Effects of cutting conditions on excitation and dynamic stiffness in milling

The effect of cutting conditions on vibration has a great significance on machining parameter selection and active vibration control. Cutting parameters affecting vibration, such as spindle speed, feed rate, and axial depth of cut, have been studied by many researchers, but the study on effect mechanism of radial depth of cut on vibration remains deficient. Radial depth of cut may change the cutting teeth, which has a great influence on vibration. This paper proposes a method to study the effect mechanism of radial depth of cut on cutting vibration based on excitation and dynamic stiffness. The dynamic model from the perspective of the contact between teeth on the cutter (TC) and the workpiece is built. The number of cutting teeth on the cutter (NCTC) is expressed as radial depth of cut; then, the bandwidth and energy of excitation at different radial depths of cut are deduced by the theory of cutting dynamics. The variation of the machine-tool-workpiece system (MTWs) dynamic stiffness at different radial depths of cut is estimated with the measured output responses and cutting force excitation. The accuracy of effects is checked by a time and frequency domain analysis of cutting force and vibration measured in the cutting tests. The results show that cutting force excitation and MTWs dynamic stiffness are significantly affected by the radial depth of cut, which are consistent with the mechanism analysis. Moreover, the effectiveness of the effects is verified by the machined surface profile.