Identification of Chip Formation Mechanism through Acoustic Emission Measurements

Summary This paper deals the nature of the acoustic emission which is radiated from the cutting point in metal cutting, and deals the relationship between the mechanism of chip formation and the acoustic emission signals. Various workpiece materials were machined by turning and milling using sharp and worn cutting tools, and two acoustic emission(AE) signals were measured simultaneously, one was detected at the shank of the cutting tools and the other was detected at the workpieces. It was found that the two AE signals have quite different nature, that is, the former contains the information about the sliding at the tool-chip interface and the latter bears the information about the sliding at the flank surface, the latter also includes the information on the deformation or fracture of the shear plane. The influence of the BUE on the AE was discussed. Further, the AE signals of saw-toothed and discontinuous chip formations were measured using stainless steel, Titanium alloy and brass as workpiece materials, and the mechanisms of these chip formations are discussed considering the nature of the acoustic emissions. Finally, it was clarified that the power spectrum of the AE signals which is measured at the tool side shows a characteristic pattern by the workpiece materials, and it is remarkably affected by the tool wear.