Mold in the home appliances, automotive, electrical, aerospace and other industrial areas has increasingly become the main process of industrial production, the main process equipment, and bear the 60%-90% of these industries in the production of parts and components of the processing. In recent years, high speed milling has broken through the limitation of traditional milling hard, high strength and high toughness die materials. But electric discharge machining with high machining accuracy and surface quality, wide processing range, especially in high speed milling can match in the advantage of joints, high hard materials of the mould cavity machining of complex and precise, thin-walled, narrow, so in electrical discharge machining (EDM) will still be the main means of the mold cavity processing. Because the graphite electrode (compared with copper) electrode consumption less, electrical discharge machining speed, good machining performance, light weight, heat expansion coefficient and other advantages, and gradually replace the copper electrode to become the mainstream of the EDM electrode. Compared with copper, graphite electrode has the advantages of less consumption, high discharge speed, light weight and small thermal expansion coefficient. Therefore, it is the main. In contrast, graphite electrode material has the following advantages:
1. Fast: Graphite discharge faster than copper 2-3 times, the material is not easy to deform, in the processing of thin reinforced electrode have obvious advantages, copper softening point in 1000, easily due to thermal deformation and graphite sublimation temperature is about 36.5 degrees, compared with, graphite material thermal expansion system only a few copper 1 / 30.
2 Light weight: the density of graphite is only copper 1/5, large electrode discharge machining, can effectively reduce the burden of machine tool (EDM), more suitable for large-scale mold application;
3 Little loss: because the spark oil contains C atoms, in the discharge machining, high temperature leads to the C atoms in the spark oil is broken down, and the surface of the graphite electrode to form a protective film, the loss of the graphite electrode;
4 No burr: copper electrode in the end of the process, it is necessary to manually remove the burr, and graphite processing without burr, which not only saves a lot of cost and manpower, but also easier to achieve automated production;
5 Easy polishing: because the cutting resistance of graphite copper is only 1/5, more easily by hand grinding and polishing operation;
6. Low cost: as a result of rising copper prices in recent years, now, the price of the isotropic graphite is lower than that of copper; under the same volume of graphite products price than copper low 30 to 60 percent, relatively stable prices, short-term price fluctuations relatively speaking, is relatively small.
