I、 Graphite is selected as the electrode material, and more than 90% of the electrode materials in Europe are graphite. Copper, once the dominant electrode material, has almost lost its advantages compared with graphite electrode.
II、 Reasons for graphite as electrode:
1. Faster processing speed: generally, the machining speed of graphite can be 2 ~ 5 times faster than that of copper; The speed of EDM is 2 ~ 3 times faster than that of copper;
2. 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, which is easy to deform due to heating; The sublimation temperature of graphite is 3650 ℃; The coefficient of thermal expansion is only 1 / 30 of that of copper.
3. Lighter 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); It is more suitable for the application in large molds.
4. Lower discharge consumption; Because the spark oil also contains C atoms, during EDM, the high temperature causes the C atoms in the spark oil to be decomposed, and a protective film is formed on the surface of the graphite electrode to compensate the loss of the graphite electrode.