The Function and Limitations of Bearing Seals
Bearing dust covers and seals serve as vital barriers protecting the internal grease within bearings. They effectively prevent external particulates from entering while retaining the lubricant.
However, different seal types exhibit varying degrees of protective efficacy:
1. Non-contact dust covers:
These covers do not contact the inner ring, thus avoiding increased start-up or operational torque. However, their sealing performance is limited, proving less effective at preventing lubricant washout.
2. Contact seals:
Contact seals, typically manufactured from nitrile rubber, achieve close contact with the bearing inner ring, offering superior contamination resistance. It should be noted, however, that such seals introduce friction torque, potentially affecting bearing efficiency, thus requiring supplementary protective measures.
Intermediate Solution: Non-Contact Seals
Non-contact seals represent a compromise between dust covers and contact seals. Also manufactured from nitrile rubber, they do not rub against the inner ring, thus having no impact on torque or maximum speed. These seals offer superior protection compared to metal shields and are suitable for most standard applications.
Expert Recommendations for Preventing Lubricant Washout
For optimal washout protection, consider the following measures:
1. Selecting Suitable Grease
Highly water-resistant grease: Effectively resists water washout while maintaining lubrication performance
Food-grade grease: Suitable for food processing industries, withstanding periodic steam cleaning or chemical washing.
IPFPE grease: Exhibits exceptional chemical resistance for demanding environments
2. Optimise the sealing system
For high-speed, light-load applications, consider combining non-contact and contact seals
In heavy-load or highly contaminated environments, dual-lip contact seals are recommended
3. Install protective devices:
Fit external bearing shields to reduce direct impact
Design drainage channels to prevent persistent flushing of the bearing by accumulated water