Study on acoustic emission in machining hardened steels Part 2: Acoustic emission during continuous chip formation with a non-overlapping cutting arrangement

Abstract The sources of acoustic emission (AE) in the machining of hardened steels have been investigated using a novel ‘non-overlapping’ cutting technique, in which the depth of cut increases with tool path. The relationship between AERMS and depth of cut was found to vary considerably; depending on work material hardness and cutting speed, AERMS may increase, remain constant or decrease with increases in depth of cut. The lack of proportionality between AERMS and the combined work rate of plastic deformation and sliding friction contrasts with the current models of AE in metal cutting, for which plastic deformation and sliding friction are assumed to be the dominant sources of AE. In considering the nature of AE in metal cutting, particular attention is given to the transition from rubbing to chip formation (due to increasing depth of cut), the structure of continuous type chips and the propagation of AE through the shear zones.