The seal of bearing can be divided into self-sealing and external sealing. The so-called bearing with seal is the bearing itself made into a sealed performance device. Such as bearing with dust cover, sealing ring, etc. This seal occupies very little space, is easy to install and disassemble, and the cost is relatively low.

The so-called bearing external sealing performance device, is in the installation of the end cover and other internal manufacturing into a variety of performance sealing device.

The following main factors should be considered in the selection of bearing external seal:

1. Bearing lubricants and types (grease and lubricants);

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

3. The advantages of the bearing structure of the shaft allow Angle deviation;

4. Circumferential velocity of the sealing surface;

5. The working temperature of the bearing;

6. Manufacturing cost.

According to the bearing working condition and the working environment to the seal degree requirements, in the engineering design is often a comprehensive use of various seal forms, in order to achieve a better seal effect.