High Performance in EDM Machining of AISI D2 Hardened Steel Faizul Ezmat Abdul Hamid 1, a , Mohd Amri Lajis 2,b 1,2 Department of Mechanical and Manufacturing Engineering, Universiti Tun Hussein Onn Malaysia, 86400 Parit Raja, Batu Pahat, Johor Darul Takzim, Malaysia a hd100029@uthm.edu.my, b amri@uthm.edu.my Keywords: Electrical discharge machining; Powder metallurgy; High performance; Material removal rate; Tool wear rate Abstract. In this paper an attempt has been made to investigate the performance of an electrode made through powder metallurgy (PM) of copper tungsten during electrical discharge machining (EDM). Experimental results are presented on electrical discharge machining of AISI D2 hardened steel in kerosene with a copper tungsten (Cu35% - W65%) tool electrode made through PM method with a constant duty factor of 80%. In term of high performance EDM process, higher peak current (>20A) and pulse duration (>400µs) with a high machining efficiency were used. Experimental results have shown that machining at a peak current of 40A and pulse duration of 400µs yields the highest material removal rate (MRR) whereas machining at a peak current of 20A and pulse duration of 400µs yields the lowest tool wear rate (TWR). The lowest surface roughness appears at the lowest material removal rate which is at a peak current of 20A and pulse duration of 600µs. The optimum machining performance can be performed by the combination of pulse duration and peak current at 600µs and 40A respectively. Introduction Electrical discharges machining (EDM) has been extensively used in mould and die industries. Classified as a one of thermal advanced machining process, EDM is able to machine hard material such as metal alloyed and hardened steels. Its unique feature of using thermal energy to machine electrically conductive parts regardless of hardness has been its distinctive advantage in the manufacture of mould, die, automotive, aerospace and surgical components. Material removal rate (MRR) is an important performance measure and several researchers explored several ways to improve it. Most research has been studied on the effect of changes of machining conditions and parameters but there were very few studies on the improvement of machining speed by implementing the higher current intensity and pulse duration and at the same time try to maintain the good quality of surface integrity and reduced tool wear in EDM operation. High speed EDM is really desired by any metal fabrication industries which is very profitable by reducing lead-time of production. Earlier investigation showed that the combination of high electrical and thermal conductivity, high melting point and high wear resistance of EDM tool electrode is a basic requirement for high machining performance [1]. The basic requirement is vital to machine high hardness material i.e. hardened steel, titanium, tungsten carbide and inconel for prolonged machining. However, most single element tool electrode i.e. copper, graphite and brass are not fully satisfies the basic requirement. Therefore, research is going on to develop a composite material which satisfies the basic requirement of tool properties. Powder Metallurgy (PM) is a continually and rapidly evolving technology embracing most metallic and alloy materials, and a wide variety of shape. It is highly developed method of manufacturing reliable ferrous and nonferrous products [2]. The growth of PM industry during the last few decades is largely attributable to the cost savings associated net shape processing compared to other metalworking methods, such as casting or forging. EDM tool electrode can also be produced with desirable properties by the result of a combination of different materials. Advanced Materials Research Vol. 500 (2012) pp 259-265 Online available since 2012/Apr/12 at www.scientific.net © (2012) Trans Tech Publications, Switzerland doi:10.4028/www.scientific.net/AMR.500.259 All rights reserved. No part of contents of this paper may be reproduced or transmitted in any form or by any means without the written permission of TTP, www.ttp.net. (ID: 202.184.236.2-25/04/12,04:02:26)