How to Reduce the Noise of Tapered Roller Bearings?

The Bearings are indispensable for mechanical operation, but they also have inherent shortcomings that cannot be overcome. Bearings are one of the sources of mechanical noise. So, how can we reduce the noise of tapered roller bearings? Exploring the mechanism of bearing noise and studying comprehensive control during the production process are key to improving bearing quality and achieving technological innovation. Compared with other types of products, the structure, performance, and noise generation mechanism of tapered roller bearings have their uniqueness.

Bearings inevitably generate vibration during operation, which is caused by external factors on the one hand. It can be seen that the key to solving the bearing noise problem lies in addressing the vibration of the bearings.

First, the dimensional accuracy, form and position accuracy, and surface quality of each tapered roller bearings component should meet the technical conditions of the corresponding accuracy grade; identify the main noise sources and focus on solving them during the processing. When the bearing rotates, the cage is in a free-floating state. To reduce the axial movement of the cage, the length of the window holes should be produced according to the lower deviation of the size. At the same time, to reduce the friction noise between the cage and the rollers, surface polishing and phosphating treatment must be carried out. In addition, when shrinking the cage, it should be tightened as much as possible without affecting the rotational flexibility of the bearing. During processing, inspection, assembly, and storage and transportation of bearing components and finished products, operating procedures should be strictly followed to avoid adverse consequences such as bumps, deformation, and corrosion. Meanwhile, the assembled finished products must be thoroughly cleaned to remove dust and adhesions, ensuring cleanliness.

When the tapered roller bearings rotates, the raceway surfaces of the inner and outer rings, due to rolling contact with the rolling elements, form dark running tracks. The presence of these tracks on the raceway surfaces is not abnormal and can indicate the load conditions. Therefore, when disassembling the bearing, pay close attention to and observe the running tracks on the raceway surfaces. Careful observation of the tracks can reveal whether the bearing is subjected to purely radial loads, large axial loads, moment loads, or extreme rigidity unevenness in the bearing housing. This can help check for unexpected loads on the bearing, excessive installation errors, etc., and serve as a clue to investigate the causes of bearing damage.

Lubrication is crucial, not only for tapered roller bearings but for all bearings. However, please note that bearings should not be filled with excessive grease. Then there is the replacement of bearing lubricants. For bearings lubricated with oil, after draining the old oil, if possible, fresh oil should be poured in and the machine should be run at low speed for a few minutes. This allows the oil to collect residual contaminants as much as possible, which are then drained. When replacing the grease in grease-lubricated bearings, the removal tools should avoid contact with any part of the bearing using cotton-based materials. Residual fibers may wedge between the rolling elements and cause damage, especially for applications with small bearings, where this issue requires extra attention.

1. Crest Factor Diagnosis Method

The crest factor is defined as the ratio of the peak value to the root-mean-square value. It is a dimensionless parameter, and its advantage in diagnosing tapered roller bearings is that it is not affected by the geometric dimensions, rotational speed, and load of the rolling bearings, nor by the sensitivity of the sensor. The crest factor is suitable for diagnosing point-type faults.

Application method: Monitor the trend of the crest factor over time. Generally, it is empirically considered that when a rolling bearing is normal, the crest factor is approximately 3–5; when the bearing is damaged and the damage progresses, the crest factor significantly increases, exceeding 3–5 and possibly reaching 10–15; when the fault is severe, the crest factor returns to 3 again.

2. Kurtosis Diagnosis Method

Kurtosis is defined as the normalized fourth central moment. It is also a dimensionless parameter, and its advantage in diagnosing rolling bearings is that it is not affected by the geometric dimensions, rotational speed, and load of the rolling bearings, nor by the sensor sensitivity. Kurtosis is also suitable for diagnosing point-type faults.

Application method: Monitor the trend of kurtosis over time. Generally, it is empirically considered that when a rolling bearing is normal, the kurtosis is approximately 3; when the bearing is damaged and the damage progresses, the kurtosis significantly increases, even reaching dozens; when the fault is severe, the kurtosis falls back to around 3 again.

For more information, feel free to contact QIBR