How to buy rolling bearings?

According to the role of the load on the bearing relative to the rotation of the collar, rolling bearing collar bearing three kinds of load: local load, cyclic load, swing load. Usually cyclic load (rotating load), swing load using tight fit; local load in addition to the use of special requirements, generally should not use tight fit. When the rolling bearing ring bearing dynamic load and is a heavy load, the inner and outer ring should be used with interference, but sometimes the outer ring can be a little loose, should be able to make axial movement in the bearing housing hole; when the bearing ring bearing swing load and the load is lighter, can be used than the tight fit a little loose fit.

Rolling Bearings
Load size

The amount of interference between bearing collar and shaft or shell hole depends on the size of the load, when the load is heavy, use a larger amount of interference with; when the load is lighter, use a smaller amount of interference with. General radial load P is less than 0.07C for light load, P is more than 0.07C and equal to or less than 0.15C for normal load, P is more than 0.15C for heavy load (C is the rated dynamic load of the bearing).

Operating temperature

Bearing in operation, the temperature of the collar is often higher than the temperature of the adjacent parts, therefore, the inner ring of the bearing may be loose with the shaft due to thermal expansion, the outer ring may affect the bearing in the shell hole axial play due to thermal expansion. Help to choose the fit, the temperature difference of the bearing device part, expansion and contraction should be taken into account, the temperature difference is large, choose the shaft and the inner ring with the interference amount should be larger.

Rotational accuracy

When the bearing has high rotational accuracy requirements, to eliminate elastic deformation and vibration effects, the clearance fit should be avoided.

Bearing shell hole structure and material

For the form of shell hole, with bearing outer ring fit should not use interference fit, also should not make the outer ring in the shell hole rotation. For installation in thin-walled shell hole, light metal shell hole or hollow shaft bearing, should be used than the thick-walled shell hole, cast iron shell hole or solid shaft tighter fit.

Easy installation and disassembly

For heavy machinery, bearings should be used with a loose fit. When a tight fit is required, separate type bearings, inner ring with tapered hole and bearing with tightening sleeve or withdrawal sleeve can be used.

Axial displacement of the bearing

In the fit, when a ring of the bearing is required to be able to move axially in operation, the outer ring of the bearing and the housing hole of the bearing should be used with a loose fit.

Choice of fit

The fit of the bearing with the shaft is based on the hole system, while the fit with the housing is based on the shaft system. The bearing and shaft fit is different from the tolerance fit system used in machine manufacturing. The tolerance zone of bearing inner diameter is mostly below zero money, therefore, under the condition of using the same fit, the fit of bearing inner diameter and shaft is closer than the usual fit. The tolerance zone of the bearing outer diameter and the tolerance zone of the shaft in the base shaft system are in the same below zero line, but their values are not the same as the general tolerance system.