BRZB super-precision cylindrical roller bearings, crafted to SP tolerance class specifications, come standard with a C1 radial internal clearance.

Upon request, bearings can be provided with a specialized reduced radial clearance that is smaller than C1. This is particularly useful when minimal operating clearance or preload is needed post-installation.

For bearings in the SP tolerance class, especially those in the NNU 49 series, a radial internal clearance greater than C1 is also available. When placing an order, the desired clearance level should be specified using the following suffixes:

CC1: standard clearance for N and NN series

CC0: standard clearance for NNU series

CCG: special clearance upon request

To ensure the specified radial internal clearance, individual bearing rings are factory-matched, identified with the same number, and typically packaged together. Before mounting, it’s crucial to verify that the identification numbers on both rings match, as any discrepancy could adversely affect the radial internal clearance and the final assembly’s performance.

For optimal running accuracy and rigidity, these super-precision cylindrical roller bearings should maintain a minimum radial internal clearance or preload after being mounted. Bearings with a tapered bore are generally installed with preload.

The necessary operating clearance or preload is influenced by factors such as speed, load, lubrication, and the spindle/shaft system’s required stiffness. The geometric accuracy of the bearing seats is also a critical factor in achieving the desired clearance or preload. Additionally, operating temperature and its distribution within the bearing must be considered, as they can affect the operating clearance or preload.

The radial rigidity of a bearing is determined by its elastic deformation (deflection) under load and can be expressed as a load-to-deflection ratio. However, since this relationship is nonlinear, only approximate values can be offered. These guideline values are applicable to moderately preloaded bearings under static conditions and moderate loads.

For more precise radial rigidity calculations, advanced computational programs can be employed. For further details, consult BRZB application engineering service and refer to the section on Rigidity.