Miniature Bearings and Instrument Bearings Information
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Miniature bearings and instrument bearings carry moderate radial and thrust loads at low operating torque while providing high performance in a small envelope design. These types of bearings are single row ball bearings available in up to 1 1/8” outer diameter (OD) sizes. Miniature bearings and instrument bearings are available in stainless steel for applications that require corrosion resistance and chrome for maximum fatigue life. Typically, these materials are typically heat-treated to achieve optimum hardness and dimensional stability. Stainless steel and chrome are both suitable for most applications of miniature bearings and instrument bearings.
General Selection Factors
Several factors must be considered for choosing miniature bearings and instrument bearings. These factors include the ring material, design, shields and seals, cage, Annual Bearing Engineering Committee (ABEC) grade, radial play, and lubricant. Miniature bearings and instrument bearings are available in open, sealed and shielded configurations. Seals and shields are used in miniature bearings and instrument bearings (specifically ball bearings) to retain lubricants and prevent particulate contamination from reaching critical surfaces. Seals are used where minimal light contact is offered. Seals for miniature bearings and instrument bearings provide deterrence to particulate contamination, but increase torque and limit operating speeds. Shields are used in most applications.
Considerations for miniature bearings and instrument bearings should include the compatibility of cage and shield type designs for appropriate clearance. The cage, which is also referred to as the retainer or separator, separates and positions balls at equal intervals around the bearing raceway. Proper selection of a bearing cage is critical for meeting the load, speed, and temperature requirements of the application of miniature bearings and instrument bearings.
Miniature bearings and instrument bearings are also available in both flanged and unflanged designs. Other options for miniature and instrument bearings include treatments for arduous and hostile environments (such as those with high vacuum), high precision to Internal Standard Operating Procedures (ISOP) 4A / ABEC 9 and above standards, and hybrid miniature and instrument bearings with ceramic balls. The design of miniature bearings and instrument bearings is critical for the load-carrying capability and maximum operating speed. These factors directly impact the bearing’s operating life. Various types of miniature bearings and instrument bearings have been designed to meet the operating parameters of various applications.
ABEC Selection Factors
Factors to consider when choosing an ABEC grade include radial and axial runout requirements, bore and OD fits, and audible noise level. Suppliers of miniature bearings and instrument bearings that offer these types of grades show the available selection of bore and OD size tolerances, and the radial runout limits for each. ABEC Grades 3 and 7 are preferred for most standard applications. Typically, race finish and race geometry are superior in ABEC 5 and higher. These grades are generally recommended generally for precision assemblies where low noise, minimal runout, and long life are important considerations for miniature bearings and instrument bearings.
A-A-50602 - SELF-LUBRICATED BEARINGS
ABMA 20 - RADIAL BEARINGS OF BALL, CYLINDRICAL ROLLER AND SPHERICAL ROLLER TYPES - METRIC DESIGN
A-A-59643 - BEARINGS, BALL, ANNULAR, SINGLE ROW, RADIAL, NON-FILLING SLOT, MINIATURE SIZE, INSTRUMENT TYPE