The research investigates the impact of process parameters on the Material Removal Rate (MRR), Tool Wear Rate (TWR), and surface roughness (Ra) of a Titanium alloy under Copper (Cu) mixed Electric Discharge Machining (PMEDM) using an Aluminium – 10%graphite (A2) composite tool material. Under optimal conditions of P_on=60 µs, P_off=8 µs, and current=7A, machining with an A2 composite tool achieved an MRR of 0.1 mm³/min, a TWR of 0.0016 mm³/min, and an Ra of 0.847 µm. The introduction of 5 g/l of Cu powder into the dielectric fluid minimized TWR to 0.00122 mm³/min, indicating that the powder effectively absorbed and dissipated heat, reducing tool wear. At 10 g/l, TWR peaked due to the bridging effect, where particles created a barrier between the tool and workpiece, increasing tool wear. Beyond 10 g/l, TWR decreased due to debris densification, where the particles compacted together, reducing their ability to absorb heat and protect the tool. Surface roughness with a minimum Ra of 2.69 µm achieved at 5 g/l, but worsening as the concentration increased, reaching a mean Ra of 6.29 µm at 25 g/l. Ra also increased with higher Pon values, peaking at 5.81 µm at 75 µs Pon, indicating that longer pulse-on times allowed more heat to accumulate, leading to greater surface irregularities. Higher currents led to increased Ra, indicating surface quality reduction due to the intense heat generated, which could cause melting and re-deposition of material on the surface. SEM analysis revealed distinct surface characteristics based on the concentration of Cu powder in the dielectric fluid. At higher concentrations (25 g/l), the surface exhibited deep pits, craters, and globules, indicating excessive heat generation and inadequate flushing of machined debris. Lower concentrations (10 g/l) showed reduced pit and crack sizes, with some carbon content deposition from the dielectric fluid. Further reduction to 5 g/l significantly improved surface quality, with minimal cracks and redeposited material.

Keywords: EDM , Optimization , Surface topography , Machining , Dielectric