Analysis of acoustic emission signals and surface integrity in the high-speed turning of Inconel 718

Abstract

Acoustic emission (AE) signals from the machining deformation zone have been used in the past to monitor and study the cutting tool wear and failure, the chip formation mechanism, and the machined surface quality on work materials other than Inconel 718. The machined surface quality generated during the machining of superalloys is a function of the deformation process that occurred in the machining zone. It is known that the interaction between the machining parameters, the cutting tool, and the work material characteristics govern the deformation process. AE signals are capable of capturing the deformation zone activities and hence it is felt that an analysis of the AE signals during machining could help to determine the quality of the machined surface. Therefore, in this work, the dependence of the machining deformation on the surface generation mechanism was assessed in terms of the energy, number of counts, and mean frequency amplitude of the AE signals. Further, the AE characteristics were analysed as a function of the cutting speed, feed rate, depth of cut, and tool edge geometry. The analysis revealed that the frequency amplitude of the AE signals is influenced by the cutting speed. The feed rate and edge geometry are found to influence the number of counts generated during machining deformation. AE signals with fewer perturbations in the energy and counts profiles indicate a better-quality surface with the least alterations. Thus, in general, the AE signal variations have been found to be useful to correlate abnormal events during machining, such as higher thrust forces, chip form variation, and surface anomalies produced in the machining of Inconel 718.