Imported bearing is by the inner, outer ring, rolling body (ball, roller or needle) and keeper four parts, in addition to keeper, the rest are composed of bearing steel. When the import bearing work, bearing inside, outer ring, bearing rolling body between the role of high frequency, variable stress.

Imported bearing working conditions are very complex. Load concentration in the rolling body of a very small area. Theoretically speaking, for the ball, the role in a point; and for the roller column is the role in a line, and rolling body and the contact area between the ring is also very small (is point / line contact). Therefore, the import bearing in the work, its rolling body and the surface of the ring unit area to bear a lot of pressure, generally up to 1500-5000N/mm2; import bearing rotation, but also to bear the role of centrifugal force, the force with the increase in speed and increase; rolling body and the ring between not only the existence of rolling, but also sliding, so in the rolling body and the ring between There is also friction. In the above several kinds of force under the combined action, in the collar or rolling body surface fatigue strength of the first part of the low fatigue crack, and then the formation of fatigue spalling, so that the import bearing broken failure. Imported bearing normal form of damage is contact fatigue damage, common and plastic deformation, indentation, wear, cracking, etc..

Although the life and reliability of imported bearings and bearing design, processing and manufacturing, lubrication conditions, installation, maintenance and other factors, but the high quality and reliability of bearing materials is the key. Rolling bearing parts to be in tension, compression, bending, shear, alternating and other complex stress state and high stress value under, high-speed and long time work. Therefore, the performance requirements for rolling bearings have:

 (1) high resistance to plastic deformation capacity;

 (2) high resistance to friction, wear performance;

 3）high rotational accuracy and dimensional accuracy

 4) good dimensional stability;

 5) long service life and high reliability;

     For imported bearings working under special conditions, there are special requirements, such as high temperature resistance, low temperature resistance, anti-corrosion performance and anti-magnetic performance, etc.