Importance of correct fitting of bearings

A bearing can only perform to its full capacity when it is correctly fitted on the shaft and in the housing. Insufficient interference on fitting surfaces could cause bearing rings to creep in a circumferential direction. Once this happens, considerable wear occurs on the fitting surface and both shaft and housing can be damaged. Furthermore, abrasive particles may enter the bearing causing vibration, excessive heat and damage to raceways. It is therefore necessary to provide bearing rings under rotating load with an adequate interference fit to prevent creep. When using thin-type bearings under low load, the bearings should be fastened by a nut. Statically loaded bearings generally do not need to be fitted with an interference fit. Only when subject to a high degree of vibration do both inner and outer rings require fitting with an interference fit.

Characteristics of Load and Fitting
Rotating Ring	Load	Load Condition	Fitting
		Inner ring rotating load Outer ring static load	Interference fit for inner ring Clearance fit for outer ring
		Outer ring rotating load Inner ring static load	Clearance fit for inner ring Interference fit for outer ring
In case of fluctuating load direction or  unbalanced load	Rotating or static	Indeterminate load direction	Interference fit for inner and outer ring