The ABEC scale is an industry accepted standard for the tolerances

Tolerance (engineering)

Engineering tolerance is the permissible limit or limits of variation in# a physical dimension,# a measured value or physical property of a material, manufactured object, system, or service,# other measured values ....

 of a ball bearing

Ball bearing

A ball bearing is a type of rolling-element bearing that uses balls to maintain the separation between the bearing races.The purpose of a ball bearing is to reduce rotational friction and support radial and axial loads. It achieves this by using at least two races to contain the balls and transmit...

. 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. The higher ABEC classes provide better precision

Accuracy and precision

In the fields of science, engineering, industry and statistics, the accuracy of a measurement system is the degree of closeness of measurements of a quantity to that quantity's actual value. The precision of a measurement system, also called reproducibility or repeatability, is the degree to which...

, efficiency

Energy conversion efficiency

Energy conversion efficiency is the ratio between the useful output of an energy conversion machine and the input, in energy terms. The useful output may be electric power, mechanical work, or heat.-Overview:...

, and greater speed capabilities, but do not necessarily make the components 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, skates

Roller skates

Roller skates are devices worn on the feet to enable the wearer to roll along on wheels. A first basic type of roller skate consists of a boot with four wheels with ball bearings, arranged in the same configuration as the wheels of a typical car.-History:...

, skateboards, fishing reels and industrial machinery. High ABEC rated bearings allow optimal performance of critical applications requiring very high RPM and smooth operation.

ISO's equivalent standard is ISO 492.

ABEC	ISO 492
ABEC 1	normal class 6X
ABEC 3	class 6
ABEC 5	class 5
ABEC 7	class 4
ABEC 9	class 2

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. The figures given below is the maximum eccentricity allowable.

ABEC 1: 0.0075mm (0.000295")

ABEC 3: 0.0050mm (0.000197")

ABEC 5: 0.0035mm (0.000138")

ABEC 7: 0.0025mm (0.000098")

ABEC 9: 0.0012mm (0.000047")