SKF - Rolling Bearings

Materials for rolling bearings
Polyamide 46
Glass fibre reinforced polyamide 46 (PA46) is
the standard cage material for some small and
medium-size CARB toroidal roller bearings.
The permissible operating temperature is
15 °C (25 °F) higher than for glass fibre reinforced
PA66.
Polyetheretherketone
The use of the glass fibre reinforced polyetheretherketone
(PEEK) has become more
popular for demanding conditions regarding
high speeds, chemical resistance or high temperatures.
The exceptional properties of PEEK
provide a superior combination of strength
and flexibility, high operating temperature
range, high chemical and wear-resistance and
good processability. Due to these outstanding
features, PEEK cages are available as standard
for some ball and cylindrical roller bearings,
such as hybrid and/or super-precision
bearings. The material does not show signs of
ageing by temperature or oil additives up to
200 °C (390 °F). However, the maximum temperature
for high-speed use is limited to
150 °C (300 °F) as this is the softening temperature
of the polymer.
Phenolic resin
Lightweight, fabric reinforced phenolic resin
cages can withstand heavy inertial forces, but
are not able to accommodate high operating
temperatures. In most cases, these cages are
used as standard in super-precision angular
contact ball bearings.
Cages made of other materials
In addition to the materials described above,
SKF bearings for special applications may be
fitted with cages made of other engineered
polymers, light alloys or special cast iron. For
additional information about alternative cage
materials, contact the SKF application engineer
ing service.
Seal materials
Seals integrated in SKF bearings are typically
made of elastomers. The type of material can
depend on the series and size of the bearing as
well as the application requirements. SKF seals
are generally made of the materials listed
below.
Acrylonitrile-butadiene rubber
Acrylonitrile-butadiene rubber (NBR) is the
“universal” seal material. This copolymer,
manufactured from acrylonitrile and butadiene,
has good resistance to the following
media:
• most mineral oils and greases with a mineral
oil base
• normal fuels, such as petrol, diesel and light
heating oils
• animal and vegetable oils and fats
• hot water
It also can tolerate dry running of the lip for
short periods. The permissible operating tempera
ture range is –40 to +100 °C (–40 to
+210 °F). Temperatures up to 120 °C (250 °F)
can be tolerated for brief periods. At higher
temperatures, the material hardens.
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