Tribology_Index
Coefficient of Friction

Rolling Bearing Friction

More Details on rolling bearing friction are available on the links below

Rolling Bearing Friction

Rolling bearings are called anti-friction bearing.    They have high loading capacity and exhibit very low rolling friction torques.   The friction torques are similar or lower than ideally designed plain bearing operating under conditions of thick film lubrication.  Rolling bearing have low starting torques

The coefficient of friction in rolling bearings relates to the type of bearing, the speed of rotation, the load, the amount and viscosity of the lubrication, the friction of the seals, etc etc.

The bearing friction torque Mr = F . f . (d/2)

alternatively ..

The bearing friction torque Mr = F . fm . (Dm/2)

(friction values below marked with ***)

 Mr = Friction torque (Nmm) F = Radial (or axial load) (N) f = coefficient of friction of rolling bearing . fm = coefficient of friction of rolling bearing based on mean diameter d = Diameter of the bore of the bearing (Shaft diameter)(mm) D = Outside diameter of the bearing (mm) Dm = (d+D)/2 (mm)

These values relate to running bearings without seals and with optimimum lubrication..
The start-up friction values will be higher -up to twice the values quoted below..

 Single row ball bearing (radial Load) ..f = 0,0015 Angular contact ball bearing (single row) ..f = 0,0020 Angular contact ball bearing (double row) ..f = 0,0024 Self aligning ball bearing (radial load) ..f = 0,0010 Cylindrical roller bearings with cage ..f = 0,0011 Cylindrical roller bearings full complement ..f = 0,0020 Thrust ball bearing (axial load) ..f = 0,0013 Spherical roller bearing (radial Load) ..f = 0,0018 Taper roller bearings ..f = 0,0018 Needle roller bearings-with cage ..fm = 0,003 Needle roller ball bearings-full Complement ..fm = 0,005 Combined needle roller bearings ..fm = 0,004 Axial Needle roller ball bearings ..fm = 0,0035 Axial Cylindrical roller bearings ..fm = 0,0035

The seal friction should also be included if seals are fitted.   A reasonable average value for a first estimate would be 0.001.

More accurate values for bearing rolling friction are found in the suppliers technical literature..(see links below)

 Links to Rolling Bearing Information INA bearings..Rolling Bearing SKF..Ball Bearings

Tribology_Index
Coefficient of Friction