Bearing life and rated load

The number of revolutions or hours that a bearing experiences before pitting occurs under a certain load is called the bearing life.

The lifespan of rolling bearings is defined by the number of revolutions (or the number of hours worked at a certain speed): Within this lifespan, bearings should experience initial fatigue damage (peeling or defects) on any of their bearing rings or rolling elements. However, whether in laboratory experiments or practical use, it is evident that bearings with the same appearance under the same working conditions have significantly different actual lifespans. In addition, there are several different definitions of bearing "lifespan", one of which is the so-called "working lifespan", which indicates that the actual lifespan that a bearing can achieve before damage is caused by wear. Damage is usually not caused by fatigue, but by factors such as wear, corrosion, and seal damage.

To determine the standard for bearing life, link bearing life with reliability.

Due to differences in manufacturing accuracy and material uniformity, even the same batch of bearings of the same material and size, under the same working conditions, have different lifespans. If the statistical lifespan is 1 unit, the relative lifespan of * long is 4 units, the relative lifespan of * short is 0.1-0.2 units, and the ratio of * long to * short lifespan is 20-40 times. 90% of bearings do not produce pitting, and the number of revolutions or hours experienced is called the rated life of the bearing.

To compare the load-bearing capacity of bearings against pitting corrosion, it is specified that the maximum load that the bearing can withstand at a rated life of one million revolutions (106) is the basic rated dynamic load, denoted as C.

That is to say, under the rated dynamic load C, the reliability of this type of bearing working at one million revolutions (106) without pitting failure is 90%, and the larger the C, the higher the bearing capacity.

For basic rated dynamic load

1. Radial bearings refer to pure radial loads

2. Thrust ball bearings refer to pure axial loads

3. Radial thrust bearing refers to the radial component that produces pure radial displacement

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