639 Metric Size Miniature Ball Bearings have deep groove geometry for high speeds and supporting both radial and axial loads. These 639 Metric Size Miniature Ball Bearings are for use in applications that involve combined radial and axial loads and a need for high running accuracy at high rotational speeds. For instance, 639 is often used in motors, ATMs as well as Card Readers. In Food & Beverage Industry, 639 is also popular and belongs to 63 series bearing. More applications about 639 are as follows.

Typical applications include:

Motors，Flow Meters，Medical Instruments，Vacuum Pumps，Robotics Industry，Crossbow，Food & Beverage Industry，Automation & Industry，Anemometer，ATMs & Card Readers，Galvanometers，Gas Meters，Industrial Encoders，Industrial Meters，Optical Encoders，Plastic Card Printers，Surveillance Systems，Fuel controls，Gyros, synchros and servos，Cryogenic coolers，Pulmonary assist devices，Clocks，Instrumentation，Drones and model，Fishing reel.

General Selection Factors

Several factors must be considered for choosing miniature ball bearings. These factors include the ring material, design, shields and seals, cage, Annual Bearing Engineering Committee (ABEC) grade, radial play, and lubricant. Miniature bearings are available in open, sealed and shielded configurations. Seals and shields are used in miniature 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 provide deterrence to particulate contamination, but increase torque and limit operating speeds. Shields are used in most applications.