Comparison of machining performance of hole-sinking micro-EDM without and with ultrasonic vibration on titanium alloy

Abstract

Titanium alloys are highly demanding in aerospace industries due to its high strength-to-weight ratio and high hot hardness, and termed as difficult-to-machine materials. Creating microholes of high accuracy in these materials is challenging task for manufacturing industries. Conventional twist drills are generally failed in the micromachining of Titanium alloys due to the low thermal conductivity of these alloys. In consideration of all these problems, authors used self-developed hole-sinking micro-EDM (HS-MEDM) setup without and with the assistance of ultrasonic vibration (UV) to create microholes in Titanium alloy (Ti-6Al-4V) workpiece. Comparative study regarding machining performance in terms of material removal rate (MRR), tool wear rate (TWR), hole taper (Ta) and overcut (OC) at different gap current, pulse on-time and pulse off-time has been reported without and with assistance of UV. It was found that HS-MEDM with UV is more advantageous in producing microholes with higher MRR, lower TWR, Ta and OC, and smoother surface.