by Christine Berlly
Ball bearing cages (AKA ball bearing retainers or ball separators) are components in ball bearings that separate the balls, maintain the symmetrical radial spacing and, in most cases, hold the bearings together.
Cages can provide lubrication by acting as a reservoir for oils or supplying a solid film via the cage material itself or a coating on the cage. The designer’s selection of the appropriate cage design is essential in achieving the desired life and performance of the bearing.
There are four basic types of cages that are the most common, readily available and will perform well in most applications: J-type, W-type, RJ-type, and TW-type.
“J” Type: Two piece ribbon consisting of two halves that are assembled one half from one side, and the other half from the opposite side. Fold down tabs secure the two halves. This type of cage is guided by the balls. “Loose” clinch type provides lower torque. Material is type 302 stainless steel. Brass and carbon steel are also available. These types of cages can operate at low to moderately high speeds. Loose crimp is standard. Tight crimp (JF) is used for higher speeds. Extra loose (JL) is used for low torque applications.
“W” Type: One piece steel crown. Mainly used in very small bearings. This type of cage is inner ring guided. Material is type 410 stainless steel. The cage snaps in from one side over the balls. It has excellent performance in low torque, low speed applications. Generally, the one piece steel crown is not used in high speed applications.
“RJ” Type: This type of cage is suitable for larger bearings (bore diameters over 10mm) with high load carrying capacities. It is a two piece ribbon consisting of two halves that are assembled one half from one side, and the other half from the opposite side. The two pieces are riveted together and are strong enough to with stand higher levels of vibration and acceleration. This type of cage is guided by the balls. Material is type 302 stainless steel or carbon steel sheet.
”TW” Type: Molded nylon cage. Reduces fluctuations in running torque and is suitable for high speeds. This type of cage is guided by the balls. The operating temperature range is from -30º C to +120º C. Also, available with a glass fiber reinforced nylon that is more rigid and capable of higher speeds.
AST Bearings’ consultants and engineers are ready to provide further information about ball bearing cages and any other bearing questions you may have – contact them here.