Study of surface crack density and microhardness of Aluminium 6061 alloy machined by EDM with mixed powder and assisted magnetic field

Abstract

Magnetic field assisted powder mixed electrical discharge machining (MFAPM-EDM) has emerged as hybrid electrical discharge machining (EDM) technique which improves machining performance by the addition of powder in dielectric and under the influence of magnetic field. In the present article, Aluminium 6061 alloy was machined through fabricated MFAPM-EDM set-up considering the one-parameter-at-a-time method. The individual effect of process parameters, namely pulse on duration (P_ON), pulse off duration (P_OFF), discharge current (I_P), magnetic field strength (MF) and powder concentration (P_C) on surface crack density (SCD) and micro hardness (MH) has been studied. Pulse on duration was observed as the most dominating process parameter accompanied by peak current, powder concentration and magnetic field for both SCD and MH. Lower SCD (0. 0063 µm/µm ² ) and higher MH (188. 21 HV) on machined surface were observed at P_ON= 90 µsec, P_OFF=45 µsec, I_P=13 A, P_C =10 g/l and MF= 0. 3 T. Machining of AA6061 with MFAPM-EDM process revealed 85% and 76% improvement in SCD and MH, respectively. XRD analysis witness an increase in MH due to the presence of oxide as well as carbide layer on machined surface.