Precision Bearings

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High precision bearings are utilized in applications where superior accuracy, reliability of operation, high running speeds, long life, rigidity and limiting of noise and vibration are critical. High precision bearings are utilized on machine tools, such as turning centers, milling, grinders, machining centers and to support ball screws. Other precision bearing applications include aircraft, medical equipment and robotics. The chart below details how bearings are rated and the corresponding precisions. There are two major precision bearing ratings organizations. ABEC, which stands for Annular Bearings Engineer Committee, which determines standards for the AFBMA, Anti-Friction Bearing Manufacturers association, and ISO or International Standards Organization.

These standards measure the precision of a bearing as it relates to the published dimensions in microns. The bore, outside diameter, width and rotating accuracy are all measured. The higher the ABEC rating is, the more precise the bearing is. The lower the ISO rating (with exception of 0) of a bearing, the more precise the bearing is. Standard bearings are typically manufactured somewhere between ABEC 1 (ISO 0) and ABEC 3 (ISO 6) tolerances and are suitable for the majority of applications, and capable of high speeds. Generally a bearing is considered high precision when it is manufactured to ABEC 5, 7 or 9 (ISO 5, 4, 2) tolerances, with ABEC 7 (ISO 4) being the most popular.

Higher precision bearings are available in ball bearings, angular contact ball bearing, ball screw support bearings, cylindrical roller bearings, spherical roller bearings and tapered roller bearings. The most common high precision bearing is the angular contact bearing, also referred to as a spindle bearing. This high precision bearing is commonly found on most machine tools, where accuracy, speed and rigidity are critical. While precision angular contacts are available for purchase as a single bearing, the majority of the time these bearings are sold in matched pairs to assure matching of bores. These bearings are also sold in triplex and quad sets. High precision bearings typically utilize either a bronze or phenolic ball cage instead of steel for reduced friction and increased speed. Pre-loading of the bearing is another feature of a high precision bearing, which ensures accuracy and rigidity. Typically, high performing greases or oils are utilized on precision bearings.

Bearing Service inventories common high precision “spindle” and ballscrew support bearings. Please contact Bearing Service to discuss the right high precision bearing for your application.