Effect of Defect Size and Load on the Performance of Thermoplastic Bearings

Abstract The dynamic performance of thermoplastic bearing with respect to defect size, location, applied load, and speed was investigated in this article. A fatigue test rig was developed in house to test the thermoplastic bearing. The vibration signals are measured continuously using a piezoelectric accelerometer to investigate the influence of the size and location of the defects of both polypropylene (PP) and polyoxymethylene (POM) bearings. Vibration signatures of metallic bearings are investigated and compared with thermoplastic bearings. Test results reveal that POM bearings exhibit less vibration amplitude compared to that of PP and metal. Peak vibration amplitudes of shaft harmonics and Fast Fourier Transform increase with respect to the load levels and are more pronounced in inner race defects compared to outer race defects and are found to increase with the increase in defect size. A statistical indicator kurtosis shows the sensitivity to bearing damage by analyzing the vibration signals of the thermoplastic ball bearing. Thermoplastic bearing failure under high loads reveals wear and smearing as the important failure modes.