The ABEC scale 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). There are five classes from largest to smallest tolerances: 1, 3, 5, 7, and 9. There is no ABEC 11 standard despite the claims of some sellers. The higher ABEC classes provide better precision, efficiency, and greater speed capabilities, but do not necessarily allow the components to spin faster. The ABEC rating does not specify many other critical factors, such as smoothness of the rolling contact surfaces, ball precision or quality/type of steel used.
The bearing material is not specified in the ABEC grades. Bearings not conforming to at least ABEC 1 can not be classified as precision bearings as their tolerances are too loose.
The scale is designed to allow a user to make an informed decision about the type of bearing they are purchasing. High rated bearings are intended for precision applications like aircraft instruments or surgical equipment. Lower grades are intended for the vast majority of applications such as vehicles, mechanical hobbies, Roller skates, skateboards, fishing reels and industrial machinery. High ABEC rated bearings allow optimal performance of critical applications requiring very high RPM and smooth operation.
|ABEC 3||class 6||P6|
|ABEC 5||class 5||P5|
|ABEC 7||class 4||P4|
|ABEC 9||class 2||P2|
Actual changes in run-out between different ABEC grades
There are a number of factors covered by the ABEC grades. One is the eccentricity (roundness) of the track in the inner ring, which determines run-out. The figures given below show the maximum eccentricity allowable.
- ABEC 1: 0.0075 mm (0.000295")
- ABEC 3: 0.0050 mm (0.000197")
- ABEC 5: 0.0035 mm (0.000138")
- ABEC 7: 0.0025 mm (0.000098")
- ABEC 9: 0.0012 mm (0.000047")
- ISO 492:2002 – Rolling bearings – Radial bearings – Tolerances. Iso.org (2011-08-23). Retrieved on 2012-08-12.
- Bearing Precision Comparison. Minibearings.com.au. Retrieved on 2012-08-12.