EDMis immensely used in the modern era of industries to machine the materials that are hard to machine by conventional machining methods. Present paper deals with machining of H-13 tool steel with different types of electrodes in the EDM. A set of input parameters were chosen at different levels and their effect has been studied on material removal rate of the work piece. Experimentation showed that Polarity, Duty Cycle & Retract Distance are the most significant factors under the chosen

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... ons of machining Keywords EDM, Material Removal Rate (MRR), Surface Roughness (SR), Powder Metallurgical Compact different Electrodes INTRODUCTION Electrical Discharge Machining is one of the most preferred non-traditional machining processes used to machine hard to machine, complicated designs of electrically conductive materials. It is a thermal process that involves melting and vaporization of the pair of work piece and electrode. Studieshasshownthat combined pulse generation and a relaxation circuit enhances the tool electrode transfer [1].EDM with pulsing relaxation generator using a powder compact electrode and reverse polarity setting can modify the surface properties of a machined surface [2]. A new method named electrical discharge alloying is used for modification of surface of aluminium [3]. PM electrodes affect the micro-and macro variables in EDM and the properties of PM electrodes can be controlled over a wide range by adjusting the compacting and sintering conditions [4]. In some cases compounds of ZrB2 and TiSi with Cu at a variety of compositions, for EDM electrodes with either solid-state sintering or molten state sintering are also used [5].Rapid Prototyped-sintered EDM electrodes show good performance in finishing the surface and best results can be obtained by addition of 15% TiC, i.e. the lowest tool wear rate, highest material removal rate and best surface finish [6]. Besides erosion of work material during machining, the essential nature of the process consequences in removal of some tool material also. This can be reduced to some extent under precise machining conditions by using either composite electrodes or by dispersing metallic powders in the dielectric or both [7]. Experimentation shows that on machining AISID2 tool steel in kerosene; it is observed that copper tungsten Powder metallurgical electrode gives improved multi-objective performance than ordinary Cu electrode [8].