Effect of Machining Parameters in Electrical Discharge Machining of D2 Tool Steel

Electrical discharge machining (EDM) is one of the important non-traditional machining processes and it is widely accepted as a standard machining process in the manufacture of forming tools to produce molds and dies. Since its introduction to manufacturing industry in late 1940s, EDM became a well-known machining method. The method is based on removing material from a work piece by means of a series of repeated electrical discharges, produced by electric pulse generators at short intervals, between an electrode (tool) and a part being machined in dielectric fluid medium. Copper electrodes with diameter of 9.5, 12 and 20 mm were used in electrode discharge machining of AISI D2 tool steel at two current setting of 3.5 and 6.5 A with the objective of determining possible correlation between the EDM parameter and the machinability factors. Each machining test was performed for 20 min and kerosene was used as the dielectric fluid. The material removal rate of the work piece material and wear rate of the electrode material were obtained based on the calculation of the percentage of mass loss per machining time. It was found that the material removal rate as well as the electrode wear rate was not only dependent on the diameter of the electrode, but also had close relation with the supply of current. Low current was found suitable for small diameter electrode, while high current for big diameter electrode.