Machining Characteristics of Wire Electrical Discharge Machining on Insulating Si 3 N 4 Ceramics: -Relationship between Electrical Conductive Layer and Machining Characteristics-

In recent years, ceramics materials have found increased use in industry. However, some of them are insulating ceramics that cannot be machined by conventional electrical discharge machining. In this study, we developed a special wire EDM machine for investigating the machining characteristics of insulating ceramics. The machining characteristics of Si3N4 insulating ceramics, especially surface roughness, are described. It was confirmed that long-pulse discharges are minimally generated under the second cutting conditions where small discharge craters are uniformly formed on the machined surface. The resulting surface roughness was improved down to 4μmRz. In addition, a unique process of machining with insulating ceramics, in which the threshold level becomes almost of the same as the voltage between the discharge and power supply positions, was observed.