The dimensional and running accuracy of rolling bearings has been standardized internationally. In addition to the Normal tolerances, the ISO standards also cover closer tolerances, such as:
tolerance class 6, which corresponds to SKF P6 tolerance class
- tolerance class 5, which corresponds to SKF P5 tolerance class
For special applications like machine tool spindles, SKF also manufactures bearings with higher accuracy. These include the P4, P4A, PA9A, SP and UP tolerance classes. For additional information refer to Super-precision bearings.
For tolerance information about each bearing type, refer to Tolerances in the relevant product section. Bearings with higher accuracy than Normal are typically identified by a designation suffix for the tolerance class.
The tolerance symbols and their definitions are provided in table 1.