Electric Discharge Machining of Titanium Alloy under Cu Mixed Dielectric Medium

In the current research work, an attempt has been made to machine Ti6Al4V using Powder Mixed Electric Discharge Machining (PMEDM) technique. The experiments were designed utilizing central composite response surface methodology by varying current, pulse on time, gap distance, and powder concentration at five different levels, whereas Material Removal Rate (MRR), Tool Wear Rate (TWR), and Surface Roughness (Ra) were documented as responses. The MRR reduced with an increase in powder concentration until the concentration reached 7.5g/l because incorporated particles observed the major proportion of heat, and at 10g/l, MRR increased due to the bridging effect. The TWR and Ra reduced with an escalation in powder concentration due to expansion in the spark gap, facilitating the flushing of machined debris. The surface topography revealed cracks, pits, globules, and craters. Moreover, with the addition of particles, surface quality improved owing to the elimination of re-melted layers. The parameters were optimized using the Grey Relational Analysis (GRA), and the combination of 2.5g/l powder concentration, 20A current, 50µs ton, and 4mm gap distance offers the best machining performance.