Comparative study of copper and graphite electrodes performance in Electrical Discharge Machining (EDM) of die steel

Abstract

Electro discharge machine (EDM) is one of the unconventional machining process used to remove material difficult to machine. Its unique characteristic is to machine that type materials which are hard and electrically conductive materials using electro-thermal energy that is difficult to machine using traditional machining methods like turning and milling etc. Die-steel has a wide range of practical applications, including punching tools, mandrels, mechanical press forging die, mould manufactureand so on. In this work, high carbon high chromium die-steel used as workpiece, electrolytic copper and pure graphite are used as a tool. In addition, parametric analysis have been completed by conducting a set of experiment using kerosene oil as dielectric medium. Impact on the surface roughness (SR), Material Removal Rate (MRR), and white layer (WL) due to the discharge current or peak current (I or Ip), pulse on time (Ton), pulse off time (Toff), and voltage have been studied. The experimental results reveal higher MRR for copper and graphite for sample having the same input parameters. However, MRR, SR, and WL all decreases when the pulse on duration (Ton) is prolonged.