Tool Condition Monitoring using Acoustic Emission and Vibration Signature in Turning

The various sensors used to monitor tool condition usually sense the cutting tool state in terms of electric/magnetic/optical signal by responding to the change of process dynamics during machining. The redistribution of energy that is released from the localized sources, i.e. stress and strain developed in machining, generates the transient elastic wave inside the workmaterial and cutting tool known as, the acoustic emission (AE). The changes in cutting condition produce vibration in the system and thus affect the cutting tool state. Therefore, investigating the tool condition using the acoustic emission and vibration signature would be an effective approach. In this study, an acoustic emission sensor and a tri- axial accelerometer have been placed on the shank of the cutting tool holder to monitor the cutting tool condition in machining. The acoustic emission sensor assesses the internal change whereas the vibration sensor demonstrates the external effect on tool state. The RMS signals and Fast Fourier transform (FFT) are used to illustrate the output of sensors. For this particular investigation, the experiment shows that the AE and vibration components can effectively respond to the tool state and the different occurrences in turning. The AERMS represents the rate of tool wear progression whereas the feed directional vibration component (VX) corresponds to the surface roughness in turning. The vibration components, Vx, Vy and Vz change with feed rate, depth of cut and cutting speed respectively. The amplitude of vibration components decreases with the increase of cutting speed, and increases with the increase of feed rate and depth of cut; which support the nature of tool wear in turning. Even though the maximum intensity of signal frequency fluctuates at the different state of tool wear and at different cutting conditions, the frequency of vibration components always lies within a band of 0 Hz - 41 kHz, and the AE varies between 56 kHz and 581 kHz.