Graphite mold has the advantages of high machining precision and good surface effect, especially in precision, complex, thin-walled, high hard material mold cavity processing. Compared with copper, graphite die material has the advantages of low consumption, fast discharge speed, light weight and low thermal expansion coefficient, so it gradually becomes the mainstream of EDM material instead of copper electrode. In contrast, graphite electrode materials have the following six advantages：
1. It's fast. Graphite discharge is 2-3 times faster than copper, and the material is not easy to deform. It has obvious advantages in the processing of thin rib electrode. The softening point of copper is about 1000 degrees, and it is easy to deform due to heating. The sublimation temperature of graphite is about 3650 degrees. In contrast, the thermal expansion coefficient of graphite mold material is only 1 / 30 of that of copper;
2. Low loss. Because there is C atom in the spark oil, the C atom in the spark oil is decomposed at high temperature during EDM, and a protective film is formed on the surface of the graphite electrode to compensate the loss of the graphite electrode;
3. Easy to polish. As the cutting resistance of graphite is only 1 / 5 of that of copper, it is easier to grind and polish by hand;
4. No burr. The burr of copper electrode needs to be removed by hand after processing, while graphite electrode has no burr after processing, which not only saves a lot of cost and manpower, but also makes it easier to realize automatic production;
5. Light weight. The density of graphite is only 1 / 5 of that of copper. When large electrode is used for EDM, it can effectively reduce the burden of machine tool (EDM), and is more suitable for the application of large mold;
6. Low cost. Due to the rising price of copper in recent years, the price of graphite is lower than that of copper; For the universality of Toyo carbon in the same volume, the price of graphite mold products is 30% to 60% lower than that of copper. The price is relatively stable, and the short-term price fluctuation is relatively small.