This document reviews research on optimizing CNC turning process parameters to minimize surface roughness. It summarizes 10 research papers that studied the effects of cutting speed, feed rate, depth of cut, cutting tool type, and cooling conditions on surface roughness when turning various materials like steel, aluminum, and titanium. The document finds that feed rate typically has the largest effect on surface roughness, followed by cutting speed, while depth of cut has a smaller impact. It recommends using techniques like Taguchi methods, response surface methodology, and ANOVA to determine the optimal process parameters that achieve the minimum possible surface roughness.