Die-Sink electrical discharge machining behaviour of AZ31 alloy and AZ31/ES + WS ₂ surface composite

Using friction stir process technique, egg shell and WS2 particles were reinforced in AZ31Mg alloy. Initially, the mixer of 80% egg shell particles and 20% WS2 particles was encapsulated in the drilled cylindrical holes of AZ31 alloy plates, then friction stir process was performed using a taper threaded pin FSP tool at tool rotational speed of 1000 rpm, axial force of 6 kN, 2° tool tilt and transverse rate of 10 mm/min. After that, electrical discharge machining process was performed on AZ31 base material and AZ31/ES + WS2 composite using a copper alloy electrode tool. The EDM process elements of gap voltage, pulse current and pulse duration were opted at three levels and 27 experiments were performed based on L27 orthogonal array. The output response characteristics like tool electrode wear rate, material removal rate and surface roughness of AZ31 base material and AZ31/ES + WS2 composite were observed and explored. The TOPSIS optimisation technique was applied and the optimal EDM process elements of 50 V gap voltage, 15 amp pulse current and pulse on duration of 30 µs with MRR of 0.2996 g/min, TWR of 0.0032 g/min and SR of 14.61 µm were reached for AZ31 base material. The optimal EDM process elements of 50 V gap voltage, 10 amp pulse current and 30 µs pulse on duration with MRR of 0.1603 g/min, TWR of 0.0018 g/min and SR of 11.69 µm were reached for AZ31/80wt.%ES + 20wt.%WS2 hybrid surface composite. The SEM and EDX based surface morphological study was carried out on optimally EDM processed AZ31 base alloy and FSPed AZ31/ES + WS2 surface composite.