Investigation of the milled surface quality of SiCp/Al composite materials with a moderate SiCp volume fraction

Silicon carbide particle–reinforced aluminum matrix (SiCp/Al) composite materials are challenging to machine, leading to significant surface quality issues arising during milling. In this study, a single-factor experiment was conducted using carbide-coated tools to mill SiCp/Al composite materials with a 45% volume fraction of silicon carbide particles (SiCps). Scanning electron microscopy, roughness measuring instruments, and a three-dimensional optical profiler were employed to investigate the formation mechanisms of the machined surface morphologies, as well as the effects of milling parameters (milling speed, feed per revolution, and milling depth) on the surface micro-morphology of the SiCp/Al composite materials. This study assessed the suitability of various roughness characterization parameters for evaluating the milled surface of SiCp/Al composite materials, including the two-dimensional profile arithmetic mean deviation (Ra), profile root mean square deviation (Rq), and microscopic surface roughness 10-point height (Rz), as well as the three-dimensional arithmetic mean deviation of the surface profile (Sa), and root mean square deviation of the surface profile (Sq) roughness characterization parameters to evaluate the milled surface of the SiCp/Al composite materials. The findings suggest that the three-dimensional roughness characterization parameters more accurately reflected the changes in the surface roughness than the two-dimensional ones. When the milling speed increased from 0.05 to 1.2 mm/rev, Sa first decreased from 0.514 to 0.498 µm and then increased to 0.537 µm, while Sq first decreased from 0.637 to 0.616 µm and then increased to 0.658 µm. Ra, Rz, and Rq all increased with higher values of feed per revolution and milling depth.