Barden Developer And Manufacturer Of Standard And Specialised Bearing Cages

In any application involving rolling element bearings, proper attention to bearing cage design and materials selection is essential to ensure reliable and long-term bearing performance. The role of ball bearing cages, or separators as they are sometimes known, is threefold. Firstly, they space the rolling elements equally apart and help with lubricant distribution within the bearing. Secondly, by separating the elements, they halve their running contact speed, thus allowing higher bearing speeds. Finally, they facilitate handling and installation of separable type bearings.

Since they are required to accelerate rapidly, bearing cages should be lightweight and be manufactured from materials that have superior strength/weight ratios. In the past, bearing cages were made from brass or bronze. These had good wear characteristics but progressively became too expensive for all but critical applications. This resulted in the development of steel bearing cages, which still provide excellent service - but at lower cost - particularly in ball bearings where the cage presents a large contact area to the balls. Steel bearing cages are now used widely, but continuing downward cost pressures mean that in some price sensitive applications cages manufactured from high performance plastics are preferred. However, bearings with steel cages are still favoured in applications where arduous environmental conditions prevail, or where the bearings are subjected to very high levels of vibration or extremes of heat.

While cost is always a factor with bearing cages many others enter into cage design and cage selection, including:

Low coefficient of friction with ball and race materials
Compatible expansion rate with ball/ring materials
Low tendency to gall or wear
The ability to absorb lubricant
Dimensional and thermal stability
Suitable density
Adequate tensile strength
Creep resistance

Where the operating conditions mean that standard cages are acceptable (see Fig 1) the choice for the designer is wide, particularly in respect of deep groove ball bearings. In Barden's range the principal bearing cage designs are side entrance snap-in types (Crown [general purpose], TA [high speed, general purpose], TAT [moderate to high speed, general purpose] TMT [moderate speed, general purpose] and symmetrical types (Ribbon [general purpose] W [general purpose, low torque], T). Both the Crown and Ribbon types are used at moderate speeds and are particularly suited for ball bearings, which are grease lubricated and equipped with seals or shields. The W-type is a low-torque pressed metal cage developed by Barden, and is available in many instrument sizes. It is loosely clinched to prevent cage windup (a torque increasing drawback of some cage designs) in sensitive low-torque applications. For higher speeds, with smaller bearing sizes, Barden offers the one-piece phenolic snap-in TA-type, and the two-piece riveted phenolic, aluminum-reinforced T cage for larger sizes. The aluminum reinforcement, another Barden first, provides additional strength, allowing this high-speed cage to be used in most standard width sealed or shielded bearings.

Angular Contact Bearing Cages

Phenolic is also the cage material used by Barden in its miniature and instrument angular contact bearings. The bearing cages are machined (B and H) types with high-speed capability. A feature of these cages is their outer ring land guiding, which allows lubricant access to the most desired point - the inner ring/ball contact area.

H-type phenolic cages are one-piece units with a through pocket halo design. They are suitable for high-speed general-purpose applications. The B-type cage is also intended for high-speed, general- purpose applications, but in separable bearings. The design of this cage includes ball pockets, which hold the balls in the outer ring when the inner ring is removed.

For high temperature applications, the cages of Barden's larger spindle and turbine angular contact bearings are machined from bronze or steel - the latter silver-plated. Most of these designs are also outer ring land guided for optimum bearing lubricant access and maximum speed capability.

Non Standard Cages For Specialised Applications

In cases where a standard cage does not meet the end user requirements, Barden's Product Engineering Department can help. Barden has developed and manufactured many specialised bearing cages for unusual applications. These employ materials as diverse as silver-plated steel, bronze alloys and porous materials such as sintered nylon or polyimide, which can be impregnated with oil to provide reservoirs for extended operational life.

About The Author:

Mark Harris is a successful author and regular contributor to http://www.bearing-n-bearings.com. A one-stop resource for the bearing industry featuring articles, comparisons and reviews of bearing related products and manufacturers.