What Is a Bearing Cage?
The bearing cage (also called retainer or separator) is the component that holds the rolling elements at equal intervals around the bearing, preventing them from touching each other during operation. Without a cage, adjacent rolling elements would rotate against each other, causing friction, heat, and rapid wear.
Cage Types
Pressed steel: Most common, economical, adequate for standard speeds. Machined brass: Superior for high speeds and high temperatures. Polyamide (PA66-GF25): Lightweight, low noise, self-lubricating. PEEK: Chemical-resistant, extreme-temperature applications. Cage failure is a common bearing failure mode -- see the Failure Analysis Guide.
Frequently Asked Questions
What materials are bearing cages made from?
Common cage materials include pressed steel (most economical), machined brass (high speed, high temperature), glass-fibre reinforced polyamide/nylon (lightweight, low noise), and PEEK (extreme temperatures and chemicals). The suffix in the bearing designation indicates cage type: e.g., M = brass, TN = polyamide.