Analysis of chip formation mechanism in machining of Al/SiCp metal matrix composites

Al/SiCp composites are known to cause a significant wear of cutting tools. But, with the use of PCD/CBN tools, machining can be continued over longer time duration. Nevertheless, the problem associated with the quality of machined surfaces such as pit marks and particle pull-out still persists. The quality of surface generated during machining can be easily related to the types of chips formed during machining of Al/SiCp composites as a function of processing conditions and composition of constituents in composites. It is observed from the Taguchi method-based experimentation using L27 (313) orthogonal array, that in machining of coarser reinforcement composites complete gross fracture takes place causing smaller segments of chips and higher shear plane angle. However, in finer reinforcement composites, secondary crack formation is evident at inner surfaces of the chips formed. Conceptual models illustrating these effects have been arrived at.