Bearing seals can be divided into self-contained seals and external seals. The self-contained seal bearing is to manufacture the bearing itself into a device with sealing performance. Such as bearings with dust cover, sealing ring and so on. The sealing space is small, the installation and disassembly are convenient, and the cost is relatively low.

The bearing-inserted sealing performance device is a sealing device with various properties manufactured inside a mounting end cap or the like.

The choice of bearing seals should consider the following main factors:

1. Bearing lubricant and type (grease and lubricant);

2. The working environment of the bearing, the size of the occupied space;

3. The advantage of the support structure of the shaft allows angular deviation;

4. The circumferential speed of the sealing surface;

5. The working temperature of the bearing;

6. Manufacturing costs.

Bearings and seals are divided into two types: non-contact and contact. The description is as follows:

1) Non-contact seal

A non-contact seal is one in which the seal does not touch its relatively moving parts and has a suitable clearance. This form of seal, which generates almost no frictional heat during operation, is free of wear and is particularly suitable for high speed and high temperature applications. Non-contact seals are commonly used in various forms such as gap type, labyrinth and washer type, and are used in different occasions.

The gap of the non-contact seal is preferably as small as possible.

2) Contact seal

A contact seal is a seal in which the seal is in contact with its relatively moving parts and has no gaps. Since the seal is in direct contact with the fitting, the friction is large during work, and the heat generation is large, which is easy to cause poor lubrication, and the contact surface is easily worn, thereby causing a decrease in sealing effect and performance. Therefore, it is only suitable for medium and low speed working conditions. Contact seals are commonly used in the form of felt seals, cup seals, etc., and are used in different applications.

According to the working conditions of the bearing and the working environment, the sealing degree is often used in engineering design to achieve a better sealing effect.