Super Precision and Spindle Bearings

Super precision and spindle bearings are high-precision bearings that are designed for use in machine-tool spindles and other precision applications. Most super precision bearings and spindle bearings carry a high quality-rating such as ABEC-7 or ABEC-9, and run coolly and smoothly at high speeds. Annular Bearing Engineers’ Committee (ABEC) ratings are used to define different accuracy and tolerance ranges for bearings. As a rule, the higher the ABEC number, the tighter the bearing tolerance. Quality ratings for super precision and spindle bearings are also available from the Anti-friction Bearing Manufacturers Association (AFBMA), the American National Standards Institute (ANSI), the International Organization for Standardization (ISO), Japanese Industrial Standards (JIS), and Deutsch Indusrite Norm.  

There are four main types of super precision and spindle bearings: angular-contact ball bearings, radial ball bearings, roller bearings, and thrust bearings. Angular-contact ball bearings are the most common type of spindle bearing. A contact angle between the races and the balls is formed when the bearing is in use. Radial or deep-groove bearings can take radial and axial loads to varying degrees, but are most often used when the primary load is in the radial direction. Radial bearings consist of an inner ring, an outer ring, balls and sometimes a cage to contain and separate the balls. Roller bearings are used in rotary applications to replace sliding movement with low-friction, rolling motion. Thrust ball bearings are designed for pure thrust-loads. These super precision and spindle bearings can handle little or no radial loads. The rolling element can be a ball, needle, or roller. 

Specifications for super precision and spindle bearings include bore size, outside diameter, and materials of construction. The bearing industry uses a standard numbering system for bearings with metric-diameter bores. If the bore is hexagonal, then the dimension is measured across the flats.  If the bore is tapered, the smaller diameter is specified. For bore sizes 04 and up, multiplying the size by 5 yields the bore diameter in millimeters (mm). For housed bearings, the outside diameter (OD) includes the housing. For flanged bearings, the OD excludes the flange. In terms of materials, most super precision and spindle bearings are made of stainless steel, plastic, or ceramics. Products that are plated with cadmium and chrome are also available.

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