For a single or double row cylindrical bearing, the following formula would be used to obtain the DN factor.
Where: Once the DN factor of a bearing has been obtained, it can be used to consult grease selection charts in order to determine the correct lubricant.
Viscosity must be matched to the needs of the bearing in order to obtain maximum efficiency, and to avoid lubricant runout due to overheating, which is a consequence of metal-on-metal contact, as well as the failure of grease to extract heat from the bearing system.
This phenomenon can be the cause of metal-on-metal contact, which causes rapid wear and necessitates early replacement.
Jauhari shows that degree of starvation is a function of relative lubricant layer thickness for given operating conditions.
Online calculators exist to determine DN factor and correct grease viscosity.