Research on prediction of milling force in laser assisted milling of SiC_f/SiC composites

The milling process of SiC_f/SiC composites is characterized by high cutting forces and challenging quality assurance, rendering them a typical difficult-to-machine material. In this study, multiple linear regression is adopted to establish predictive models for tangential force F_x and radial force F_y in both laser-assisted overall milling and sequential milling (transition layer/ablation layer). The effects of spindle speed, feed per tooth, and laser power on milling forces are systematically investigated. Experimental validation demonstrates that the average relative error of each model remains below 5%, with coefficients of determination (R²) exceeding 0.86. Integrating microscopic surface morphology analysis with strain-rate hardening theory and material removal mechanisms, the influence mechanisms of process parameters on milling forces are elucidated. The results reveal that F_x increases with spindle speed owing to the strain-rate hardening effect; laser power exhibits a positive correlation with F_x in LAAM(S T) due to the thermal insulation effect of the ablation layer and the phase-transformation gradient within the transition layer, whereas its influence is negligible in LAAM(O) and LAAM(S A). As the cutting mechanism transitions from "indentation fracture" to "shear slip", an increase in feed rate elevates the force within the ablation layer due to the enlargement of the indentation fracture volume, yet reduces the force within the transition layer and loose powder layer as the shear-slip mechanism becomes predominant.