Dimensional accuracy of bearings
Certain structures require higher running accuracy and/or higher speeds such as machine tools. Standard bearings often cannot meet this requirement, because they have normal production tolerances that meet the tolerance class P0. Higher precision bearings, however, have dimensional and running accuracies that are ISO standardized. Higher accuracies are specified and an overview of tolerance classes can be found in the table below.
Intermediate tolerance classes also exist per manufacturer. The above classes mainly occur in ball and angular contact bearings and are also indicated as suffix such as 6212 P6.
An overview of the standards:
DIN = Deutsches Institut für Normung
ISO = International Organization for Standardization
AFBMA = Anti-Friction Bearing Manufacturers Association
ABEC = Annular Bearing Engineers Committee (part of AFBMA)