EDM of Insulating Ceramics by Electrical Conductive Surface Layer Control

Electrical discharge machining (EDM) is available and effective for precise, complex shaping. Recently, by using the assisting electrode method, EDM can be applied to insulating ceramics. In this method, a pulse discharge that is longer than the set pulse duration is generated. With this long pulse discharge, an electrical conductive layer is formed on the surface of the insulating ceramic, which maintains stable machining. In this paper, we describe how to control this electrical conductive surface layer. The layer control sequence is applied to the wire electrical discharge milling method (WED-milling) with a wire guide on a hemisphere tip in order to realize 3D machining of insulating ceramics.