Effects of gas-assisted perforated electrode with rotation on the machining efficiency of PMEDM of titanium

Abstract

Bioactive hydroxyapatite (HA) powder has been used as an addition in dielectrics for powder-mixed electrical discharge machined titanium (Ti) alloys as orthopedic implants. However, the low electrical conductivity of the HA powder renders discharge unstable and results in a low machining efficiency. This study aimed to improve the material removal rate (MRR) of electrical discharge machining using gas-assisted perforated electrodes and electrode rotation. The effects of gas flow rate and electrode rotational speed on the MRR, electrode wear rate (EWR), and surface roughness were investigated. The MRR increased significantly when an appropriate gas flow rate (0.05 L/min) was used, thus enhancing the removal of debris absorbed on bubbles during the retraction of the tool electrode. However, a lower (0.02 L/min) or higher (0.1 L/min) gas flow rate caused a decreased MRR. An increased electrode rotational speed increased the MRR and reduced the surface roughness of Ti. Nevertheless, the combination of gas assistance and electrode rotation cannot further improve the MRR. Instead, it increased the EWR.