Analysis of an Angular Contact Ball Bearing Failure and Strategies for Failure Prevention

Bearing failures are one of the most common failure modes in the rotating machinery and equipment. Angular contact ball bearings are widely used considering their ability to carry the loads in both axial and radial directions, durability and low friction. The smooth functioning of these bearings greatly depends on the bearing load rating, material, type of fit with which it is assembled, the operating temperature and proper installation in the assembly. This paper presents the analysis of a failure of an angular contact ball bearing used in the gas motor system of an electrohydraulic control actuator used for launch vehicle attitude control. Detailed investigation of the failure is carried out by thermal and structural modeling of the bearing assembly, and the failure cause is identified as the combination of design error, hardware deviations and improper assembly operation which led to bearing misalignment and very high loading of the first row of balls resulting in excessive heating. The failure theory explains all the observations on the parts of the failed bearing. The physics of failure is understood, corrective actions to avoid the failure are addressed, and the strategies for prevention of similar failures are evolved.