Page 27 - Rollingbearings

Components and materials
Cages • Pin-type cages (ig. 19)
Steel pin-type cages need pierced rollers
The primary purposes of a cage are: and are only used together with large-
sized roller bearings. These cages have
• separating the rolling elements to reduce relatively low weight and enable a large
the frictional heat generated in the number of rollers to be incorporated.
bearing
• keeping the rolling elements evenly
spaced to optimize load distribution
• guiding the rolling elements in the
unloaded zone of the bearing
• retaining the rolling elements of separable
bearings when one bearing ring is Bearing basics
removed during mounting or dismounting

Cages are radially centred (ig. 15) either on: Fig. 15
Options for cage centring A.1
• the rolling elements
• the inner ring
• the outer ring

Cages centred on the rolling elements permit
the lubricant to enter the bearing easily. Ring
centred cages, which provide more precise
guidance, are typically used when bearings
must accommodate high speeds, high vibra-
tion levels or inertia forces stemming from
movements of the whole bearing.
The main cage types are:

• Stamped metal cages (ig. 16) Fig. 16 Fig. 17
Stamped metal cages (sheet steel or Stamped metal cage Machined metal cage
sometimes sheet brass) are lightweight
and withstand high temperatures.

• Machined metal cages (ig. 17)
Machined metal cages are made of brass
or sometimes steel or light alloy. They
permit high speeds, temperatures, accel-
erations and vibrations.

• Polymer cages (ig. 18)
Polymer cages are made of polyamide 66
(PA66), polyamide 46 (PA46) or some-
times polyetheretherketone (PEEK) or
other polymer materials. The good sliding Fig. 18 Fig. 19
properties of polymer cages produce little Polymer cage Pin-type cage
friction and, therefore, permit high speeds.
Under poor lubrication conditions, these
cages reduce the risk of seizure and sec-
ondary damage because they can operate
for some time with limited lubrication.

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