Mechanistic force model for drilling of bulk metallic glasses with numerically optimized cutting coefficients

This study presents a mechanistic force model for predicting thrust force and torque during the drilling of Zr-based bulk metallic glasses (BMGs), known for their high hardness and poor machinability. The proposed model discretizes the twist drill into elementary cutting tools along the lips and treats the chisel edge separately to account for its distinct plowing-dominated behavior. Cutting force coefficients for both regions were identified using a nonlinear optimization routine based on experimental drilling data, avoiding the need for orthogonal cutting tests. The model was validated across twelve different cutting conditions, demonstrating its ability to capture nonlinear effects of feed rate and spindle speed. The average prediction errors were 5.5% for thrust force and 8.8% for torque. These results confirm the model’s robustness and suitability for predictive simulation and force monitoring in precision drilling of hard-to-machine amorphous materials like BMGs.