Influence of Current Waveforms on Single Discharge Crater in EDM

Abstract

This paper describes the effects of the discharge-current waveform on the shape and removal volume of craters in electrical discharge machining (EDM). In EDM, it is known that removal efficiency, defined as the ratio of the removal volume to the volume molten by a single discharge, is no more than several percent. Hence, to increase the removal efficiency, the influence of the discharge current waveforms on the removal volume in a single discharge was investigated. Using cold tool steel plates and copper rods as the workpiece and tool electrode, respectively, the removal volume of workpiece with the polarity of positive was largest when a linearly increased and sharply turned off current was used with the pulse duration of 200μs.