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 levels of protection:

1. Non-contact dust covers: These covers do not contact the inner ring, thus avoiding increased start-up or running torque. However, their sealing performance is limited, and they offer poor resistance to grease being flushed out.

2. Contact seals:

Contact seals, typically made from nitrile rubber, achieve a tight fit against the bearing inner ring, offering superior contamination resistance. However, it should be noted that these seals introduce additional friction torque, potentially impacting bearing operational 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.

Specialist Recommendations for Preventing Lubricant Washout

For optimal washout protection, the following measures are advisable:

1. Selecting Suitable Grease

Highly water-resistant grease: Resists water washout while maintaining lubrication properties

Food-grade grease: Suitable for food processing industries, withstands periodic steam cleaning or chemical washing

PFPE grease: Offers exceptional chemical resistance for demanding environments

3. Optimising 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. Installation of Protective Devices:

Fit external bearing guards to minimise direct impact.

Design drainage channels to prevent persistent water erosion of bearings.

4. Regular Maintenance Checks:

Periodically inspect seal wear.

Monitor grease condition for timely replenishment or replacement.

Through the integrated application of these methods, bearing erosion resistance can be significantly enhanced, service life extended, and stable equipment operation ensured.