Analysis of material removal rate and surface quality during rotating magnetic field-assisted EDM of AISI D2 tool steel

Abstract

A major concern of machining stability in electrical discharge machining (EDM) is the accumulation of debris in the gap. Therefore, removing debris from the gap quickly and effortlessly enhances the performance of EDM. In this investigation, Rotating Magnetic Field (RMF) has been integrated with the EDM to form RMF-assisted EDM (RMF-EDM). Later, this study compares the performance of RMF-EDM with the conventional EDM process while performing machining on AISI D2 tool steel. The study also focuses on the effect of RMF speed, magnetic field strength, and current on surface roughness (Ra), material removal rate (MRR), tool wear rate (TWR), and surface morphology. The results reveal that the RMF-EDM provides better performance compared to EDM with a stationary magnetic field assisted EDM (MF-EDM) and conventional EDM in terms of both MRR and surface quality. It has also been observed that the increase in rotating speed enhances MRR and TWR to reach a peak at 1000 rpm before declining at higher speeds under the magnetic field strengths of 0.3 T and 0.6 T. A concurrent trend is observed in surface quality; Ra initially improves as the speed approaches 1000 rpm but deteriorates significantly on further increases in the rotating speed. There is a trade-off in terms of magnetic field strength; the highest MRR and best surface finish are observed at 0.3 T, but the lowest TWR is achieved at 0.6 T. The RMF-EDM at 1000 rpm outperforms the conventional EDM, achieving improvements of 31% and 23.16% on average in MRR and Ra, respectively. In comparison to MF-EDM, RMF-EDM with 1000 rpm improves MRR and Ra by an average of 27.33% and 19.61%, respectively. Moreover, the field emission scanning electron microscopy (FESEM) images confirm the least presence of defects such as unflushed debris, resolidified material, pits, and cracks is found at an RMF speed of 1000 rpm. Lastly, analysis of variance reveals that RMF speed has a significant effect on MRR, TWR, and Ra, with a percentage of contribution of 22.14, 17.17, and 86.15, respectively.