Discharge Machining of Insulating Si3N4 Ceramics with added Al2O3

Abstract

Several insulating ceramic materials, including natural diamond, have been machined by electrical discharge machining ( EDM) using the assisting electrode method that has been proposed by the authors' group. The machining properties were affected by the electrical machining conditions and by the physical characteristics of the workpiece. In this paper, to investigate the dependence of the machining properties on amounts of additives, three types of insulating Si3N4 ceramics were machined by sinking EDM and by wire EDM. The material removal rate and the surface roughness were estimated on the EDMed workpiece, and the discharge waveforms were analyzed using the digital oscilloscope. Different dependences on the amounts of added Al2O3 were observed for S-EDM and W- EDM. The machining property of the material removal rate depended on the size of the electrode area for each EDM method.