1. Bearing seal overview
This question, put another way, asks: How is the inherent pollution protection of a bearing achieved? Since the question doesn't specify which type of bearing, my answer will cover most scenarios.
Not all bearings have inherent pollution protection. Most bearings operate within a bearing housing, and therefore the bearing housing environment defines the bearing's working environment. Protection against pollution is provided by sealing the bearing housing.
The design of bearing seal structures with sealing components varies between different brands. Specific project details and pros and cons depend on the specific structure; consult the corresponding supplier for more information.
However, generally, bearings with sealing components have good protective capabilities due to the contact (which can be light or heavy) between the sealing lip and the sealed surface, providing a certain level of prevention of liquid contamination.
But at the same time, friction between the edge and the sealed surface can generate additional heat. A balance between seal friction heat and seal effectiveness must be considered when choosing a type.
The nitrile rubber used as a sealing material also has a specific range of wear resistance. The maximum linear velocity tolerated by the lip surface is generally 15 m/s. For higher relative rotation speeds, more wear-resistant sealing materials are required.
The general operating temperature range for nitrile rubber is -30°C to 120°C, covering most industrial applications. The exact temperature range may vary slightly depending on the formula; Bearing users can provide specific values to the supplier.
Below this temperature range, the material becomes hard and brittle, causing easy damage. Above this range, the material softens and chars, causing premature failure and damage.
