Through macroscopic and microscopic analysis, it can be concluded that the deformation marks on the surface of the inner ring raceway are biased towards the retaining edge; The working surfaces of the bearings are all burned; Cracks appear on the surface of the ring, while plastic deformation occurs on both the inner ring and roller surfaces, especially in the plastic deformation zone of the inner ring, where there are numerous small cracks. The above phenomenon indicates that the bearing deteriorated due to burns on the working surface, resulting in cracks and fracture failure. Therefore, it can also be determined that the failure mode of the bearing is thermal cracking. Mechanical equipment is used under harsh working conditions such as heavy loads, large impact loads, and high levels of dust. The bearing deviates during operation, resulting in insufficient internal clearance. Due to the limitation of movement space, the automatic centering function of the bearing is affected, resulting in uneven bearing force. One side of the roller and raceway are compressed, causing excessive local load on the bearing. The squeezing friction between the roller and the raceway generates a large amount of frictional heat, and the lubricating oil cannot take away more heat, resulting in an increase in the temperature of the roller and the inner and outer rings. The temperature rise of the bearing in turn destroys the formed lubricating oil film, resulting in dry friction between the rollers and the ring, generating more and more heat that cannot be dissipated. The temperature of the inner and outer rings and the rollers rises sharply, especially the temperature of the near surface layer of the inner ring raceway exceeds the austenitization temperature in a short period of time, causing the near surface layer of the inner ring raceway to undergo secondary quenching. The increase in temperature during bearing operation causes changes in the structure and strength of the material. When the stress (including thermal stress caused by secondary quenching) exceeds the tensile strength of the material, cracks will appear. In the subsequent operation, the crack propagates until it fractures.