Molecular dynamics study on the effect of discharge on adjacent craters on micro EDMed surface

Abstract Using molecular dynamics simulation (MDS), investigation was carried out to understand the mechanism of material removal during the formation of overlapping craters on surfaces obtained by micro electrical discharge machining (MEDM) and their effect on the crater surface. Apart from overlapping craters, two other cases were also considered viz. craters separated by a finite distance and craters coinciding at the periphery since these two will mostly occur during initial phase of machining. In all cases, the material removal was due to melting and vaporisation; it was also observed that the amount of material removal by vaporisation increased from 36% (approx.) in 1 st discharge to 44% (approx.) in the 2 nd discharge due to ease of vaporising the amorphous layer formed after the 1 st discharge. Moreover, final crater size viz. depth and diameter obtained in the 1 st crater measured at the end of MDS was relatively less as compared to 2 nd crater. The increase in crater depth and diameter increased with reduction in distance between discharges. The increase in diameter of 2 nd crater with respect to 1 st crater for all the three cases was observed both during MDS and on the actual surface generated by MEDM.