What is a cage and what is its function?

What is a cage and what is its function?

Cage, a bearing component that partially wraps all or part of the rolling elements and moves with them, is used to isolate the rolling elements, usually guiding 

them and holding them inside the bearing. The function of the holder:

Rolling bearings generate heat and wear due to sliding friction during operation, especially under high temperature operating conditions. The action of inertial 

centrifugal force intensifies friction, wear, and heat, and in severe cases, it can cause burns or fractures to the cage, resulting in the bearing not working properly. 

Therefore, the material required for the retaining frame must not only have a certain strength, but also have good thermal conductivity, low friction coefficient, 

good wear resistance, strong impact toughness, low density, and a linear expansion coefficient close to that of the rolling elements. In addition, stamping retainers 

need to withstand complex stamping deformations and require materials with good processability.

A cage (also known as a bearing cage or bearing retainer) refers to a bearing component that partially wraps all or part of the rolling elements and moves with 

them, used to isolate the rolling elements, usually guide them, and keep them inside the bearing. The main functions of the cage include:

Isolation rolling elements: The retaining frame partially wraps around the rolling elements to prevent direct contact between adjacent rolling elements, thereby 

reducing friction and heat generation.

Uniform distribution of rolling elements: The cage evenly distributes the rolling elements around the entire bearing, providing uniform load distribution, 

ensuring smooth bearing operation, low noise, and long service life.

Guiding rolling elements: Guiding rolling elements in the no-load area to improve the rolling conditions inside the bearing, prevent destructive sliding, and 

ensure stable operation of the bearing.

Protecting rolling elements: During installation or disassembly, the cage can maintain the position of the rolling elements to prevent them from falling off 

or being damaged.

The types of retaining frames include:

Stamping cage: usually made of thin steel plate or thin brass plate, it has the advantages of light weight and large space, and is suitable for high-speed 

applications.

Solid retainer: Made of brass, steel, light alloy, nylon, or fiber-reinforced phenolic resin, suitable for applications that require high strength and corrosion 

resistance.

The design and material selection of the cage have a significant impact on the performance and service life of the bearing. Reasonable selection of cage 

types can improve the overall performance and service life of the bearing.