Optimization process parameters for In-Situ Metal Matrix Composites AA6061-ALN

AA6061–AlN metal matrix composites were fabricated by stir casting with 0, 2.5, 5, and 7.5 wt.% AlN, then drilled under controlled spindle speed (600–2400 rpm), feed (0.05–0.20 mm/rev), point angle (100–130°), and drill diameter (6–12 mm) to quantify machinability. Surface roughness, thrust force, and chip morphology were measured. Surface roughness increased with both point angle and AlN content, from 2.23 μm at 0% AlN100° to 3.70 μm at 7.5% 130°. For the unreinforced alloy, thrust force dropped from 175 to 125 as speed rose from 430 to 2200 rpm, indicating improved cutting stability at higher speeds. Reinforcement altered chip formation toward larger, segmented chips. Overall, lower point angles (100–110°), smaller drills (6–8 mm), modest feeds (≤0.10 mm/rev), and higher spindle speeds (≥1800 rpm) favored lower roughness and thrust. The results provide practical guidance for parameter selection to balance hole quality and productivity when machining AA6061–AlN components for transportation and aerospace applications.