Discharge Machining of Insulating Si_3N_4 Ceramics with added Al_2O_3 - Comparison with Sinking and Wire EDM

摘要

Insulating ceramic materials can be machined by electrical discharge machining (EDM) using the assisting electrode method with a sinking or wire EDM machine and electrically conductive material. In this machining process, electrically conductive carbon and carbide products adhere to the surface of the workpiece during discharge. The characteristics of the layer are affected by the electrical machining conditions and the physical characteristics of the workpiece. Typically, the machining conditions for SEDM and WEDM are very different. In this paper, to investigate the difference in the machining properties of SEDM and WEM, several experiments were carried out by varying the amount of Al_2O_3 added to the Si_3N_4 ceramics, and the size of the tool electrode. The material removal rate and the surface roughness were estimated for workpieces following EDM. Discharge waveforms were observed with a digital oscilloscope and analyzed by using the designed program. Machining properties were analyzed by considering the structure of the workpiece and the electrode diameter.