Accretion Machining by EDM with Thin Electrode (1st Report)

Abstract

Accretion machining by electrical discharge machining (EDM) with a high wear rate of green compact or semisintered electrodes has recently been carried out. Also, it has been observed that the wear rate of thin electrodes for various materials is very high with a high discharge current. In this study, a thin tungsten electrode is used for material accretion or surface modification of a small area. For this purpose, continuous discharge and single discharge machining experiments were performed by EDM with a thin electrode. Then the voltage and current waveforms and the cross section of the accreted surface were observed. In accretion machining, these waveforms revealed a continuous short-circuit phenomenon and a wire explosion phenomenon subsequent to the continuous short-circuited state. These observations indicated that the accreted layer was very hard (1000HV) and that the accretion area was very small (150μm in diameter). This clearly indicates that microaccretion machining can be performed using this technique.