Finish-machined high-volume-fraction SiCp/Al (SiC-particle-reinforced Al matrix) composites tend to have poor surface roughness. To explore the effects of various parameters on the surface roughness of these materials, an orthogonal experiment array L16 (4)4 was designed based on the tool nose radius, cutting depth, feed rate, and cutting speed. Surface roughness values were obtained using a TR200 portable roughness metre during finishing cutting experiments, which were conducted on a Mazak CNC lathe. The Taguchi approach and analysis of variance were used to analyse the significance of the various parameters. A model was developed based on a polynomial regression equation to predict the optimum surface roughness and its corresponding parameters. The confirmation experiments showed that there was good consistency in the optimum surface roughness between the predicted and experimental results. © 2020, King Fahd University of Petroleum & Minerals.