Analytical modeling of subsurface damage depth in machining of SiCp/Al composites

SiC particle reinforced aluminum matrix (SiCp/Al) composite has been one of the key light metal matrix composites, which is widely used in aerospace and electronics industries due to its excellent material properties. However, the abrasive particles within the materials easily lead to severe tool wear during machining, and the subsequent machining-induced subsurface damage (SSD) will significantly affect the fatigue properties of composite structures. In this paper, an analytical model considering the effects of reinforced particle, thermal-mechanical coupling, and tool wear is first proposed to predict the SSD depth during cutting of SiCp/Al composites. The two-body abrasion and three-body rolling mechanisms are introduced to describe the effects of the particles on the tool-chip interface friction. The mechanical stress and thermal stress induced by mechanical load and thermal load, respectively are simultaneously taken into account. Meanwhile, the tool wear is considered in modeling of friction characteristic of tool flank-workpiece. The SSD depth is evaluated as a measure of variation in microhardness along the depth normal to the cross-section of the machined surface. The correctness of the proposed model was validated by the orthogonal cutting experiments of SiCp/Al composites under different tool wear values and feed rates. A good agreement is found by comparing the predicted and experimental results, which proves that the proposed model can accurately predict the SSD depth with an error of 7.8% in average. Furthermore, the results indicate that even a new tool is used, the SSD depth can reach to hundred micros level during machining of SiCp/Al composites, which is significantly greater than homogeneous metal machining.