The Impact of Fatigue Pitting on Bearing Troubleshooting
The company mainly produces three core series of products: cylindrical roller bearings, self-aligning roller bearings, and thrust self-aligning roller bearings. The product can be adapted to multiple industrial fields such as metallurgical equipment, mining machinery, heavy machinery, engineering equipment, etc., and can meet the operational and load-bearing requirements of equipment under different working conditions.
SZ Bearings
When the rolling elements are subjected to a load, contact stress develops at the contact surfaces between the rolling elements and the inner and outer rings. Since the inner and outer rings and the rolling elements undergo relative rotational motion during operation, causing the contact stress to fluctuate. When the contact stress exceeds the specified limit, fatigue cracks form beneath the surface and gradually propagate to the surface, leading to fatigue pitting on the surfaces of the inner and outer rings and the rolling elements. This results in a loss of rotational precision, increased noise, and heightened shock and vibration in precision bearings. Therefore, pitting is a common failure mode of precision rolling bearings. Let’s now explore the impact of fatigue pitting on the troubleshooting of precision bearings! Methods to Extend the Service Life of Precision Bearings:
The service life of precision bearings is closely related to production, manufacturing, and installation practices. Therefore, ensuring proper execution at every stage is essential to maintain optimal operating conditions and extend the service life of precision bearings.
1. Selection and Application of Dimensional Tolerances for Shafts and Bearing Housings: After the bearing is pressed into the housing, it should rotate smoothly without any binding. If rotation is noticeably difficult, the shaft is too large; please reduce the dimensional tolerance. If, after the precision bearing is pressed onto the shaft, there is a noticeable “looseness” during rotation, the shaft’s dimensional tolerance may be too large, or the shaft’s concentricity may be poor. Therefore, in controlling the dimensional tolerances of both the precision bearing and the bearing housing, ensuring proper concentricity is crucial. At this stage, many Chinese manufacturers focus only on dimensional tolerances and neglect concentricity.
2. Installation Method: Since precision bearings are high-precision products, improper installation can easily damage the bearing cross-section, thereby compromising the bearing. The installation of precision bearings requires specialized mounting shells; they must not be struck arbitrarily. When pressing onto the shaft, apply force only to the small diameter; when pressing onto the large diameter, apply force only to the large diameter. When installing using a pneumatic or hydraulic press, if the bearing is not centered during the outward pressing process, the bearing’s cross-section may be damaged, and the bearing’s raceways may be compromised.
3. Preventing Contamination: When mounting bearings on a moto
r rotor to achieve dynamic balancing, metal shavings generated during the balancing process can easily enter the bearings. Therefore, ensure the rotor is properly balanced before installing the bearings. Some manufacturers apply oil or vegetable oil to the bearing housing to facilitate installation and improve lubrication. However, it is difficult for operators to control the amount of oil or vegetable oil in the bearing housing. If there is an excessive amount of oil or vegetable oil, it may adhere to the bearing as the shaft rotates. Do not apply oil or vegetable oil to the bearing housing. If application is necessary, ensure that no oil or vegetable oil accumulates in the bearing housing during operation.
4. Prevention of Paint Rust: Paint rust typically occurs in sealed motors. Although the motor operates quietly during installation, after being stored in a warehouse for some time, the noise level of the motor becomes very loud. Upon disassembly, the bearings are found to be severely rusted. In the past, many manufacturers attributed this to a problem with the precision bearings.