Experimental investigation of correlation between attrition wear and features of acoustic emission signals in single-grit grinding

The cutting performance of grit is controlled by its shape and geometric parameters. However, the geometry changes with the progression of attrition wear, thereby increasing grinding temperature, grinding force and decreasing grinding efficiency. It is important to monitor the cutting condition of grit to confirm its state of wear. Acoustic emission (AE) signals have been widely used in monitoring cutting tool conditions and have been proven effective in detecting tool wear and failure. To identify the correlation between attrition wear and AE features, comparison tests were carried out with a pair of sharp and blunt grits scratching on hardened AISI4340 workpiece and the AE signals during the scratching process were obtained. The signals were analyzed in the time, frequency, and time-frequency domain The numbers of AE counts in the time domain differed for the sharp and blunt grits. It is also found that the proportions of AE energy in the frequency band of 0–90 kHz and 90–250 kHz differed was attributed to differences in strength of the various AE sources. The AE energy was further analyzed in time-frequency domain using discredit wavelet transform (DWT). The AE energy at certain decomposition level was extracted. A validation test was carried out with a worn grit. It was suggested that features associated with AE energy are appropriate for detecting attrition wear of grit, but the number of AE counts fluctuated owing to the complex friction behavior of the worn surfaces. The results of AE energy distribution in the time-frequency domain reveal that the amplitude of the AE energy deteriorates more rapidly when the grit is worn.