Graphite Electrode For EDM
Graphite is the preferred electrode material for EDM due to its ability to provide superior performance. It is easy to machine and can withstand high temperatures without burning, chemically changing or melting. It can also be redressed numerous times, making it a cost effective choice compared to copper. However, the quality of the graphite used is the key to maximizing machining performance.
There are a variety of grades available and selecting the proper one for your application will ensure you can achieve optimum EDM results. Less critical applications with open tolerance or minimal electrode details could utilize a graphite grade that has large particles, lower strength and a more economical price. Alternatively, highly detailed applications with critical features and extreme tolerance requirements would require a premium graphite grade with smaller particle size and tighter pore structure for the highest possible machinability and optimum performance.
For example, if your application requires the machining of fine, intricate details, thin ribs or thin cross sections, you should select an ultrafine graphite grade. These grades are able to handle the highest current intensity and can trim hours from your process time. They have a uniform microstructure to allow aggressive settings, and they wear slower than copper or copper-tungsten, so you can increase your cutting speed for quicker machining.
Despite its low density, graphite has excellent conductivity allowing efficient metal removal. It also has a much higher melting point than copper, so it can maintain its form during the spark process and will not burn or change shape. This provides a better surface finish and reduces corner erosion.
