Self-excited vibration of workpieces in a turning process

Vibration occurring during machining is a major limitation to the productivity and quality of products. The dynamic interaction between the cutter and the workpiece during a turning process causes self-excited vibration. If the level of vibration is sufficiently high, poor surface quality of the workpiece and excessive tool wear can occur. This article presents a dynamic model for the vibration in turning operations taking into account the time-dependent reduction of workpiece diameter and the regenerative chatter mechanism. The workpiece is modelled as a beam rotating about its longitudinal axis and the cutter provides a moving load that is a source of parametric excitation. Simulated numerical examples are presented. Turning experiments are conducted that demonstrate vibration and chatter in turning operations. It is found through comparison between the theoretical and numerical results that the established dynamic model can predict the vibration pattern of the workpieces fairly well but underestimates the magnitude of workpiece oscillation.