Thin Radial Ball Bearings

Thin radial ball bearings reduce rotational friction and support axial loads in both directions. They are used in applications with space and weight constraints, such as cameras and robotics.

Kaydon offers a number of options to optimize thin section bearing performance for your application. These include changes in radial play, lubricants and materials.

Ultra-Slim Design

The smallest NB Series thin-section deep-groove ball bearings help designers reduce equipment size and weight in robotic applications. They also feature low frictional torque to allow for precise rotation and lower moment loads. Combined with their compact size, these advantages result in significant space and cost savings.

Kaydon Reali-Slim ball bearings in this anthropomorphic robot swivel, tilt and rotate the arms, torso and head. The ceramic balls in these bearings require minimal lubrication and are less susceptible to aggressive cleaning liquids or corrosive contaminants.

The Reali-Slim bearings' primary cross sections remain the same as bore diameter increases, unlike standard radial ball bearings, which increase width and thickness proportionally. However, care must be taken with shaft and housing fits to avoid over-tightening of the inner and outer ring raceways, which can decrease internal clearance (radial play). The recommended radial fit, based on application loads, is shown in the Tolerance Tables. A good fit will prevent vibration, noise and abrasion in your application.

Precision

Unlike deep groove bearings that rely on seals to separate the balls and raceways, split thin section radial ball bearings have a gap between their inner and outer rings. This allows designers to set internal clearance (or preload) at the design stage, saving time and cost in assembly.

The design of the inner and outer ring races and the ball complement optimize the running accuracy of these bearings. They also have very low radial runout, and can support high speed and combined loads.

For applications where axial load capacity is important, a special version of this bearing type is available. This version is known as the A-Type and features a reduced shoulder on one side of either the inner or outer race ball path to accommodate axial thrust in one direction.

A basic dynamic radial load rating, C, for a bearing can be found in the ANSI/ABMA standard 9 and is calculated as the rated radial load at which 90% of the bearings in a group can still be serviced after 1 million revolutions. This rating may be impacted by operating conditions, lubrication and environmental factors.

Weight

Thin-section bearings help save space and reduce the overall weight of a design, dramatically decreasing friction and delivering excellent running accuracy. They are used in a wide range of applications including aerospace, semiconductor equipment and custom machinery.

An aluminum RBC thin section ball bearing designed to support an aircraft gun turret needed to take heavy radial and axial loads while maintaining low torque and good temperature compatibility. This was achieved by using a split inner ring and special balls that matched the coefficient of expansion of the aluminum, while providing multiple load carrying capabilities with very low torque.

Another example is an X-type, or 4-point contact, bearing that is ideal for moment loading. This is accomplished by using gothic arch raceways that create 4 contact points between the balls and raceways, as opposed to 2 contact points with the standard C-type bearing. The X-type also features a one-piece crown cage, which is typically machined from metal but can be injection molded.

Design Efficiency

Using thin section ball bearings in an automotive transmission reduced both the size and weight of the gear system. They were also used in a robotic arm that was designed to achieve both accuracy and simplicity of assembly.

The low friction of thin section radial ball bearings allows them to be used with smaller diameters than other sized radial bearings. This allows for greater precision and lower starting and running torques.

Shields and seals can be added to reduce the amount of dirt, dust and other contaminants that enter the bearing. This can increase the life of the bearing and improve its performance in harsh environments.

The fit of the inner and outer rings is crucial for the operation of thin section radial ball bearings. Too tight a radial fit will significantly reduce the internal clearance of the bearing, reducing the performance and speed ratings. Strictly following the recommended shaft and housing fits will ensure proper radial clamping and reduce frictional moments.