RBC Thin Section Ball Bearings
Adjustment Factors for Rating Life
RBC thin section ball bearings are engineered to solve a variety of design problems that cannot be solved with conventional ball bearings.
General Information
ADJUSTMENT FACTORS FOR RATING LIFE
If a bearing design and operation deviates significantly from normal, it may be necessary to use additional factors to estimate the fatigue life Ln.
Ln = a1 * a2 * a3 * L10hrs
with  a1 = reliability factor
     a2 = material & processing factor
     a3 = application factor
Reliability Factor a1
Reliability is the percentage of a group of apparently identical ball bearings that is expected to attain or exceed a specified life. For an individual bearing it is the probability that the bearing will attain or exceed a specified life. Typical bearing lives are calculated for 90% reliability. The life adjustment factors for other reliability numbers are shown below.
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Material Factor a2
For standard bearings the material factor a2Â is equal to 1.00. Factor a2Â is determined by material processing, forming methods, heat treatment, and other manufacturing methods. Some commonly used material factors are listed below:
| Material, Condition | a2Â max |
| 52100, Air melt | 1.00 |
| 52100, Vacuum degassed | 1.50 |
| 52100, Air melt & TDC Plate | 2.00 |
| 52100, Vacuum melt, (CEVM) | 3.00 |
| 440C, Air melt | 1.00 |
| 440C, Vacuum melt (CEVM) | 2.00 |
| M50, Vacuum melt (CEVM) | 5.00 |
| M50, Vacuum re-melt (VIM-VAR) | 8.00 |
Application Factor a3
The application factor a3 is equal to 1.0 for most applications. Unusual or extreme conditions in certain applications such as low speed, shock loading, vibration, and extreme temperature may lower the application factor to 0.50. Contact your RBC Sales Engineer for help in determining this factor for your special application.
