Graphite has high strength at high temperature, low coefficient of thermal expansion, good machinability and good thermal and electrical conductivity, so graphite electrode is widely used in metallurgy, electric furnace, EDM and other fields. In the field of EDM, the development of new graphite electrode materials and processing technology has expanded the application scope of EDM and improved its performance.
Compared with carbon electrode, graphite electrode has the advantages of low electrode consumption, high processing speed, good machinability, high machining accuracy, low thermal deformation, light weight, easy surface treatment, high temperature resistance, high processing temperature, electrode bonding and so on.
Although graphite is a very easy-to-cut material, graphite materials used as EDM electrodes must be strong enough to avoid damage during operation and EDM processing. The shape of the electrodes (thin wall, small rounded angle, sharp change) also requires higher grain size and strength of the graphite electrodes, which leads to the formation of graphite electrodes. During the processing, graphite parts are easy to crumble and the tools are easy to wear. Therefore, how to prevent the workpiece from crushing, improve the surface quality and reduce the cost of cutting tools has become an important issue in graphite electrode machining.
Conventional turning, milling and grinding methods are usually used to meet the needs of machining simple shape electrodes. However, the complexity of electrode geometry has been increasing in recent years. High-speed machining of graphite electrode has become a hot spot in EDM machining because of its high surface quality and high machining precision. Many manufacturers have introduced graphite high-speed machining centers. For example, Makino SNC64 CNC high speed graphite milling machine, R? The spindle speed is usually 10000–60000r/min, the feed speed is above 60m/min, the wall thickness is less than 1mm, and the minimum radius is less than 0.2mm.
As EDM graphite electrode high-speed machining is still a new process, the processing properties of different graphite materials are also different, for the graphite electrode high-speed machining of workpiece crushing, tool wear, processing strategies and other issues, rarely mentioned in the domestic literature. This paper introduces the research results of high performance graphite anode plate materials in Japan and Germany, including the cutting mechanism, cutting temperature, tool wear, chip treatment and other basic theories of graphite electrode materials, as well as the high speed machining strategy of graphite electrode and the selection of processing parameters.