The main purpose of bearing cage is to separate the rolling elements to reduce the friction heat generated by the bearing and evenly separate the rolling elements to optimize the load distribution. Guide the rolling element in the no-load area of the bearing. For the separated bearing, the rolling element can be kept as a whole when installing or removing one of the bearing rings.

The cage centered on the rolling element allows lubricant to enter the bearing easily. The cage centered on the ferrule brings higher guidance accuracy. It is usually used for bearings that must withstand the high-speed, high vibration or inertial force generated by the overall movement of the bearing.

The main cage types are:

Stamped metal cages (steel or brass sheet) are lightweight and can withstand high temperatures.

The machined metal cage is made of brass, steel or light alloy. It can withstand high speed, high temperature, high acceleration and high vibration.

The polymeric material cage is made of polyamide 66 (PA66), polyamide 46 (PA46), polyether ether ketone (PEEK) or other polymeric materials. Polymer material cages have good sliding properties and almost no friction, so they can allow high speed. In case of poor lubrication, these cages can reduce the risk of sudden failure and side effects of failure, because they can work under limited lubrication conditions for a period of time.

Steel strut type cage is a pin through roller with perforation, and is only used for large-size roller bearings. This cage is relatively light and can accommodate a large number of rollers.