SKF life modification factor aSKF

The factor aSKF represents the relationship between the fatigue load limit ratio (Pu/P), the lubrication condition (viscosity ratio κ) and the contamination level in the bearing (ηc). Values for the factor aSKF can be obtained from four diagrams, depending on bearing type, as a function of ηc (Pu/P) for SKF standard and SKF Explorer bearings and different values of the viscosity ratio κ:
The diagrams are drawn for typical values and safety factors of the type normally associated with fatigue load limits for other mechanical components. Considering the simplifications inherent of the SKF rating life equations, even if the operating conditions are accurately identified, it is not meaningful to use values of aSKF in excess of 50.

Calculating the life modification factor aSKF

SKF engineering programs like SKF Bearing Select can be used to calculate the factor aSKF. Furthermore, SKF has also developed sophisticated computer programs incorporating the SKF rating life equation directly at the rolling contact stress level, permitting other factors influencing bearing life, such as misalignment, shaft deflection and housing deformation to be taken into account (→ SKF calculation tools).
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