Ball Bearing Cages

By Author: Amit Singh
Total Articles: 6
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Ball Bearing

A ball bearing is a type of rolling-element bearing that uses balls to maintain the separation between the bearing races.

The purpose of a ball bearing is to reduce rotational friction and support radial and axial loads. It achieves this by using at least two races to contain the balls and transmit the loads through the balls. In most applications, one race is stationary and the other is attached to the rotating assembly (e.g., a hub or shaft). As one of the bearing races rotates it causes the balls to rotate as well. Because the balls are rolling they have a much lower coefficient of friction than if two flat surfaces were sliding against each other.

Ball bearings tend to have lower load capacity for their size than other kinds of rolling-element bearings due to the smaller contact area between the balls and races. However, they can tolerate some misalignment of the inner and outer races.

Ball bearing Cages:

Ball Bearing Cages , also referred to as the bearing retainer or the bearing separator, is used to separate ...
... and position the balls at equal intervals around the bearing raceways. Retainers are available in two standard types, according to the size and design of the bearing itself. The material used is 300 series stainless steel. We are the quality manufacturer of ball bearing race, ball bearing cage and other ball bearing components in India.

The Ball Bearing Cages (also known as a ball bearing retainer or ball separator – these are used interchangeably), is the component in a ball bearing, that separates the balls, maintains the balls symmetrical radial spacing, and, in most cases, holds the bearings together. Cages can also be utilized in providing lubrication by acting as a reservoir for oils, or by supplying a solid film via the cage material itself or a coating on the cage. The designer’s selection of the appropriate cage design for the application is essential in achieving the desired life and performance of the bearing.

Ball bearing cages are guided by one of the available surfaces between the inner and outer rings. There are inner land riding retainers where the retainer’s bore slides, or is guided by, the O.D. of the inner ring, Outer land riding retainers where the O.D. of the retainer slides, or is guided by, the bore of the outer ring, and ball riding retainers where the retainers touch neither ring and is totally guided by the balls.

Unfortunately, all cages due to their rubbing contact produce frictional forces that increase the starting and running torque in the bearing. As a result, cages are available in a variety of configurations and materials that enhance performance in torque sensitive applications, at higher speeds, or in extreme environments. Some designs are limited to use in certain types of bearings depending on the size and configuration of the bearing. However, there are four basic types of cages that are the most common, readily available, and will perform well in most applications, namely J-type, W-type, RJ-type, and TW-type. Each is described in detail below in addition to some of the other less commonly used ball bearing retainer types.

Special Materials for Ball Bearing Cages:

Phenolic Resin - Retainers are manufactured from linen and or paper based phenolic materials because of their ability to absorb oil lubricants. During bearing operation the lubricants are wicked or forced out of the retainers due to G-forces, which provides extra lubricant to the rolling and sliding elements. The phenolic materials are manufactured from linen or paper sheets that are coated with a phenyl formaldehyde resin which are rolled into tubes under high heat, tension, and pressure.

Phenolic tubes for ball bearing retainers should be formed with less tension and pressure than the tubes manufactured for structural end use. This is done to assure that the paper and linen fibers are not completely filled with the resin, leaving virgin paper or linen available to absorb and act as a reservoir for oil lubricants. The retainers are then machined from the tubes.

Vacuum Impregnation - Prior to assembly into the bearing, the retainers are meticulously cleaned and placed into a vacuum chamber along with a container of the oil lubricant. A hard vacuum is drawn and the chamber is heated to approximately 1,200°F. The vacuum and heat draws out any air and moisture from the retainers and degasses the oil. While maintaining a vacuum the retainers are covered with the degassed oil. The container is then introduced to atmospheric pressure, which forces the oil into the virgin paper or linen materials. The retainers are then assembled into bearings. Some customers will request that the bearings must be subjected to low centrifugal forces to remove excess surface oil.

Cages, or retainers, can also be manufactured from sacrificial solid lubricants: Ball bearing retainers manufactured from Teflon, PGM or Salox M are extremely expensive and are used only in very specialized expensive equipment. Normally they are used in hard vacuum and outer space type applications. Both PGM and Teflon retainers have been used extensively in slow speed torque sensitive applications such as flow meters.

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