Cotton fabric reinforced phenolic resin is a lightweight material. Cages made of this material can withstand heavy inertial forces and operating temperatures up to 120 °C (250 °F). The material tends to absorb oil, assisting the lubrication of the cage / rolling element contact and providing a safety margin for run down, should there be an interruption of lubricant supply.
Cotton fabric reinforced phenolic resin is the standard cage material for most super-precision angular contact ball bearings.
Polyamide 66 (PA66), with or without glass fibre reinforcement, is characterized by a favourable combination of strength and elasticity. Due to its excellent sliding properties on lubricated steel surfaces and the superior finish of the contact surfaces, PA66 cages reduce friction, frictional heat and wear. PA66 can be used at operating temperatures up to 120 °C (250 °F
). However, some synthetic oils and greases with a synthetic oil base and lubricants containing EP additives, when used at high temperatures, can have a detrimental effect on PA66 cages. For information about the suitability of cages, refer to Cages
PA66 is the standard cage material for many super-precision cylindrical roller bearings and angular contact thrust ball bearings.
Polyamide 46 (PA46) has the same excellent material properties as those of PA66. Glass fibre reinforced PA46 has a higher permissible operating temperature than glass fibre reinforced PA66 and can therefore be used at operating temperatures up to 135 °C (275 °F). However, as with PA66, some synthetic oils and greases with a synthetic oil base and lubricants containing EP additives, when used at high temperatures, can have a detrimental effect on PA46 cages.
PA46 is the standard cage material for the SKF Silent Series angular contact ball bearings in the 719 .. D and 70 .. D series.
Glass or carbon fibre reinforced polyetheretherketone (PEEK) is popular for demanding applications where there are either high speeds or high temperatures or a need for chemical resistance. The maximum temperature for high-speed use is limited to 150 °C (300 °F
) as this is the softening temperature of the polymer. The material does not show signs of ageing by temperature or oil additives up to 200 °C (390 °F
PEEK is the standard cage material for some super-precision angular contact ball and for high-speed design cylindrical roller bearings.
Brass is unaffected by most common bearing lubricants, including synthetic oils and greases, and can be cleaned using normal organic solvents. Brass cages can be used at operating temperatures up to 250 °C (480 °F
Machined brass cages are used in a number of super-precision double row cylindrical roller bearings and double direction angular contact thrust ball bearings and are standard for large super-precision angular contact ball bearings (d ≥ 300 mm).
Other cage materials
In addition to the materials described above, SKF super-precision bearings for special applications can be fitted with cages made of other engineered polymers, light alloys or silver plated steel. For information about alternative cage materials, contact the SKF application engineering service.