Machining characteristics of ZrO{sub}2 ceramics by electrical discharge machining -effect of graphite electrode-

摘要

Before this report we have shown that EDM of insulating ceramics is possible with an assisting electrode method. The process of assisting electrode method is that a carbonization layer is formed on the ceramics surface by cracked carbon fromworking oil and this layer keeps electrical conductivity on the ceramics surface during the machining. When ZrO{sub}2 ceramics was machined with a copper tool electrode, enough carbonization layer was not formed on the machined surface from crackedcarbon, and then machined surface was rough. In this paper, graphite is used as a tool electrode to let promote carbonization reaction. As a result, carbonization reaction is promoted and the enough carbonization layer forms on the machined surface. Thesurface roughness are much improved comparing with the machined surface by use of copper electrode.