Reliability-based residual life prediction of large-size low-speed slewing bearings

•A residual life prediction approach for large-size slewing bearings is proposed.•The periodicity of load distribution over the raceway is discussed.•The fixed ring of a slewing bearing wears much faster than the rotatable ring.•The soft area of a fixed ring wears the fastest due to inadequate heat treatment.•Proposed life prediction model is verified by an accelerated life test and ISO281.

Critical failure of a slewing bearing used in large machines would bring disastrous loss to an enterprise. Accurate residual life prediction of a slewing bearing can reduce unexpected accidents and unnecessary maintenances. In this paper, a residual life reliability prediction approach for slewing bearings was firstly presented based on the Weibull distribution. Afterwards, a novel approach for parameter estimation was proposed based on a small-sample test, which built the relationship between the characteristic life of a slewing bearing and the maximal load over the raceway. To verify the proposed approach, a full-load accelerated life test was implemented on a QNA-730-22 slewing bearing. It was observed that the damage of the outer (fixed) ring caused the failure of the slewing bearing, while the inner (rotatable) ring was still in good condition. After which, the residual life prediction model was then established by the proposed approach. Compared to ISO 281 and NREL design guide 03, the proposed approach is closer to engineering practice, and thus has the potential for slewing bearing prognostics.