Experimental and statistical investigation into surface characteristics in micro milling of bottom pouring/gravity stir cast Al6061 alloy

Micro milling offers the best way to create micro channels; however, the burr formation and surface roughness of the micro channel are difficult to control. Micro channel fabrication and their characterization of stir cast Al6061 are rarely investigated. In the present study, Al6061 alloy was processed by the bottom pouring stir casting method. The micro channels were fabricated on a base and stir cast Al6061 alloys using TiSIN-coated micro end mill tools. The influence of micromachining parameters such as spindle speed, feed rate, and depth of cut on burr formation, cutting force, burr size, and surface roughness was investigated. A comparison was made between the findings obtained from the micro milling of the base and stir cast Al6061 alloys. The surface morphology of fabricated micro channels was analysed and correlated with the roughness profile to understand the channel profile and burr formation. The top burr formation mechanism in stir cast Al6061 alloy was investigated in detail. Low feed rate, low depth of cut, and high spindle speed produced the micro channel with fewer burrs, low surface roughness, and low cutting forces. At the optimum parameter, stir cast Al6061 alloy showed an approximate 420%, 16%, and 300% increase in Fy, Fz, and Ra, respectively, as compared to the base Al6061 alloy. Adhesion wear, built-up edge, and microchipping were found to be the main tool wear mechanisms in micro machining of stir cast alloy. This study directs the choice of cutting parameters for the stir cast micro milling process.