Assessment of machinability behaviour of LM24 – nano Al₂O₃ – gr hybrid composites through stir casting technique

Abstract This study is focused on developing a novel combination of a hybrid MMC made of LM24 aluminium alloy, nano Al₂O₃ and Graphite for enhanced machinability. The study conducts a series of experimental runs and evaluates surface roughness and material removal rate. The process parameters of spindle speed, feed, and depth of cut have been varied, while different weight percentages of nano Al₂O₃ (1%, 3%, and 5%) were incorporated into the LM24 metal matrix alloy along with 1 wt% of Gr. Response Surface Methodology (RSM) is used to optimize the turning parameters and enhance the machining performance for better quality and productivity. The derived optimal machining parameters have been verified through confirmatory tests. An analysis of variance (ANOVA) was used to determine the individual contributions of each parameter to the machinability characteristics. Surface morphology analysis revealed the uniform distribution of nanoparticle reinforcements in the metal matrix. The surface roughness and material removal rate of the machined nanocomposites were studied. The optimized outputs are a minimum surface roughness Ra 0.522 μm and maximum material removal rate MRR 110.2 mm³s^–1 The maximum hardness of the MMC composites has been 60.5 HRB.