Study of electrical discharge machining parameters for mould steel AISI P20

This research paper aims to study the effect of parameters in Electrical Discharge Machining (EDM) process of mould steel AISI P20 when adjusted the parameter’s on-time, off-time, polarity electrode, and discharge current. The effects on the processing will be measured by investigating the Material Removal Rate (MRR), the Electrode Wear Ratio (EWR) and the surface quality from arithmetical mean roughness (Ra). The material used in the experiment is copper electrode on EDM of AISI P20 steel products. From the experiment it is found that the on-time and discharge current are affected to material removal rate, electrode wear ratio and the arithmetical mean roughness. When off-time decrease, material removal rate will be stimulated to increase but the off-time has only little effect to EWR and Ra.With regard to the polarity electrode, it is found that positive polarity electrodehas higher MRR and lower EWR than the negative polarity electrode, while the negative polarity electrode has better effect on surface quality than the positive when measured by Ra but there will be micro-cracking on the surface. The experiment shows that the best processing capability is at 100 μs on-time, 2 μs off-time, 14 A discharge current and positive polarity electrode, in which the MRR in experiment was 15.63 mm3/min and the EWR is 0.52 percent.