A Feasibility Study of On-Line Identification of Chatter in Turning Operations

The Dynamic Data System approach has been used to develop an identification scheme for chatter in turning. The purpose of developing this simplistic scheme was to enable its easy implementation on a microprocessor so that on-line identification could be accomplished. It has been shown that the stochastic models are capable of following the changing parameters of the process. The modal parameters of the dominant modes are determined along with the relative contribution of each mode to total power of the analyzed output signal from the machining process. Based on this information the mode susceptible to chatter is identified and as a simple index of stability the modal damping ratio or equivalently the magnitude of the root of the characteristic equation introduced. The theoretical postulations were confirmed experimentally for three different states of the turning process, namely, stable cutting conditions, transient state when chatter started to develop and finally fully grown chatter vibrations.