Experimental determination of appropriate tool material for machining different work materials by EDM process

Abstract

'I11e present work deals mainly with the machining of conductive work materials by direct application of electric sparks. Electro spark apparatus is made of a circuit including both the work piece and the tool as electrode, continuously spaced apart and mutually insulated from each other except during a high frequency sequence of separate time spaced unidirectional spark discharge caused to take place between them. Electrical discharge machining was performed on materials copper, brass, stainlesssteel, mild-steel and cast-iron, using the same type of materials a~ electrodes ..The etlect of process pramaters and variation of time on material removal rate (MRR), surface roughness(SR), recast layer (RCL), tool wear, accuracy of machining and surface finish were studied. It was observed that though material removal rate increases almost linearly during in the machining process, surface fmish decreases due to re solidification of micro chip on the surface to form a recast layer. No crack was found in the r(:cast layer in the case of brass and copper electrodes and softened heat affected zone was observed below the recast layer. Machining time as well as power control the material removal rate (MRR), accuracy of machining, and the depth of the recast lay;":, but current plays the dominating role on surface finish in the E.D.M process.