絶縁性 Sialon セラミックスの放電加工特性に及ぼす補助電極材料の影響

抄録

In this paper, a new EDM of insulating ceramics with an assisting electrode and its machining characteristics are described. In this method, a metal plate or several metal mesh sheets is attached on the surface of sialon ceramics as an assisting electrode. The machining starts on the assisting electrode down to the insulating ceramics with kerosene as working fluid. The ceramics surf ace was covered with a black layer which consists of α-SiC and C, and this layer keeps electrical conductivity on the ceramics surface during the machining. When the tool electrode reaches at the boundary between the metal plate and the ceramics, the machining does not proceed for several minutes while the black layer forms on the ceramics surface. This period is named as transition time. The transition time and amount of adhesive black layer depend on the physical properties of assisting electrode such as melting point and thermal conductivity. Laminated several sheets of metal mesh as the assisting electrode improve machining rate and surface roughness much better than that with metal plate. The proposed method is available for machining a complex shape on sialon insulating ceramics.