Study of Sharp Corner Cutting In Wire EDM

Transcription

1 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

2 KUTKM Library (Pind.2/2007) UNIVERSITI TEKNIKAL MALAYSIA MELAKA BORANG PENGESAHAN STATUS TESIS* JUDUL: SESI PENGAJIAN : Saya (HURUF BESAR) 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 ( ) 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) Disahkan oleh: (TANDATANGAN PENULIS) Alamat Tetap: (TANDATANGAN PENYELIA) Cop Rasmi: Tarikh: 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

3 UNIVERSITI TEKNIKAL MALAYSIA MELAKA Karung Berkunci 1200, Ayer Keroh, Melaka Tel : , Faks : fkp@utem.edu.my 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

4 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 :.

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6 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 (a)

7 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. Spesimenspesimen 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. i (b)

8 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. ii

9 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. iii

10 TABLE OF CONTENTS Abstract Dedication Acknowledgement Table of Contents List of Figures List of Tables List of Abbreviations, Symbols, Specialized Nomenclature i ii iii iv ix xiv xv 1. 0 INTRODUCTION Background Problem Statements Objectives of the Study Scopes of the Limitation Important of Study Outline of Study LITERATURE REVIEWS Introduction Electro Mechanical Theory Thermo Mechanical Theory Thermo Electric Theory Introduction of EDM General History of EDM 6 iv

11 2.4 Working Principle of EDM Mechanical Structure Spark Generator Servo system Dielectric circuit Types of EDM Die-Sinking EDM Wire Cut EDM Electrical discharge grinding (EDG) Electrical discharge machining small hole Wire electrical discharge machining (WEDM) Introduction of WEDM wire cut History of WEDM Wire-cut Machine Wire Cut EDM Electrodes Copper Wire Brass Wire Zinc-Coated Wire Process Factors of EDM Electrode Material Dielectric Fluid ON time, OFF time and Ip Power Source Measurement Method Material Removal Rate (MRR) Dimensional Accuracy Surface Finish Texture Surface Roughness Measurement and Specification Corner Radius Introduction to Sharp Corner Causes of Inaccuracies at Sharp Corner 41 v

12 2.11 Wear Electrode Workpiece Material Mild Steel (Low carbon steel) Aluminum METHODOLOGY RESEARCH Process Planning Equipment Wire Cut EDM (Model Mitsubishi RA 90) Analysis Equipment Digital Calliper Optical Comparator Surface Finish Analysis Metallurgy Microscope (Image Analyzer) Methodology Planning Experiment Methodology Gantt Chart Task A Task B Task C Task D Task E Task F Task G Task H Task I Task J Task K Task L 64 vi

13 4.0 RESULT Setting Condition of E Influence of Wire Tension For Mild Steel For Aluminum Influence of Wire Speed For Mild Steel For Aluminum Results for Corner Radius For Mild Steel For Aluminum DATA ANALSIS AND DISCUSSION Influence of Wire Tension For Mild Steel For Aluminum Influents of Wire Tension Dimensional Accuracy Effect of Wire Tension to Surface Roughness Influence of Wire Speed For Mild Steel For Aluminum Influence of Wire Speed Dimensional Accuracy Surface Roughness Effect of Wire Speed to Corner Radius Influence of Current Peak (Ip) For Mild Steel (With Wire Tension, WT) For Aluminum (With Wire Tension, WT) Mild Steel (With Wire Speed) Dimensional Accuracy Surface Roughness Corner Radius 118 vii

14 5.4 Influence of Material EDM Wire-Cut Machining Base on Material For Mild Steel For Aluminum CONCLUSION AND RECOMMENDATION Recommendation REFERENCE APPENDIX 133 viii

15 LIST OF FIGURES 2.1 Electric discharge machining sparking gap Basic components of EDM Sparking occurs at closest points between the electrode and 8 9 workpiece 2.4 Next spark occurs of closest points between electrode one 9 workpiece8g Spark occurs within a column of ionized dielectric fluid Spark ON: electrode and workpiece material vaporized Spark OFF: vaporized cloud suspended in dielectric fluid Spark-OFF: vaporized cloud solidifies to form EDM chip Basic Elements of an EDM system Die Sinking or penetration Wire electrical discharge machining (WEDM) Electrical discharge grinding (EDG) Small Hole EDM Drilling Wire electrical discharge machining (WEDM) Products Basic wire-cut EDM machine Basic features of wire-edm Wire-cut electrode wear Brass electrode wire for EDM wire cut machine Double-boiler principle Vaporized zinc reduces electrode temperature Surface characteristics Surface Roughness Measuremnt The Arithmetic Mean Value, R a Shows the error of corner is defined and presented Show schematic representation of the wire-edm during cutting. 42 Illustrates the wire deformation during a rough cut 3.1 Inside the EDM wire cut machine 49 ix

16 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 The suitable jig is very important for the machining CAD/W software The dimension of the sample Shows the cutting path of the materials Corner radius for peak current 8 and wire speed Corner radius for peak current 8 and wire speed Corner radius for peak current 4 and wire tension Corner radius for peak current 6 and wire tension Corner radius for peak current 4 and wire tension Corner radius for peak current 8 and wire tension Corner radius for peak current 6 and wire tension Corner radius for peak current 8 and wire tension (a) Graph Dimensional Accuracy vs Wire Tension for Ip 4 (Mild Steel) (b) Graph Surface Roughness vs Wire Tension for Ip 4 (Mild Steel) (c) Graph Corner Radius vs Wire Tension for Ip 4 (Mild Steel) (a) Graph Dimensional Accuracy vs Wire Tension for Ip 6 (Mild Steel) (b) Graph Surface Roughness vs Wire Tension for Ip 6 (Mild Steel) (c) Graph Corner Radius vs Wire Tension for Ip 6 (Mild Steel) (a) Graph Dimensional Accuracy vs Wire Tension for Ip 8 (Mild Steel) (b) Graph Surface Roughness vs Wire Tension for Ip 8 (Mild Steel) (c) Graph Corner Radius vs Wire Tension for Ip 8 (Mild Steel) (a) Graph Dimensional Accuracy vs Wire Tension for Ip 12(Mild 81 Steel) 5.4(b) Graph Surface Roughness vs Wire Tension for Ip 12 (Mild Steel) (c) Graph Corner Radius vs Wire Tension for Ip 12 (Mild Steel) 82 x

17 5.5(a) Graph Dimensional Accuracy vs Wire Tension for Ip 4 83 (Aluminum) 5.5(b) Graph Surface Roughness vs Wire Tension for Ip 4 83 (Aluminum) 5.5(c) Graph Corner Radius vs Wire Tension for Ip 4 (Aluminum) (a) Graph Dimensional Accuracy vs Wire Tension for Ip 6 84 (Aluminum) 5.6(b) Graph Surface Roughness vs Wire Tension for Ip 6 (Aluminum) (c) Graph Corner Radius vs Wire Tension for Ip 6 (Aluminum) (a) Graph Dimensional Accuracy vs Wire Tension for Ip 8 86 (Aluminum) 5.7(b) Graph Surface Roughness vs Wire Tension for Ip 8 (Aluminum) (c) Graph Corner Radius vs Wire Tension for Ip 8 (Aluminum) (a) Graph Dimensional Accuracy vs Wire Tension for Ip (Aluminum) 5.8(b) Graph Surface Roughness vs Wire Tension for Ip 12 (Aluminum) (c) Graph Corner Radius vs Wire Tension for Ip 12 (Aluminum) (a) Graph Dimensional Accuracy vs Wire Speed for Ip 4 (Mild Steel) (b) Graph Surface Roughness vs Wire Speed for Ip 4 (Mild Steel) (c) Graph Corner Radius vs Wire Speed for Ip 4 (Mild Steel) (a) Graph Dimensional Accuracy vs Wire Speed for Ip 6 (Mild Steel) (b) Graph Surface Roughness vs Wire Speed for Ip 6 (Mild Steel) (c) Graph Corner Radius vs Wire Speed for Ip 6 (Mild Steel) (a) Graph Dimensional Accuracy vs Wire Speed for Ip 8 (Mild Steel) (b) Graph Surface Roughness vs Wire Speed for Ip 8 (Mild Steel) (c) Graph Corner Radius vs Wire Speed for Ip 8 (Mild Steel) (a) Graph Dimensional Accuracy vs Wire Speed for Ip 12 (Mild Steel) (b) Graph Surface Roughness vs Wire Speed for Ip 12 (Mild Steel) (c) Graph Corner Radius vs Wire Speed for Ip 12 (Mild Steel) (a) Graph Dimensional Accuracy vs Wire Speed for Ip 4 (Aluminum) (b) Graph Surface Roughness vs Wire Speed for Ip 4 (Aluminum) 99 xi

18 5.13(c) Graph Corner Radius vs Wire Speed for Ip 4 (Aluminum) (a) Graph Dimensional Accuracy vs Wire Speed for Ip 6 (Aluminum) (b) Graph Surface Roughness vs Wire Speed for Ip 6 (Aluminum) (c) Graph Corner Radius vs Wire Speed for Ip 6 (Aluminum) (a) Graph Dimensional Accuracy vs Wire Speed for Ip 8 (Aluminum) (b) Graph Surface Roughness vs Wire Speed for Ip 8 (Aluminum) (c) Graph Corner Radius vs Wire Speed for Ip 8 (Aluminum) (a) Graph Dimensional Accuracy vs Wire Speed for Ip 12(Aluminum) (b) Graph Surface Roughness vs Wire Speed for Ip 12 (Aluminum) (c) Graph Corner Radius vs Wire Speed for Ip 12 (Aluminum) (a) Graph Dimensional Accuracy vs Peak Current, Ip (With WT) (b) Graph Surface Roughness vs Peak Current, Ip (With WT) (c) Graph Corner Radius vs Peak Current, Ip (With WT) (a) Graph Dimensional Accuracy vs Peak Current, Ip (With WT) (b) Graph Surface Roughness vs Peak Current, Ip (With WT) (c) Graph Corner Radius vs Peak Current, Ip (With WT) (a) Graph Dimensional Accuracy vs Peak Current, Ip (With WS) (b) Graph Surface Roughness vs Peak Current, Ip (With WS) (c) Graph Corner Radius vs Peak Current, Ip (With WS) (a) Graph Dimensional Accuracy vs Peak Current, Ip (With WS) (b) Graph Surface Roughness vs Peak Current, Ip (With WS) (c) Graph Corner Radius vs Peak Current, Ip (With WS) (a) Graph Dimensional Accuracy vs Wire Tension (Base on Material) (b) Graph Surface Roughness vs Wire Tension (Base on Material) (c) Graph Corner Radius vs Wire Tension (Base on Material) (a) Graph Dimensional Accuracy vs Wire Speed (Base on Material) (b) Graph Surface Roughness vs Wire Speed (Base on Material) (c) Graph Corner Radius vs Wire Speed (Base on Material) Clamping the workpiece Optical Comparator Value panel Surface roughness tester Edm Control Panel Screen 133 xii

19 8.5 EDM Control Panel Optical Comparator Image 134 xiii

20 LIST OF TABLES 2.1 Show appropriate wire type for different application Advantage and disadvantage type of power source ISO standard R a value for common manufacturing method Table for constant EDM wire cut parameters Table of function and setting range for EDM wire cut constant parameter Gantt Chart of the Project Machining Constants Parameters Table of Parameters for Mitsubishi WEDM RA Series 135 xiv

21 LIST OF ABBREVIATIONS, SYMBOLS, SPECIALIZED NOMENCLATURE PS V 0 OFF SA SB SC SE VG Ip WS WT Function to set the power supply mode Main power supply voltage Pulse OFF time Stabilizer A; to make machining speed will be faster Stabilizer B; high value, the slower the machining will be Stabilizer C; machining for finishing circuit Stabilizer E; used particularly for 1 st cut machining Voltage Gap; to set average machining voltage used Peak Current Wire Speed Wire tension xv

22 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. 1

23 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 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. 2

24 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. 3