Electrical Discharge Machining Phenomena of Insulating Sialon Ceramics with an Assisting Electrode

In this paper, a new EDM method of insulating ceramics with an assisting electrode by a sinking electrical discharge machine and the estimated machining characterization are described.In this method, the electrical discharges occur in working oil on the interface between attached electrical conductive material which acts as assisting electrode and sialon insulating ceramics surface.The assisting electrode makes the workpiece surface electrically conductive at the beginning of machining.As kerosene is used as working fluid through this EDM process, the electrical conductive layer which is observed on the machined surface is considered as cracked carbon from working oil.Even after the assisting electrode is machined, the electrical discharge occurs in the gap region between the tool ekctrode and the insulating ceramics because an electrical conductive layer is generated on insulator surface by discharging.Therefore discharges continue during the EDM process.A mesh as an assisting electrode improve the machining rate and surface roughness much better than that with metal plate.In this paper the authors discuss by showing an EDMed example that the proposed method is available for machining a complex shape on sialon insulating ceramics.