Electrical discharge machining (EDM) is the result of electrical spark corrosion during pulse discharge between electrodes. The main reason of electric spark corrosion is that a large amount of heat is generated in the spark channel during the spark discharge, which is hot enough to make the metal on the electrode surface partially melt or even vaporize and evaporate to be removed.
Graphite is widely used as electrode material in EDM because of its low price, good machinability and low wear loss. It is reported that about 75% of the electrode materials for EDM in the United States are made of artificial graphite.
The particle diameter of graphite material directly affects the surface roughness of workpiece in EDM. The smaller the particle diameter is, the lower the surface roughness of workpiece can be obtained. Graphite electrode is easier to process, and the processing speed is obviously faster than copper electrode. For example, if graphite is processed by milling process, its processing speed is 2-3 times higher than that of other metal processing blocks, and no additional manual processing is required, while the copper electrode needs manual grinding. Similarly, if the high-speed graphite machining center is used to make electrodes, the speed will be faster and the efficiency will be higher. The tool and graphite with suitable hardness can reduce the tool wear and copper electrode damage.