Machining Performance Characteristics of Ti–6Al–4V Alloy Due to Ultrasonic Assisted Micro-EDM Using Rotating Tool Electrode

Titanium (Ti) alloys are extremely difficult-to-cut aerospace alloys due to their low thermal conductivity, high chemical reactivity, and high hardness. Making miniature holes in these alloys by traditional drilling is much difficult, because most of heat generated in the process passes through twist drill, which causes frequent failure of it. Electrical discharge machining (EDM) is an appropriate process for creating holes in these materials but it faces problem of debris flushing when hole size reaches to micro-range. All debris particles start to accumulate at bottom side, as hole progresses, which enhance arcing, short-circuiting, unusual discharges, etc. In account of all above mentioned problems, authors developed ultrasonic assisted micro-EDM (UA-MEDM) setup, in which tool is rotating and workpiece is vibrating. Further, the machining characteristics of Ti–6Al–4V have been investigated in the form of material removal rate (MRR), hole taper ( T a ), tool wear rate (TWR), and surface quality (SQ) of microholes due to variation of gap current, pulse off-time, pulse on-time, tool RPM, and ultrasonic power using one factor-at-a-time (OFAT) methodology on this developed setup. On the other hand machining characteristics have been studied when ultrasonic vibration and rotation of tool are switched-off. Surface quality of microholes and micro-tools has also been observed by using scanning electron microscopy (SEM). Experimental results show that rotating tool and vibrating workpiece give microholes of better quality with higher MRR.