EFFECT OF DIFFERENT TYPES OF ELECTRODES ON SURFACE RESIDUAL STRESSES INDUCED BY EDM PROCESS FOR AISI D2 DIE STEEL

Electrical-discharge machining (EDM) technique has been increasingly adapted to new industrial applications within the field of aerospace, medical, die and mould production, precision tooling, etc. This paper concerns with studying the effect of EDM input parameters (type of electrode, peak current, and pulse-on time) on the surface residual stresses. Response surface methodology (RSM) has been used to plan the experiments. The experimental plan adopts the two level full factorial design (FFD). To verify the experimental results, the analysis of variance (ANOVA) was used and regression models are built to predict the EDM output performance characteristics, including the surface residual stresses for AISI D2 die steel in terms of an empirical equations. The results obtained when using the copper and graphite electrodes showed that the minimum tensile surface residual stresses reaches with pulse current (22 A) and pulse on duration (120 µs). The results concluded that the using of copper electrodes induced tensile residual stresses about (13.3%) lower than when using graphite electrodes