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GRW High Precision Ball Bearings

High precision ball bearings in grades up to ABEC 9 with bores from 1 to 30mm and comparable inch dimensions


Inch/Metric Bearing
Desired Bore
Desired Outer Diameter

duplex bearings

Duplex bearings are two matched bearings which, depending on the requirements, provide the following characteristics:

  • Accurate bearing positioning in radial and axial directions, which can vary from defined clearance to controlled rigidity
  • Limitation of the system’s yield
  • High load capacity compared to single bearings

The matching of the bearings is achieved by loading each single bearing with the desired preload and then grinding the inner or outer rings until the surfaces of both rings are flush with each other.

Two of the bearings treated in this manner are assembled according to the instructions on the package and loaded axially until the ground faces meet, this repeats the preload previously set in manufacture. Depending on the matching used either the inner rings or the outer rings or possibly both are preloaded against each other. 

The ball bearings must be mounted according to the instructions on the packaging labels. If there are no special customer requirements, our ball bearings are paired with a preload of 5N and a nominal contact angle of 15o. In principle this can, however, be altered to suit the operating conditions and requirements. The preload should not, however, be set higher than necessary as it will unnecessarily increase the torque. This has a direct influence on the life of the ball bearing.

The radial clearance should be set higher than usual for Duplex bearings so that the contact angle, the rigidity and the axial loading become greater.

In order to achieve optimum fits Duplex bearings are always calibrated into two groups on the bore and outside diameter and supplied packaged with the same code. They should also, if possible, be fitted with calibrated shafts and housings (see ‘Calibration of Bore and Outside Diameter’). 

The ball bearing fits should therefore be selected carefully as an interference fit on the inner and outer ring would change the preload.    


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