MRR and surface morphological analysis of electrical-discharge-machined Co–Cr alloy

Electrical discharge machining (EDM) confirmed its importance in the machining of hard and complex geometrical material which are difficult to machine or modified by traditional machining technique. The EDM process parameters – namely, pulse-on time, pulse-off time, current, voltage and dielectric medium – significantly influence the machining performance, such as surface traits, roughness and surface films. Therefore, in this study, the influence of EDM performance parameters on the metal removal rate (MRR) and surface roughness (SR) was examined. Experimentation was conducted according to the Taguchi L18 orthogonal array. Further, the analysis of variance (ANOVA) was employed for analyzing the S/N ratio results of the MRR and SR of various samples. The results revealed that cobalt (Co)–chromium (Cr) alloy substrates machined with a tungsten (W)–copper (Cu) electrode at the higher current setting (16 A, P _on = 150 μs, P _off = 150 μs) in EDM oil exhibited appropriate MRR and surface roughness value. Moreover, the EDM surfaces also exhibited suitable biocompatibility and excellent osseointegration.