Experimental Investigation of Surface Integrity and Multi-Objective Optimization of End Milling for Hybrid Al7075 Matrix Composites

Cost effective machining of hybrid metal matrix composites (HMMC’s) with required surface integrity and without surface flaws is a challenging task for modern industries. This research explores the effect of end milling factors (spindle speed, feed rate, and depth of cut) and also weight percentage of reinforced materials on the surface integrity (surface roughness and microhardness) and material removal rate during machining of hybrid Al7075/SiC/Gr composites. Response surface methodology (RSM) is selected for experimental design and experimental results are analyzed using analysis of variance (ANOVA). Further, multi-objective optimization is carried out using composite desirability function. In addition, the morphology of the milled surfaces is examined for defining the flaws that affect quality of the milled surfaces. The experimental results reveal that apart from spindle speed and feed rate, the weight percentage of reinforced materials significantly affects the surface integrity of hybrid Al7075/SiC/Gr composites. The obtained optimum levels of the factors are spindle speed at 1000 rpm, feed rate at 0.0677 mm/rev, depth of cut at 1.1869 mm, and weight percentage of reinforced materials at 12.6970% that produce optimal values of the considered responses i.e. material removal rate up to 2043 mm 3 /min, roughness up to 1.29 μm and microhardness up to 142.36 μH.