Surface finish and tool wear in drilling Al-SiC metal matrix composites fabricated by hot isostatic pressing

Particle-reinforced metal matrix composites (MMCs) are emerging as essential engineering materials for advanced applications, not only in the aerospace sector but also in the automotive industry. These composites are produced by combining a metal matrix with reinforcement materials such as ceramics, fibers, or particles to enhance mechanical properties, including hardness, quality, and wear resistance. Despite their advantages, the machining of MMCs presents significant challenges due to the presence of hard reinforcements, which can increase tool wear and cutting forces, thereby degrading machinability. Furthermore, variations in the weight percentage and size of the reinforcing particles influence both the morphological and machining behaviours of the composites. This thesis investigates the surface finish and tool wear during the drilling of Al-SiC MMCs fabricated via hot isostatic pressing. Drilling tests were conducted on two composites, both with an Al-6061 alloy matrix but differing in SiC particle weight percentages and sizes. The experiments employed a fixed feed rate, cutting speed, and a five-steps drill with a consistent depth of cut, repeated across nine holes. Periodically the DLC-coated tools wear was measured, and the inner surfaces of the drilled holes were examined to detect potential defects.