Cookies on the SKF website

We use cookies to ensure that we give you the best experience on our websites and web applications. By continuing without changing your browser settings, we assume you give your consent to receive cookies. However, you can change your browser cookie setting at any time.

Kinematic replenishment/starvation reduction factor

For oil-air, oil jet, low level oil bath lubrication (i.e. oil level H lower than the centre of the lowest rolling element) and grease lubrication methods, continuous over-rolling displaces excess lubricant from the raceways. In applications where viscosity or speeds are high, the lubricant may not have sufficient time to replenish the raceways, causing a "kinematic starvation" effect. Kinematic starvation reduces the thickness of the hydrodynamic film (decreasing κ value, refer to Viscosity ratio κ) and rolling friction.
For the type of lubrication methods described above, the kinematic replenishment/starvation reduction factor can be estimated using

Φrs Kinematic replensihment-starvation reduction factor

φrs =kinematic replenishment/starvation reduction factor
e=base of natural logarithm 

Krs =replenishment/starvation constant: 

= 3 x 10-8 for low level oil bath and oil jet lubrication 

= 6 x 10-8 for grease and oil-air lubrication
Kz =bearing type related geometric constant (table 1)
ν =kinematic viscosity at operating temperature of the oil or the base oil viscosity of the grease [mm2/s]
=rotational speed [r/min]
=bearing bore diameter [mm]
=bearing outside diameter [mm]
SKF logo