This work presents a comprehensive experimental study on the effects of cutting parameters on surface roughness (Ra) during high-speed milling of stainless steel 304 and aluminum alloy A7075, two widely used engineering materials with distinct mechanical behaviors. Cutting speed (V: 190–380 m/min), feed per tooth (S: 0.1–0.3 mm/rev), and depth of cut (t: 0.5–1.5 mm) were systematically varied according to a full factorial design to investigate their individual and interactive influences on Ra. Surface roughness measurements were conducted using a high-precision Mitutoyo SJ-410 system. Regression analysis and ANOVA were employed to develop predictive models and evaluate the statistical significance of each parameter. The resulting models exhibited high predictive accuracy, with adjusted R 2 values of 0.9690 for 304 stainless steel and 0.9672 for A7075 aluminum, indicating strong reliability. The analysis revealed that Ra decreases with increasing cutting speed and increases with higher feed rate and depth of cut. Cutting speed was identified as the most influential factor, followed by feed rate and depth of cut. Comparative results demonstrated that A7075 consistently produced smoother surfaces, with Ra values 25–30% lower than those of stainless steel 304, due to its lower hardness, better chip evacuation, and higher thermal conductivity. Conversely, 304 stainless steel exhibited higher surface roughness as a result of pronounced work hardening and tool adhesion during cutting. These findings provide critical guidelines for selecting optimal cutting parameters—high cutting speed, low feed, and moderate depth of cut—to achieve superior surface quality, and they establish a foundation for multiobjective optimization in high-speed precision milling applications.
Pham et al. (Sat,) studied this question.