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 are 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.

Typical Applications	Shaft Fit	Shaft Diameter	Housing Fit	Housing Diameter
Inner ring rotation	.0000 – .0004T	     d+.0000	.0000 – .00004L	D+.0002
(Inner ring press fit, outer ring loose fit)		    d+.0002		D+.0000
Outer ring rotation	.0000 – .0004L	     d+.0002	.0000 – .0004T	D-.0002
(Inner ring loose fit, outer ring press fit)		     d-.0004		D-.0004
Tape guide roller, pulley, cam	.0000 – .0004L	     d-.0002	.0001L – .0003T	D-.0001
follower, outer ring rotation		       d-.0004		D-.0003
Drive motor (spring preload)	.0001T – .0003L	      d-.0001	.0000 – .0004L	D+.0002
		     d-.0003		D-.0000
Precision synchro or servo	.0001T – .0003L **	     d-.0001	.0001T – .0003L **	D+.0001
		     d-.0003		D-.0001
Potentiometer	.0001T – .0003L	     d-.0001	.0000 – .0004L	D+.0002
		     d-.0003		D-.0000
Encoder spindle	.0001T – .0003L **	       d-.0001	.0001L – .0003T **	D-.0001
		      d-.0003		D-.0003
 * In inches	Example:	To use SSR-2 bearing in a potentiometer the shaft diameter should be .1250 .0001 to .1250 -.0003 or .1249 to .1247. The housing should be .3750 +.0002 to .3750 -.0000 or .3752 to .3750
 L = Loose Fit
 T = Tight Fit
 d = Bearing Bore as listed
 D = Bearing O.D. as listed
 ** Bearing must be purchased with bore and O.D. coding

The material of the shaft and housing should be taken into consideration. An aluminium housing will expand more than a steel housing so requires a greater interference fit than a steel housing. Greater interference fits are required in thin walled or plastic housings and also on hollow shafts.

The bearing installation has close relationships with the accuracy, life and performance. 　Therefore the design and assembly departments should fully research into the bearing installation.
It is better to implement installation according to the operation standard. The items of the operation standard are usually as follows:
1. Clean bearing and its related parts
2. Check the size and finishing conditions of the related parts
3. Installation
4. Examine bearings after installation
5. Feed the lubricant
The bearing packing should be opened shortly before installation. There is no need for cleaning to ordinary lubricating grease lubrication, direct-filling of lubricating grease or lubricating oil. Whereas it should use the clean oil to rinse the instrument purpose bearing or high speed purpose bearing etc. and get rid of the anti-rusting agent on the bearing. The bearing easily gets rusty without rust inhibitor. Therefore special care should be taken to such kind of the bearing.
What is more, the bearing which has been sealed with lubricating grease can be put into direct use with no cleaning at all.
The installation methods of the bearing vary according to the difference in the bearing structure, matching, condition. As it is mostly of axle rotation, the inner ring needs interference fit. The cylindrical bore bearing is commonly pressed in by pressing machine or most probably, it adopts the heat installation method. The taper hole can be directly
installed in the taper axle or by sleeving.
When it has been mounted to outer casing, usually it has excess clearance fit, the outer ring has shrink range, it will be pressed in

Interference fits can affect rotational accuracy by distorting bearing rings. The standards of roundness and surface finish which apply to the bearing should also apply to shaft and housing. This is very important for electric motor and other quiet-running applications. Miniature and thin-section bearings are particularly susceptible to distortion which leads to higher noise and vibration levels. If rotational accuracy is important, a combination of close bearing tolerances and close shaft/housing tolerances should be used to obtain the correct fit with the minimum interference.