Retainers keep the balls evenly spaced around the raceway preventing ball to ball contact and allowing higher speeds. They also help to retain grease around the balls and raceways. For greater accuracy and to prevent additional friction, it is important that the retainer is not allowed too much radial movement. To achieve this, the retainer is guided by either the balls or one of the rings. See below for information on how each cage type is guided.

Metal Crown / Ribbon

Ball bearing crown retainerThese standard retainers are manufactured from carbon steel for chrome bearings and AISI304 or AISI420 grade stainless steel for stainless bearings. These were often made from brass which also offered a high temperature capability but this is much less common due to higher cost of brass and advances in steel technology.

Ball bearing ribbon retainerFor higher temperatures, stainless steel is usually recommended. The crown cage and ribbon cage perform the same function but the crown cage is used primarily on smaller miniature bearings and thin-section bearings where space is more limited. Steel cages are preferred for arduous operating conditions and where high levels of vibration are experienced.

  • Good for low to medium speeds
  • Can withstand higher temperatures according to the type of steel (see "Bearing Material" section)
  • Crown type - inner ring guided
  • Ribbon type - mainly ball guided

Reinforced Nylon Crown (TW)

Ball bearing nylon retainerThis moulded fibreglass-reinforced synthetic retainer has better sliding characteristics than the steel cage and produces fewer fluctuations in running torque. It can increase maximum speeds by up to 60 percent so is generally used in high speed applications and has good low noise properties. This retainer is not suitable for low temperature applications as it loses elasticity below about 30°C. In vacuum applications, it may become brittle.

  • High speed and low noise
  • Temperature range approx -30 to +120°C
  • Ball guided

Polyethylene Crown (PE)

Ball bearing phenolic retainerThis low speed retainer is used in 316 stainless steel bearings. It has very good corrosion resistance so can be used in the presence of seawater and many chemicals.

  • Very corrosion resistant
  • Temperature range -30 to +80°C 
  • Inner ring guided

PEEK Crown (PK)

Ball bearing phenolic retainerPEEK cages are often used in ceramic bearings, 316 stainless steel bearings and PEEK bearings. They are highly corrosion resistant, have a wide temperature range and are suitable for vacuum use.

  • Very corrosion resistant
  • Low outgassing so suitable for vacuum use
  • Temperature range -70 to +250°C 
  • Inner ring guided

PTFE Crown (PE)

Ball bearing phenolic retainerThis retainer is used in ceramic bearings, 316 stainless steel bearings and PTFE bearings. It is highly corrosion resistant and has a very wide temperature range.

  • Very corrosion resistant
  • Temperature range -190 to +200°C 
  • Inner ring guided

Nylon Crown (PE)

Ball bearing phenolic retainerThis is mainly used in our acetal plastic bearings. Unlike the TW cage, this is not a reinforced cage so not suitable for high speeds. It is corrosion resistant but may swell after a few months if constantly used in water or a continuously damp environment.

  • Corrosion resistant
  • Temperature range -30 to +100°C 
  • Inner ring guided

Full Complement (F/B)

Full complement bearingA full complement (or full ball) bearing contains extra balls and has no retainer. It is used for its greater radial load capacity although axial load capacity is very small. These bearings can only be used at low speeds and bearing torque is increased due to ball to ball friction. An exception is a hybrid full complement bearing (ceramic balls)  which can be used for higher speeds due to the lower friction coefficient of the ball material. Improved steel and hardening techniques have increased the load capacities of bearings with cages and the full complement bearing is much less common now.

  • Higher radial load capacity
  • Low speed only (except with ceramic balls)
  • Low axial load 
  • Increased bearing torque

Our determination to remain specialised gives us a high level of product knowledge, providing bearing and lubrication solutions to existing or potential customers, whether individuals or large corporations. We don’t just sell bearings, we help to solve your problems. - Chris Johnson, managing director of SMB Bearings.