Optimizing drilling conditions for AZ61A magnesium alloy

For magnesium alloys, optimizing the machining conditions is necessary to prevent ignition of chips. In this study, effects of point angles of drill bits and drilling parameters on surface roughness and cutting resistance forces were measured and studied. Surface roughness and cutting resistance forces are increased following the increase of point angle and material removal rate. Point angle (2p) descends from 118° to 55° producing the smoothest machined surface and minimum variance in the measured roughness. In addition, effect of drilling operation on varying microstructure of AZ61A was also investigated in this study. The drilled sample showed a minimum extent of deformation twinning layer, when the drill bit adopted a point angle of 55°. The drilled sample developed a superior surface roughness and a short extent of twinning layer generated on the matrix of machined sample, if a 5%NaOH solution was used as lubricant and a 55° point angle was used.