskan sebagai SULIT atau TERHAD.

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DECLARATION

I hereby declare that this report entitled “ASSESSMENT OF WIRE EDM PARAMETERS ON STAINLESS STEEL” is the result of my own research except as

cited in the references.

Signature :

Author’s Name : MOHD FITRI JAMALUDIN

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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 (Faculty of Manufacturing Engineering). The members of the supervisory

committee are as follow:

DR BAGAS WARDONO

(Main Supervisor)

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iii

ABSTRACT

The optimum selection of manufacturing conditions is very important in manufacturing processes. This research presents the surface roughness, tolerance and machining time analysis using a wire cut machine Mitsubishi Ra 90 series. The materials used are stainless steel 304. This research is mainly focused on aspects related to surface quality, tolerance and machining time, which are one of the most important parameters form the point of view of selecting the optimum condition of process. The investigated machining parameters were voltage gap, peak current, wire tension and wire speed. Design of Experiment method analysis was used to find out the parameters affecting surface roughness, tolerance and machining time. The surface roughness of the sample has been measured by using Profilometer SJ-301 tester, tolerance measurement will be performed using micrometer and machining time will be taken using digital watch.

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ABSTRAK

Pemilihan optimum terhadap keadaan pengeluaran adalah sangat penting didalam proses pembuatan. Kajian ini merangkumi analisis terhadap permukaan selepas pemesianan, had terima dan masa pemotongan dengan menggunakan mesin Mitubishi Ra 90 series. Bahan kerja yang digunakan adalah stainless steel 304. Kajian ini kebanyakkannya tertumpu pada aspek yang berkaitan dengan kualiti permukaan, had terima dan masa pemotongan dimana adalah salah satu daripada parameter yang penting dalam membentuk sudut pandangan pemilihan keadaan proses yang optimum. Parameter pemesinan yang dikaji adalah jarak voltan, arus puncak, ketegangan wayar dan kelajuan wayar. Kaedah analisis rekabentuk eksperimen digunakan untuk mengetahui parameter yang mempengaruhi permukaan selepas pemesinan, had terima dan masa pemesinan. Permukaan selepas pemesinan akan diukur menggunakan Profilometer SJ-301, had terima diukur menggunakan micrometer dan masa pemotongan diambil menggunakan jam digital.

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DEDICATION

This is my special dedication to my parent En. Jamaludin Bin Rejab and Pn.Hamidah Binti Hamidon for their support for my study at UTeM. Also thanks to my PSM Supervisor, Dr. Bagas Wardono for guide me for this project and I’ll not forget my entire classmate and lecture for help me so much. Thank you

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ACKNOWLEDGEMENT

Alhamdulillah, thank to Allah the Almighty God for giving me strength and patience to work on this Final Year Project Report.

I would like to take this opportunity to express my sincere and deepest gratitude to my Project Supervisor; Dr. Bagas Wardono for his guidance and opinion in the cause of completing this report.

My greatest thanks to my beloved family for their prayers, support, and encouragement to me for throughout this entire period of these Final Year Project 1 and 2. I would like to thanks, Dean of Faculty of Manufacturing Engineering, University Technical Malaysia, Melaka, my academic supervisor, and to all the lectures in the faculty.

I also would like to convey my biggest thanks to all FKP technicians for supporting me throughout my project especially Mr. Khairul Affendi. The knowledge and experience I gained from you all will not be forgotten.

I’m also obliged to everyone who had directly and indirectly involve through

contributions of ideas, as well as materials and professional opinions.

Last but not least, all my friends out there for their moral support and valuable help that they have provided me throughout my project.

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TABLE OF CONTENT

Declaration i

Approval ii

Abstract iii

Abstrak iv

Dedication v

Acknowledgement vi

Table of Content ix

List of Tables x

List of Figures xii

List of Abbreviations xiii

CHAPTER 1 1

INTRODUCTION 1

1.1 Project Background 2

1.2 Problem Statement 2

1.3 Objective 3

1.4 Scope 3

CHAPTER 2 4

LITERATURE RIVIEW 4

2.1 WEDM Process 4

2.1.1 Wire EDM 5

2.1.2 Spark Generator 7

2.1.3 Dielectric System 8

2.2 WEDM Machine 8

2.2.1 Process Capabilities 9

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viii

2.3 Material 11

2.3.1 Mechanical Properties 12

2.3.2 Corrosion and Heat resistant 13

2.4 Surface Roughness 13

2.4.1 Definition of Surface Roughness 13

2.4.2 Terminology of Surface Roughness 14

2.4.3 Profilometer 15

2.5 Previous Research 16

CHAPTER 3 19

METHODOLOGY 19

3.1 Design of Experiment (DOE) 20

3.1.1 Definition of Design of Experiment 20

3.1.2 Importance of DOE 20

3.1.3 Full Factorial Design 21

3.1.4 Methodology for DOE 22

3.2 Part Design 24

3.3 Machining Parameters 26

3.4 Experiment Setup 29

3.5 Analysis 30

3.5.1 Surface Roughness Measurement 30

3.5.2 Procedure to measure surface roughness using Profilometer Tester 32

3.5.3 Tolerances 34

3.5.4 Machining Time 36

3.5.5 Data Analysis 36

3.6 Flow Chart 37

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CHAPTER 4 42

RESULT AND DISCUSSION 42

4.1 Introduction 42

4.2 Quantitative Analysis 42

4.2.1 Quantitative Analysis on Surface Roughness (Ra) 44

4.2.2 Quantitative Analysis on Machining Time 48

4.2.3 Quantitative Analysis on Tolerance 52

4.3 Qualitative Analysis 55

4.3.1 Surface Quality 55

4.3.2 Machining Time Analysis 58

4.3.3 Tolerance Analysis 58

CHAPTER 5 60

CONCLUSION AND RECOMMENDATIONS 60

5.1 Conclusion 60

5.2 Recommendations For Further Study 61

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LIST OF TABLES

2.1 Chemistry % by weight 11

2.2 Room-Temperature Mechanical Properties and Typical 12 Application of Selected Annealed Stainless Steel

2.3 Mechanical Properties for Stainless Steel 304 12 3.1 Number of Runs for 2k Full Factorial Design 21 3.2 High and Low value set up 26 3.3 The arrangement of the high and low value using 2k Factorial 27 3.4 The data for the experiment use Stainless Steel 304 28

3.5 Gantt chart For PSM 1 39

3.6 Gantt Chart for PSM 2 41

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LIST OF FIGURES

2.1 WEDM process 5

2.2 Zinc Coated EDM wire 6

2.3 Wire-cut sparking area 7

2.4 Ra90 Series 9

2.5 Standard terminology 15

2.6 Profilometer Surface roughness Tester 16

3.1 Plan for DOE 22

3.2 Dimension the part with multi view 24 3.3 Part Design after WEDM cutting 25

3.4 Final part to analysis 25

3.5 Measuring direction for right side piece 31 3.6 Measuring direction for left side piece 31 3.7 Use a block to support the workpiece 33

3.8 Printing the result 33

3.9 Width of sample from isometric view 33 3.10 Width of sample from top view 34

3.11 Micrometer 35

3.12 Flow Chart for Research 37

4.1 Normal Probability plot for surface roughness 44 4.2 Pareto Chart for Surface Roughness 45 4.3 Main Effect Plot for Surface Roughness 45 4.4 Interaction Plot for Surface Roughness 46 4.5 Cube Plot for Surface Roughness 47 4.6 Surface Plot Ra vs Current, Voltage Gap 47 4.7 Normal Probability Plot for Machining Time 48

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4.8 Cube Plot for Machining Time 49 4.9 Main Effect Plot for Machining Time 49 4.10 Interaction Plot for Machining Time 50 4.11 Cube Plot for Machining Time 51 4.12 Surface Plot for Machining Time vs Current, Voltage Gap 51 4.13 Normal Probability for Tolerance 52 4.14 Pareto Chart for Tolerance 53 4.15 Main Effect plot for Tolerance 53 4.16 Interaction Plot for Tolerance 54 4.17 Texture for rough surface 55 4.18 Texture for smooth surface 55 4.19 The finishing plate after machining 57

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xiii

LIST OF ABBREVIATIONS

EDM - Electrical Discharge Machining WEDM - Wire Electrical Discharge Machining CNC - Computer Numerical Control

AT - Automatic Wire Threading DOE - Design of Experiment ANOVA - Analysis of Variance

SEM - Scanning Electron Microscope EDS - Energy Dispersive Spectrometer

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CHAPTER 1 INTRODUCTION

Electrical Discharge Machining, EDM is one of the most accurate manufacturing processes available for creating complex or simple shapes and geometries within parts and assemblies. The main limitation of EDM is that it can only cut materials that are electrically conductive. The EDM process is commonly used in the tool and dies industry for mold-making, however in recent years EDM has become an integral part for making prototype and production parts.

There are two types of EDM processes, namely wire and die sinker. Wire EDM uses a metal wire as the tool electrode. It can generate two or three dimensional shapes on the workpiece for making punch dies and other mechanical parts. Die sinker are generally used for complex geometries where the EDM machine uses a machined graphite or copper electrode to erode the desired shape into the part or assembly.

In this research, wire EDM is chosen for improvement the performance in industries. The research for WEDM remains going on because of shortage information about WEDM machining. The most important performance measures in wire EDM are surface finish and tolerance.

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1.1 Project Background

Wire Electrical Discharge Machining (WEDM) is used primarily for cutting shapes through a selected part and assembly. A very thin moving wire serves as the electrode to cut the material that follows a programmed path. WEDM making tools and dies with the highest degree of dimensional accuracy and surface finish quality.

Surface roughness is one of important thing in manufacturing when the product has completed WEDM process. Various investigation and experiment have been made to further improvement the surface roughness in WEDM. The main focus for this research is to determine the dependency of the surface roughness and tolerance obtained on the machining parameters. The material used in this project is stainless steel and an experiment with WEDM will be performed using different parameters.

WEDM is a high cost machining because it required parameters to be set correctly to get a good surface roughness. WEDM can provide a good accuracy and surface quality as compared with other machining process. The WEDM has become a mature technology but the researches and improvement of the process are still going on especially in surface roughness.

1.2 Problem Statement

WEDM is a rapidly-growing machining method used for high-precision metallic cutting of hard materials. The published papers available now do not provide specific parameter setting and material for various machining conditions. Since WEDM is used in industries, the machining parameters need to be set for optimum machining with the knowledge of the effect of the machining parameters on the surface roughness of the process, as a result of the experimental study.

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In this study, the influence of voltage gap, peak current, wire speed and wire tension on main cutting force component is investigated.

1.3 Objective

The main objectives of this study are as the following:-

 To gain basic knowledge on WEDM machining.

 To know basic principle of WEDM machine.

 To study the importance of WEDM parameter in machining process.

 To investigate the WEDM parameter towards the result in term of surface roughness and the resulting tolerance.

 To implement design of experiment (DOE) in order to determine the significant of the parameters studied.

1.4 Scope

The main focus of this project is study WEDM process on stainless steel which will cover four parameters on cutting condition and analyze the surface roughness, resulting tolerance and time machining. The parameter considered includes the peak current, voltage gap, wire tension and wire speed. For the cutting tool, the material used is brass wire 0.25mm and the thickness of material is 5mm.

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CHAPTER 2 LITERATURE RIVIEW

A literature review was conducted to gain knowledge about the wire EDM and previous researches related with this study. The following sections present discussions on topics related with WEDM process, such as the concept of WEDM technology, the machining parameters, and the material used. At the end of the chapter, several results of previous study are presented.

2.1 WEDM Process

WEDM process is similar with contour cutting using a band saw, except that a slowly moving wire travels along a prescribed path, cutting the workpiece. The wire-cut process uses water as its dielectric with the water's resistivity and other electrical properties carefully controlled by filters and de-ionizer units. The water also serves the very critical purpose of flushing the cut debris away from the cutting zone. Flushing is an important determining factor in the maximum feed rate available in a given material thickness, and poor flushing situations necessitate the reduction of the feed rate.

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WEDM is a process for eroding and removing material using the heat created by a transient action of electric sparks between electrically conductive materials. This process is achieved by applying consecutive spark discharges between a workpiece and an electrode immersed in a dielectric liquid and separated by a small gap. Eroded particles are then flushed away by the dielectric fluid. The result of this process is that each discharge leaves a small crater on both the workpiece and the electrode. This crater affects final surface quality [1].

Figure 2.1: WEDM process [13].

2.1.1 Wire EDM

Wire is an important component in WEDM machining. EDM wire is used as electrode to generate spark erosion between the wire and the workpiece. The wire is usually made of brass, cooper, tungsten, or molybdenum. The wire diameter is typically about 0.30 mm for roughing cuts and 0.20 mm for finishing cuts. The wire is electrically charged at very high voltage and cut the material. The wire passes from one spool to another and is guided by an upper and lower guide as it cuts.

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Brass wire was the first engineered wire for WEDM. These brass manufacturers discovered that the addition of zinc (zinc + copper = brass) improved cutting performance and speed when compared to the copper in several ways. During the cutting process, the zinc in the brass wire actually boils off, which helps cool the wire and delivers more usable energy to the work zone. Brass wire is available in different strengths and properties, including elongation, electrical conductivity and alloy mixture. Zinc-coated wires are available with copper or brass cores.

Brass wire is available in different tensile strengths and properties, including:

 Elongation: amount of stretch before breaking

 Electrical Conductivity: rated as a percentage of copper, which is rated at 100  Alloy Mixture: some brass wires also include small amounts of other metals

such as aluminum or magnesium to improve tensile strength or performance [2].

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2.1.2 Spark Generator

One of the central elements of any spark erosion machine is the generator, which supplies the necessary working energy. The spark generator has the function voltage values with the relevant waveforms required for the erosion process and controls the erosion gap. It is extremely important for the gap between the wheel electrode and the workpiece to be kept constant. In order to achieve the required surface finish values, the gap should be kept as small as possible. Currently, the computer-aided spark generators are used to control the spark.

Wire cut sparking occurs between the side and machined surfaces of the workpiece. Spark length is set by the machine controls. The sparking area consists of only the front 180º of the electrode diameter as it progresses into the cut. A clearance equal to the spark length is machined on each side of the wire electrode. This side clearance is the spark overcut. The total width of the machined opening consists of the electrode diameter, plus two times the spark length. The total width of the machined opening is the kerf [3].

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2.1.3 Dielectric System

Deionizer water is the dielectric used for the wire-EDM process. Deionizer water used for four reasons: low viscosity, high cooling rate, high material removal rate and no fire hazard. The small cutting gap used with wire EDM mandates that a low-viscosity dielectric be used to ensure adequate flushing. Water meets this creation. Water can also move heat from the cutting area much more efficiency than conventional dielectric oils. More efficient cooling results in extremely thin recast layers [4].

The dielectric water must also provide the optimum conditions for the creation of an electrical field as quickly as possible in order to maintain the shield of deionizer water between the wire and the workpiece. A filter is used to remove the suspended solids and a resin is used to control the electrical conductivity of the water. A cooler keeps the liquid at a constant temperature to maintain machine accuracy [1].

2.2 WEDM Machine

In WEDM machine, many type and various machine has been used currently in industries. Most WEDM machine today is CNC controlled tools. The modern wire EDM machines rely solely upon computers to guide the wires to cut away only the metal that needs to be removed.

There are two major components required for the WEDM machine, which is the wire used to remove the metal in order to shape the product being manufactured and the metal being worked is commonly inserted and in a tub of fluid. These two components are important to checking before starting the process cutting to avoid any problem happen.

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In this study, RA90 series machine is used for the experiment. RA90 Series is a non-submerged entry level wire EDM with or without AT unit providing high machining speeds at a low-cost.

Figure 2.4: Ra90 Series

2.2.1 Process Capabilities

Wire-EDM is a specialized process that is capable of machining electrically conductive workpieces to produce fine finishes, extremely high accuracies and cut edges that have a smooth, matte finish [4].

Many wire-EDM machines are available with positioning resolution of 0.001mm (0.000040 in.) and can routinely obtain accuracies of ±0.007mm. With special care, accuracies of ±0.0025mm over 152mm (±0.0001 in. over 6 in.) are possible. However to achieve such results, care must be taken to ensure the uniformity of the wire diameter, and the temperature and resistivity of the dielectric must be closely controlled [4].

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CHAPTER 2 LITERATURE RIVIEW

2.1 WEDM Process

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Figure 2.1: WEDM process [13].

2.1.1 Wire EDM

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Brass wire is available in different tensile strengths and properties, including:

 Elongation: amount of stretch before breaking

 Electrical Conductivity: rated as a percentage of copper, which is rated at 100  Alloy Mixture: some brass wires also include small amounts of other metals

such as aluminum or magnesium to improve tensile strength or performance [2].

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2.1.2 Spark Generator

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2.1.3 Dielectric System

2.2 WEDM Machine

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In this study, RA90 series machine is used for the experiment. RA90 Series is a non-submerged entry level wire EDM with or without AT unit providing high machining speeds at a low-cost.

Figure 2.4: Ra90 Series

2.2.1 Process Capabilities

Assessment Of Wire EDM Parameters On Stainless Steel.

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DECLARATION

APPROVAL

ABSTRACT

ABSTRAK

DEDICATION

ACKNOWLEDGEMENT

TABLE OF CONTENT

LIST OF TABLES

LIST OF FIGURES

LIST OF ABBREVIATIONS

CHAPTER 1

INTRODUCTION

CHAPTER 2

LITERATURE RIVIEW

CHAPTER 2

LITERATURE RIVIEW

Parts

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Dukungan

Links

Assessment Of Wire EDM Parameters On Stainless Steel.

T

I

tr

DECLARATION

APPROVAL

ABSTRACT

ABSTRAK

DEDICATION

ACKNOWLEDGEMENT

TABLE OF CONTENT

LIST OF TABLES

LIST OF FIGURES

LIST OF ABBREVIATIONS

CHAPTER 1

INTRODUCTION

CHAPTER 2

LITERATURE RIVIEW

CHAPTER 2

LITERATURE RIVIEW

Parts

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Process Optimization Of EDM Cutting Process On Tool Steel Using Zinc Coated Electrode Wire.

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