The Effect of Cage and Roller Slip on the Measured Defect Frequency Response of Rolling-Element Bearings

Abstract

The paper reports the effect of cage and roller slip on the measured defect frequency response of rolling-element bearings using high-frequency resonance technique (HFRT) as a survelliance module. The differences in theoretically calculated and experimentally determined defect frequencies have been used to identify percentage cage slip and roller slip in various bearings under no-load and load conditions at different speeds of operation. Various defect frequencies and their energy levels are used to monitor the severity of defects and complex response interactions of rolling elements with inner and outer rings of the bearings. It is shown that negative cage and roller slip is predominant at moderate speed under no-load and load operation. Positive slip is significant at high speed under no-load operation. Negative cage and roller slip is indicated by the presence of outer-race linear defect frequency along with rolling-element defect frequency, whereas positive slip is shown by inner race accompanied with rolling-element defect frequencies. Energy levels of identified defect frequencies are greater under no-load as compared to operation under load for new bearings at all speeds of operation. However, for defective bearings, this pattern is reversed at rated and high speeds of operation. In general, percentage negative cage slip is found to be more than the corresponding roller slip and percentage positive cage slip is less than corresponding roller slip. Under load at rated speed, cage and roller slip is minimum for new bearings. However, the slip is still identified by defect frequency response. The investigations reported in the paper may prove to be a potential tool to diagnose the complex response interactions in rolling-element bearings.