Enhanced machinability of SiCp/Al composites with laser-induced oxidation assisted milling

Abstract In this study, an innovative machining process called laser-induced oxidation assisted milling (LOM) is proposed. A polycrystalline diamond (PCD) cutting tool is applied to machine 55% SiCp/Al composites. The laser-induced oxidation mechanism is investigated. Under the condition of average laser power of 10 W, laser scanning pitch of 15 μm, laser scanning speed of 6 mm/s and oxygen-rich atmosphere, the effect of laser-induced oxidation is optimal. A loose oxide layer and a sub-layer with the hardness of 160 ± 40 HV are generated where the composition of the oxide layer is mullite (2Al2O3·SiO2). Comparative investigation on the cutting force, surface quality and tool wear are performed. Compared with the conventional milling (CM), the normal force and thrust force of LOM decrease by 39% and 55%, respectively. The reduction of cutting forces is attributed to thermal failure of the interface layer. The dominant surface defects of the machined surface are particle fracture, particle pull-out, matrix tearing and matrix coating. Among the investigated parameters, the minimum surface roughness Sa is 0.37 μm when the feed per tooth and the cutting depth are 0.005 mm/z and 0.2 mm, respectively. The dominant tool wear modes of LOM include diamond spalling and edge chipping. The tool wear modes of CM are diamond spalling, edge chipping, abrasive wear, and adhesive wear. LOM can prolong the tool life and achieve better surface quality under the same cutting length.