The origin of the ABEC scale
The ABEC rating is an industry-accepted standard for the tolerances of a ball bearing. It was developed by the Annular Bearing Engineering Committee (ABEC) of the American Bearing Manufacturers Association (ABMA).
The ABEC scale is designed to provide bearing manufacturers dimensional specifications that meet the standards of precision bearings in a specified class. Manufacturers who produce equipment that requires bearings must also know the dimensional tolerances to design parts that will accommodate a bearing.
The ABEC grade has become the recognized industry standard for tolerating all ball bearings and roller bearings. Therefore, bearing manufacturers all over the world must conduct ABEC grade assessments on their products. After evaluation, the ratings are etched onto the bearing. Bearing tolerances are also specified by the equivalent ISO 492 and JIS B 1514 standards.