Lathe stability charts via acoustic emission monitoring

Signal parameters characterizing acoustic emission (AE) detected during metal cutting have been theoretically correlated in a simple manner, to the work material properties, cutting conditions, and tool geometry. During chatter, the cutting conditions and the tool geometry change considerably. Self-exited chatter, an instability of the cutting process in combination with the machine structure, is a basic performance limitation of machine tools. In the research findings presented in this paper, changes occurring to AE signal parameters have been used to detect the onset of chatter and hence plot stability charts, during a turning operation. Apart from showing the borderlines of stability, such charts can be used to identify the necessary changes required to eliminate chatter at minimum or no loss of production. The signal parameters investigated include AE mean intensity level, the skew and kurtosis of the power spectrum; as well as the count rate of the emissions.