Die-sinking EDM of Al6061-T6: interactions between process parameters, process performance, and surface characteristics

Abstract

Die-sinking electrical discharge machining (EDM) is the principal method used to machine critical components made of Al6061 alloy for space applications. Geometrical precision and surface roughness are among the most important acceptance criteria for these machined parts. The purpose of this research work is to identify the most significant parameters affecting the material removal rate (MRR), the electrode radius wear rate (EWR), and the surface roughness (Sa) when machining Al6061-T6 aluminum alloy by die-sinking electrical discharge machining and to use this knowledge in future work to generate accurate predictive models. To this end, ten universal machining parameters were selected, and using a Plackett–Burman Design of Experiments (DOE) approach, their influence and relative impact on MRR, EWR, and Sa were calculated and validated using experiments. A comprehensive Analysis of Variance (ANOVA) was then conducted based on the obtained results. It was found that the discharge current, the discharge duration, and the system voltage significantly affect the MRR, while these same three parameters plus the delay between two series of discharges significantly affect the EWR. The surface roughness was affected by the discharge current, the discharge duration, the voltage, the delay between two discharges, and the delay between two series of discharges. The obtained results were analyzed in terms of the relationship between energy input during machining and the surface modification of the material.