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Tolerances

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 classSKF designation suffixDescription
NormalMinimum standard for all SKF ball and roller bearings.
Class 6P6Tighter tolerances than Normal.
Class 5P5Tighter 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.

Tolerance values

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
  • Thrust bearings:
    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.

Tolerance symbols

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.

Diameter series identification

The bore and outside diameter variation tolerances tVdsp and tVDsp for metric radial bearings (table 1, table 2 and table 3) vary depending on the diameter series to which the bearing belongs. To determine the diameter series, refer to table 13.

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