Ultrasonic measurement for surface damage monitoring in coated bearing shells

Aluminium and other soft metal coated plain bearings are common in high-speed rotating machines due to their light weight and high performance. This makes the monitoring of bearing surface condition an important requirement to ensure healthy machine operation. In this paper, an ultrasound-based technique is investigated to measure the wear condition of thin aluminium bearing coatings. High-frequency 22 MHz piezoelectric sensors were selected based on both numerical simulations and experiments. Tests were performed on four groups of samples with artificial damage and three groups of samples worn by dry running. The results have shown the deviation between ultrasound measurement and microscope measurement are within 5 μm for artificially damaged samples and within 15 μm for samples worn under dry running conditions.