As bearings rotate under load the components see material fatigue. The basic life formula, also know as the L10 life formula is used to calculate the number of revolutions before a failure occurs. Life can vary considerably, it is affected by many variables that the formulas cannot account for. The formulas are simply a guideline and should no be relied upon for critical applications.
| L10=(Cr/P)3 • 106 Revolutions | L10=Basic rating life Cr=Basic dynamic load rating(kgf) n=R.P.M. fn=Speed factor |
| L10h=500 • f3h fh=fn • (Cr/P), fh=(33.3/n)1/3 | L10h=Basic rating life in hours P=Equivalent load(kgf) fh=Life factor |
L=aCL • aCM (Cr/P)3
| Lubrication | CL | Bearing type | a CM |
|---|---|---|---|
| Oil or Grease | 1 | Hybrid | 4 |
| Full ceramic | 1 | ||
| Water | 0.02 | Hybrid | 0.1 |
| Full ceramic | 1 |
L= Basic rating life (90% reliability life), 106 revolutions
Cr= Basic dynamic load rating of steel bearing of same size, N
P: Dynamic equivalent load, N
aCL : Lubrication coefficient
aCM : Material coefficient