Minimum Load-Deep Groove Ball Bearings
In order to keep bearings working in a good condition, a minimum load must be imposed, particularly on bearings working at high speeds, high accelerations, or with the load direction changing frequently, because under these working conditions, inertial force of balls and cage and lubricant friction will have bad influence on the rotation of bearings, and detrimental sliding movement may be caused.
The min loading Fmin of deep groove ball bearing can be calculated by the following formula:
V — Viscosity of grease under working temperature
n — Rotating speed
dm — Mean bearing diameter，dm = 0.5(d+D),mm
Kr — Min loading constant, can be seen from the following sheet：
When bearings are started at low ambient temperatures or in a condition where the viscosity of lubricant is very high, a larger minimum load probably is required. Usually, the weight of bearing supporting parts plus the load on the bearing have been over the required minimum load. If the weight can not be up to the minimum load, then extra radial load must be imposed on this type of bearing in order to meet the requirement of minimum load. The requirement can be met through axial preloading with springs.