Tolerance classes and the corresponding values for certain tolerance characteristics are specified in ISO 492 (for radial bearings) and ISO 199 (for thrust bearings). In 2014 these standards were aligned with general ISO GPS (Geometrical Product Specification) standards such as ISO 1101 and ISO 5459. You can find more information on ISO 492 and ISO 199, and the changes that have been made to their previous editions, on the SKF e-learning platform.
There are three common tolerance classes for SKF ball and roller bearings:
|ISO tolerance class||SKF designation suffix||Description|
|Normal||–||Minimum standard for all SKF ball and roller bearings.|
|Class 6||P6||Tighter tolerances than Normal.
|Class 5||P5||Tighter tolerances than class 6.
The product sections for the various bearing types provide information on compliance with applicable tolerance classes. The tolerance class of a bearing cannot always be determined from its designation suffixes. Where the tolerance class is standard for the bearing, it is not specified in the designation suffixes.
For information about SKF bearings that have a tolerance class better than class 5, refer to Super-precision bearings.
Actual tolerance values are listed in the following tables.
Metric radial bearings, except tapered roller bearings:
Normal tolerances → table 1
P6 class tolerances → table 2
P5 class tolerances → table 3
Metric tapered roller bearings:
Normal and CL7C class tolerances → table 4
CLN class tolerances → table 5
P5 class tolerances → table 6
Inch radial bearings, except tapered roller bearings:
Normal tolerances → table 7
Inch tapered roller bearings:
Normal, CL2, CL3 and CL0 class tolerances → table 8
Normal, P6 and P5 class tolerances → table 9
Tapered bore, taper 1:12:
Normal, P6 and P5 class tolerances → table 10
Tapered bore, taper 1:30:
Normal tolerances → table 11
Where standardized, the values are in accordance with ISO 492, ISO 199 and ANSI/ABMA Std. 19.2.
The tolerance symbols that we use are in line with ISO 492 and ISO 199 and are explained in the previously mentioned tolerance tables and in table 12. The symbols normally refer to dimensional tolerances, only Kia, Kea, Sd, SD, Sia and Sea refer to geometrical tolerances.