Causes and Symptoms of Cage Damage in Crossed Roller Bearings

The primary function of the cross-roller retainer is to guide and drive the rolling elements to roll correctly along the raceway, evenly spacing them at regular intervals and ensuring smooth rolling between the inner and outer rings. It also helps improve the lubrication conditions inside the bearing and prevents the rolling elements from falling out. Once a failure occurs, it can adversely affect the bearing’s performance. Below, our Ovite editor will introduce you to the causes and symptoms of damage to cross-roller bearing retainers.

I. Manifestations of Damage to the Cage of Crossed Roller Bearings

1. Damage to the retainer includes deformation, breakage, and wear of the retainer.

2. Damage to the bearing column:

3. Deformation of the end face:

4. Wear on the concave surface:

5. Wear on the guiding surface:

II. Causes of Damage to Crossed Roller Retainers

1. Consideration of the bearing’s own angle

Generally speaking, when a bearing has low rotational accuracy, a small clearance, and the rolling mill operates at a high linear speed—approaching or even exceeding the bearing’s maximum allowable speed—it can lead to excessive bearing temperatures, followed by a series of problems such as abnormal noises, seizing, and galling. In this particular incident, the damaged bearings were concentrated on the operator’s side, whereas the bearings on the drive side, which used the same batch of bearings and operated under identical speed and lubrication conditions, showed no such issues and continued to function normally. Therefore, we can temporarily rule out the possibility that the bearing damage was caused by inherent defects in the bearings themselves.

2. Dimensional fit

The cross roller bearing is installed on the operating side of the roll system, primarily to limit the axial movement of the shaft and not to bear any radial loads. The outer diameter of the bearing is fitted with the housing bore using an F7 tolerance, while the inner diameter is fitted with the shaft diameter using an e6 tolerance. The main bearing has a radial clearance in the C3 group. According to calculations, under this fit, when the bearing is subjected to radial forces during operation, some of these forces will be transferred to the main bearing. Therefore, it can be temporarily ruled out that the bearing damage was caused by dimensional fit issues.

3. Issues with mating of surface-contact components

Upon careful examination of the inner and outer race surfaces of the bearing, it was found that most damaged bearings exhibit abnormal wear on these surfaces. The retainer also shows severe wear marks. Further inspection of the mating surfaces in contact with the bearing reveals abnormal wear on several components: specifically, the flange surface of the outer race retainer, the surface of the spacer ring that connects to the inner race, and the boss surface within the housing bore that locates the outer race—all of which display pitting and burrs on their surfaces.

From this, it can be determined that during operation, the bearing experiences severe relative sliding friction with all mating components. Measurements reveal that after installation, the outer ring of the bearing is not tightly pressed axially, leaving a gap of 0.5 to 0.7 mm. Similarly, after the inner ring is locked, a significant axial gap still remains. Consequently, the bearing exhibits considerable axial play during operation. Since the hardness of the various components is lower than that of the bearing itself, they are prone to irregular wear. When the bearing is subjected to an axial force in one direction, its contact surfaces—already irregularly worn—come into contact with the opposing mating parts, causing the inner and outer rings of the bearing to tilt relative to each other. As a result, at higher speeds, the rolling elements experience irregular motion, generating substantial clamping forces on the cage and frequent impact forces, which in turn lead to wear and fracture of the cage.

The above is an introduction to the causes and symptoms of cage damage in crossed roller bearings. We hope this information is helpful to you. In addition, Aowei Bearing manufactures crossed roller bearings and turntable bearings of various specifications. If you have any needs, please feel free to call us for further inquiries.