The Functions and Limitations of Bearing Seals

Bearing dust covers and seals serve as a vital barrier to protect the grease inside the bearing; they effectively prevent external particles from entering whilst ensuring that the grease does not leak out.

However, different types of seals vary in their protective effectiveness:

1. Non-contact dust covers:

These dust covers do not come into contact with the inner ring, so they do not increase start-up or operating torque; however, their sealing performance is limited, and they are not very effective at preventing the flushing out of lubricant.

2. Contact seals:

Contact seals made from nitrile rubber make close contact with the bearing inner ring, providing superior protection against contamination. It should be noted, however, that these seals increase friction torque, which may affect the bearing’s operational efficiency; therefore, additional protective measures are required.

Intermediate solution: Non-contact seals

Non-contact seals represent a middle ground between dust caps and contact seals. They are also made from nitrile rubber but do not rub against the inner ring, so they do not affect torque or maximum speed. These seals offer better protection than metal shields and are suitable for most standard applications.

Expert advice on preventing lubricant washout

To achieve optimal protection against washout, the following measures are worth considering:

1. Select the appropriate grease

Highly water-resistant grease: effectively resists water washout whilst maintaining lubrication performance

Food-grade grease: suitable for the food processing industry, withstanding regular steam cleaning or chemical washing.

IPFPE grease: offers extremely high chemical resistance, suitable for harsh environments

3. Optimise the sealing system

In heavy-duty or highly contaminated environments, the use of double-lip contact seals is recommended. Install protective devices:

Fit protective covers over the bearings to reduce direct impact

Design drainage channels to prevent standing water from causing continuous scouring of the bearings

4. Regular maintenance checks:

Regularly inspect seals for wear

Monitor the condition of the grease and top up or replace it in a timely manner

By comprehensively applying these methods, the bearings’ resistance to scouring can be significantly improved, extending their service life and ensuring stable equipment operation. For high-speed, light-load applications, consider combining non-contact and contact seals.