Multi-response optimisation of EDM of AISI D2 tool steel using response surface methodology

In this work, the response surface methodology (RSM) was used to investigate the influence of processing variables on two responses of electrical discharge machining (EDM) characteristics of AISI D2 steel. The response functions considered are material removal rate (MRR) and surface roughness (Ra), while machining variables are pulse current, pulse on time, duty cycle and gap voltage. The effects of the machining parameters were studied by adopting central composite design (CCD). The response variables were fitted to predictive quadratic polynomial models using multiple regressions, which reveal that pulse current is the most significant machining parameter on the response functions followed by pulse on time and gap voltage for MRR. However, the pulse current is most significant factor governing Ra. Applying the composite desirability function method, the optimal-setting of the parameters was obtained for MRR and Ra with reduced number of experiments that needed to provide sufficient information for statistically acceptable results.