Implications for chip segmentation on milling force and vibration

AbstractTraditional approaches for predicting dynamic stability of machining processes are based on mechanistic force models that assume constant force coefficients for a selected combination of process parameters and the structural dynamics. However, increasing evidence of dynamically varying cutting forces due to cyclical chip formation suggests that constant force coefficients may not be sufficient and time-dependent, or dynamic, coefficients may be warranted. Based on prior in-situ characterization of chip segmentation frequency and its dependence on machining parameters during orthogonal cutting of Ti-6Al4V alloy, we propose the addition of a time-dependent term to the current mechanistic cutting force model. Given the new force model, the effect of the time-dependent term on milling stability is evaluated numerically. The results show that when the natural frequency for the tool tip frequency response function is near the chip segmentation frequency, the stability boundary is altered. Otherwise, it is not. Based on this preliminary study, future work will be carried out to validate the model predictions. This could have implications for metal removal rates and productivity by leveraging materials-informed simulation of machining dynamics.