TLDR: The ABEC scale is a way to measure how precise a ball bearing is. It helps manufacturers make bearings that meet certain standards, and it also helps people choose the right bearing for their needs.
The ABEC scale was created by a group called the Annular Bearing Engineering Committee (ABEC) of the American Bearing Manufacturers Association (ABMA). They wanted to establish a standard for the tolerances of ball bearings, which are used in many different machines and equipment.
The ABEC scale has five classes, numbered 1, 3, 5, 7, and 9. The higher the number, the tighter the tolerance and the more precise the bearing. So, an ABEC 9 bearing is more precise than an ABEC 1 bearing.
The ABEC scale is not the only standard for measuring bearing precision. There is also an international standard called ISO 492, as well as standards in Germany and Japan. These standards have similar classifications to the ABEC scale.
It's important to note that the ABEC rating doesn't tell you everything about a bearing. It doesn't cover factors like load handling capabilities, ball precision, materials, hardness, polishing, noise, vibration, and lubrication. So, a lower-rated bearing that meets the ABEC 7 requirement could still perform better than a higher-rated bearing that only meets the ABEC 3 requirement.
In summary, the ABEC scale is a way to measure the precision of ball bearings. It helps manufacturers make bearings that meet certain standards, and it helps people choose the right bearing for their needs. However, it's not the only factor to consider when selecting a bearing.