What are the stages of spherical roller bearing cage damage?

Spherical roller bearings are prone to damage and wear due to friction during operation, especially when operating under high temperatures, which makes the cage more vulnerable. Based on the degree of damage, bearing failure can be divided into four stages. Therefore, the bearing cage must have good thermal conductivity and a low friction coefficient to reduce the rate of damage.

Stage 1: Fault Initiation

In this stage, the spherical roller bearing temperature, noise, and overall vibration velocity remain normal, with no significant change in vibration spectrum. However, there are initial signs of damage, as the peak energy level and its frequency spectrum show some abnormalities, indicating the early signs of failure. The bearing fault frequency appears in the ultrasonic range, approximately 20-60 kHz. Although the fault is not yet obvious, it can be detected with careful monitoring.

Stage 2: Early Fault

At this stage, the temperature remains normal, but there is a slight increase in noise and overall vibration velocity. The vibration spectrum shows little change, but the peak energy increases significantly, and the spectrum becomes more prominent. The bearing fault frequency ranges from approximately 500 Hz to 2 kHz. Although the fault is not yet serious, it is important to pay attention to it. Maintenance recommendations include enhancing monitoring and preparing for further inspections.

Stage 3: Noticeable Fault

At this stage, the bearing temperature starts to rise slightly, and noise becomes audible. The overall vibration velocity increases significantly, and the vibration spectrum clearly shows the bearing fault frequency along with its harmonics and sidebands. Additionally, the noise floor in the vibration spectrum increases, and the total peak energy becomes much higher compared to stage 2. The fault frequency falls within the 0-1 kHz range. It is recommended to replace the spherical roller bearing towards the later part of this stage, as visible wear and tear may already be evident, and continuing to run the bearing will lead to more serious failures.

Stage 4: Catastrophic Fault

In the fourth stage, the bearing temperature rises significantly, and noise intensity, vibration velocity, and vibration displacement increase notably. The fault frequency in the vibration spectrum starts to disappear, being replaced by stronger random wideband high-frequency noise. The total peak energy increases rapidly, and instability may occur. At this point, the spherical roller bearing must not be allowed to continue running, as catastrophic damage may occur. To avoid extreme failure, the equipment must be stopped immediately, and the bearing should be replaced.

Conclusion

The degree of damage to the bearing cage varies at different fault stages. In practice, bearing faults cannot be completely prevented, but they can be minimized through effective monitoring and timely replacement. Especially after stage 3, it is recommended to replace the spherical roller bearing to prevent further deterioration of the fault and avoid catastrophic damage.

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