In order to facilitate the comparison with sliding bearings, the friction torque of rolling bearings can be calculated according to the bearing inner diameter from the following formula:
* * * * * * * * * * * * * * * *
M = uPd / 2
* * * * * * * * * * * * * * * *
Here,
M: friction moment, mn.m {kgf.mm}
U: friction coefficient, table 1
P: bearing load, N{KGF}
D: nominal bore of bearing, mm
The friction coefficient u is greatly affected by bearing type, bearing load, rotation speed, lubrication mode, etc. The reference value of friction coefficient during stable rotation under general conditions is shown in table 1.
For plain bearings, u=0.01-0.02, sometimes up to 0.1-0.2.
Table 1 friction coefficient u of various bearings
Bearing type friction coefficient u
Deep groove ball bearings 0.0010-0.0015
Angular contact ball bearings 0.0012-0.0020
Aligning ball bearing
Cylindrical roller bearing
Full loaded needle roller bearing 0.0025-0.0035
Needle roller bearing with cage 0.0020-0.0030
Tapered roller bearings 0.0017-0.0025
Aligning roller bearings 0.0020-0.0025
Thrust ball bearing 0.0010-0.0015
Thrust aligning roller bearing 0.0020-0.0025