Graphite has high temperature strength, low thermal expansion coefficient, good mach inability and good heat and 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 material and its processing technology expands the application range of EDM and improves its performance. Compared with the graphite electrode and the copper electrode has the advantages of electrode consumption, fast processing speed, good machining performance, high processing precision, small thermal deformation, light weight, high temperature resistance, easy processing, surface processing of high temperature, electrode bonding etc.. Although graphite is a very easy cutting material, but because the graphite materials used for EDM electrode must have sufficient strength to avoid damage during operation and EDM process, at the same time, electrode shape (thin, rounded, sharp change) and also put forward higher requirements on the graphite electrode and the grain size and strength, which leads to in the process of graphite work piece easily broken, the tool is easy to wear. So how to prevent the work piece from crushing, improve the surface processing quality and reduce the cost of processing tools become an important problem of graphite electrode processing. Conventional turning, milling and grinding methods can meet the demand of machining simple shape electrodes, but the requirement of electrode geometry complexity has been increasing in recent years. High speed machining high surface quality and high processing precision make graphite electrode high speed machining has become a hot spot in mold EDM processing,
Finishing should make the processing stable, have smaller shape error and good surface quality, at the same time the tool wear is small. Tool wear and machining costs are major considerations. In finishing machining, the influence of milling direction on machining precision and surface quality should be taken into account. In the feed milling along the surface will appear pull milling (upward knife) or drilling and milling (down knife) phenomenon, tool deformation will lead to work piece contour deviation. The contour deviation of drilling and milling is less than that of drawing and milling, and the contour deviation of reverse milling is better than that of forward milling. Therefore, considering the critical condition of tool quality and the stability and reliability of machining process, the best method of milling along the contour should be the combination of reverse milling and plane contour milling. In addition, when the milling, the envelope contour milling tool life is greater than drilling milling, reverse milling when the two almost.
