An Investigation of Variable Spindle Speed Face Milling for Tool-Work Structures With Complex Dynamics, Part 1: Simulation Results

Abstract

A mechanistic dynamic model is used to simulate a face milling process during constant and variable speed machining. The model can be used to predict the optimum speed trajectory that can provide a low level of vibration and consequently a large productivity rate and a small surface error. The model is used to investigate the vibration of face milling processes that have one, or multiple coupled modes of vibration acting throughout the cut. For cutting processes having one dominant mode of vibration, the model predicts that variable speed machining is especially effective over constant speed machining when the tool-work system changes its dominant mode of vibration throughout the cut, or when the tool-work system has several modes of vibration coming from component parts that are cut in the same time. For cutting processes having multiple dominant modes of vibration, the model predicts that variable speed machining is especially effective over constant speed machining when the tool-work modes of vibration are unequal and moderately coupled to each other. Also, the model suggests that for tool-work systems having complex geometries with dynamics hard to predict, variable speed machining is safer to use than constant speed machining when trying to achieve high productivity rates. This is due to the fact that variable speed machining is robust with respect to the dynamics of the tool-work system. Finally, the model predictions are in good agreement with the experiment.