ABEC scale
ABEC stands for Annular Bearing Engineering Commitee 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 , 9 and 11, with 11 being the best.. 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 3, 5, and 7.
Most applications only require 3 rating while some very high precision parts like machine spindles or mills will require 5, 7 in ultra high precision.
Bearings not conforming to at least ABEC 3 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, 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.