Quadratic Response Surface Modeling of Surface Roughness in CBN Grinding of HARDOX 500

Abstract

This study investigates the influence of grinding parameters on surface roughness (Ra) in grinding HARDOX 500 steel with a CBN wheel, using a quadratic Response Surface Methodology (RSM). A full quadratic model, including linear, interaction, and squared terms, was initially developed and subsequently simplified through stepwise selection based on the Akaike Information Criterion (AIC). The full model achieved R² = 0.987 and adjusted R² = 0.964, while the simplified model achieved R² = 0.985 and adjusted R² = 0.974, indicating strong predictive capability with reduced complexity. Analysis of variance (ANOVA) and partial effect size (η²) revealed that the squared term of depth of cut (t²) exerted the dominant and statistically significant influence on Ra (p < 0.001). In contrast, spindle speed, feed rate, and their higher-order terms played only minor or negligible roles. Diagnostic plots confirmed model adequacy, with residuals evenly distributed and predicted values closely matching experimental data. The findings highlight that precise control of depth of cut is the key factor in achieving the desired surface quality when grinding HARDOX 500 steel, providing practical guidance for optimizing process parameters in industrial applications.