In Europe, over 90% electrode material is graphite. Once a traditional electrode material with dominant status, the advantage of copper have almost disappeared when comparing with graphite. As spark oil also contains C atom, during dominant position, high temperature results to resolve C atom of spark oil, then becomes protective film on the surface of EDM graphite electrode, which compensates the consumption of graphite electrode.
Advantage of EDM graphite:
1. Faster processing speed. In the normal condition, the speed of graphite mechanical processing is 2-5 times faster than copper and speed of discharging is 3-5 times faster than copper.
2. Material is not easier to deformation. Its advantage is more obvious in the process of thin steel material. Softening point of copper is 1000 degree, which is easy to deformation if suffered by heat. Sublimation temperature of graphite is 3650 degree. Its coefficient of thermal expansion is only one thirty of copper.
3. Lighter weight. The density of graphite is only one fifth of copper. Large graphite electrode could effectively reduce the burden of EDM tool during discharging process. It is more suitable for the application of mould.
4. Less dicharging consumption. As spark oil also contains C atom, during dominant position, high temperature results to resolve C atom of spark oil, then becomes protective film on the surface of EDM graphite electrode, which compensates the consumption of graphite electrode.
