Cutting Force Mechanisms in Drilling 90MnCrV8 Tool Steel: ANOVA and Theoretical Insights

This study investigates the influence of tool geometry and cutting parameters on thrust forces and process stability during the drilling of 90MnCrV8, a hard and wear-resistant tool steel. The objective was to identify the dominant and interactive effects of feed per revolution (frev), nominal tool diameter (D), cutting speed (vc), and geometry angles (εr, αo, ωr) on the thrust force (Ff). Experimental data were evaluated using analysis of variance (ANOVA) to determine statistical significance and effect size (η2), supported by theoretical models by Kienzle, Merchant, Oxley and Zorev to explain observed physical trends. Feed per revolution had the most decisive influence on thrust force (η2 = 0.690; p < 0.001), followed by tool diameter (D; η2 = 0.188). Geometric parameters showed secondary yet significant effects, mainly on stress distribution and chip evacuation. The interaction between D and frev produced a multiplicative force increase, while the combination of frev and helix angle (ωr) reduced friction at higher feeds. Cutting speed had a minor effect (η2 = 0.007), suggesting limited thermal softening. The findings confirm that drilling hard steels is primarily governed by the energy of plastic deformation.