A thermo-electric model of material removal during electric discharge machining

Abstract

In Electro Discharge Machining (EDM), melting is the main process for metal removal. However, for short pulses (discharge duration <5 μs), melting does not account for the results as shown by the experiments reported. For short pulses, metal does not get enough time to get adequately heated and almost no melting takes place. The electrostatic force acting on the surface is a very important factor in the removal of metal for short pulses. For long pulses (discharge duration> 100 μs), this electrostatic force becomes very small and does not play a significant role in the removal of metal. In the model proposed, the electrostatic force acting on the metal surface and the stress distribution inside the metal due to this electrostatic force have been estimated. The variation of the yield strength with depth inside the metal has also been found out and finally the 'crater depth' due to this electrostatic force has been calculated.