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ABEC scale
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ABEC stands for Annular Bearing Engineering Committee of the AFBMA. ABEC tolerance classes
define tolerances for major dimensions of steel ball bearings. The ABEC scale of tolerance classes
includes 1, 3, 5, 7 and 9. Higher numbers indicate closer conformance to certain critical bearing
dimensions. Bearings manufactured within tighter tolerance ranges provide greater accuracy of
shaft rotation and contribute to higher speed capability. However, the ABEC rating does not
specify many other critical factors, including smoothness of the rolling contact surfaces, ball
precision, and material quality.

ABEC Ratings
Bearings are rated on the Annular Bearing of Engineering Council or ABEC scale. The higher the
ABEC number, the greater the manufactured precision of the bearing. There are no required
materials to meet the ABEC specifications. The bearings simply have to be made to a certain
precision. ABEC ratings are 1, 3, 5, 7, and 9, with 9 being the best.

Most applications only require 1 or 3 ratings while some very high precision parts like machine
spindles or mills will require 5, 7 or even 9 in ultra high precision.

Bearings not conforming to at least ABEC 1 or the comparable ISO P0 standards are not precision
bearings. ABEC and ISO precision gradings are used for bearings throughout the industry.

Purpose
The ABEC 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 (although some skateboard and inline
skaters will sometimes use high abec for higher performance), fishing reels and industrial
machinery. High ABEC rated bearings allow optimal performance of critical applications requiring
very high RPM and smooth operation. High ABEC rated bearings do not make equipment go faster
or smoother, they allow high precision equipment to operate at their optimum speed and
efficiency.

References
"Advanced Bearings for High-speed Machining"
Society of Manufacturing Engineers "Spindle Bearing Basics"
http://www.sme.org/cgi-bin/find-articles.pl?&00no0052&ME&20001107&PUBME-66.249.64.18&
SME&
http://www.engineersedge.com/bearing/ball_bearings_tolerances.htm
ABEC FAQ Page
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