What are ABEC ratings?
In the United States, the American Bearing Manufacturers Association (ABMA) maintains the standards deemed necessary by its bearing industry member companies. This includes revising existing, or proposing and preparing new standards.
These standards are then proposed to the American National Standards Institute (ANSI) for approval as US national standards. ANSI has a committee consisting of representatives from user organizations, manufacturers and the US government that are devoted to rolling bearing standards activities.
Tolerance classes for ball bearings were defined by a committee within the ABMA known as the “Annular Bearings Engineers Committee” (ABEC). These tolerances are commonly referred to as ABEC rating, or grade.
ABMA defines five classes: ABEC 1, ABEC 3, ABEC 5, ABEC 7 and ABEC 9. The higher the number of the classification, the tighter the tolerances become resulting in higher precision of the assembled bearing.
ABEC ratings and noise correlation
All bearings are extremely precise mechanisms, but a designer must consider the benefits of tighter tolerances in terms of performance and bearing life.
For example, there is a direct correlation with precision class and bearing life. Raceway parallelism, a feature controlled by ABEC, can impact bearing torque. A non-parallel raceway will result in torque spikes.
In high-speed applications, bearing runout can result in an imbalance in the rotating mass. These conditions can lead to premature failure and unpredictable life. Of course, the higher precision levels have the downside of higher cost.
While there may be a loose correlation between ABEC precision ratings and noise, higher ABEC ratings do not always mean a quieter bearing. ABEC ratings do not specify many other critical factors, such as smoothness of the rolling contact surfaces, ball precision and material quality all which may affect noise.
Another major factor affecting noise performance is the lubricant type. For very quiet running, the selection of a quiet grease is very important. Handling, installation and correct preloading will also ensure the quietest possible operation.
AST Bearings’ consultants and engineers are ready to provide further information about ABEC ratings, operating conditions/life and any other bearing questions you may have – contact them here.