The life of a rolling bearing is defined by the number of revolutions (or hours of operation at a certain speed): the bearing within this life shall have initial fatigue damage (spalling or defect) on any bearing ring or rolling element. However, no matter in the laboratory test or in the actual use, it can be clearly seen that under the same working conditions, the actual life of the bearing with the same appearance is greatly different. In addition, there are several different definitions of bearing "life", one of which is the so-called "working life", which means that the actual life of a bearing before damage is caused by wear and damage, which is usually not caused by fatigue, but by wear, corrosion, seal damage and other causes.
In order to determine the standard of bearing life, the bearing life and reliability are linked.
Due to the difference of manufacturing accuracy and material uniformity, even if the same batch of bearings of the same material and size are used under the same working conditions, their service life is not the same. If the statistical life is 1 unit, the longest relative life is 4 units, the shortest is 0.1-0.2 units, and the ratio of the longest to the shortest life is 20-40 times. 90% of the bearings do not produce pitting corrosion, and the number of revolutions or hours experienced is called the rated life of the bearing .
Rated dynamic load
In order to compare the bearing capacity against pitting corrosion, the maximum load that the bearing can bear when its rated life is one million revolutions (106) is the basic rated dynamic load, expressed in C.
In other words, under the rated dynamic load C, the reliability of the bearing working for one million revolutions (106) without pitting failure is 90%. The greater C is, the higher the bearing capacity is.
For basic dynamic load rating
1. Radial bearing refers to pure radial load
2. Thrust ball bearing refers to pure axial load
3. Radial thrust bearing refers to the radial component that produces pure radial displacement