Acoustic emission spikes at workpiece edges in grinding: Origin and applications

Acoustic emission signals from interrupted machining operations exhibit spikes at workpiece entry and exit, which are particularly conspicuous in grinding. Although their occurrence has been widely reported, these spikes are yet to be clarified in terms of their origin or interpreted to yield useful process information. This paper hence reports on the analyses of time-averaged and raw acoustic emission signals from surface grinding, with reference to burr formation as well as dynamic and thermal effects, in order to elucidate this intriguing phenomenon. The transient spikes at the entry and exit are shown to be a consequence of the wheel establishing and losing contact with the work over the actual contact length, in terms of heat conduction and damping, which are reflected in characteristic frequency bands of the AE signal. The research is demonstrated to have consequently yielded a simple, non-destructive method for assessing the actual wheel–work contact length in grinding.