Industrial shaft seals

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Industrial
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shaft seals
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Sealing lip materials
The sealing lips of SKF seals are generally
made of elastomer materials. However,
thermoplastic materials such as PTFE are
gaining in importance. Thermoplastics are
mainly used for special seals intended for
particular applications where there are
demands for high thermal or chemical
resistance.
SKF seals are generally produced from the
materials listed in Table 1. These materials
have characteristic properties making them
particularly suitable for specific applications;
these characteristics are briefly described in
the following. By changing the actual
formulation and blending it is possible to
modify the following properties:
N resistance to swelling,
N elasticity,
N chemical resistance,
N thermal resistance,
N behaviour in the cold, and/or
N gas permeability
of the elastomers to suit individual
requirements. Details regarding the chemical
resistance of the sealing lip materials to the
various media encountered in operation will
be found in the section “Chemical resistance”.
A code is used to identify the material of the
sealing lip of SKF seals, see Table 1. The codes
also appear in the designations of the metric
radial shaft seals. For seals where a combination
of materials is used, a combination of
the code letters is used, e.g. RD.
Table 1. SKF Sealing lip materials
Composition of basic material
Designation
according to SKF IS01629 ASTM 1) D1418
IS01043.1,
ASTM D1600
DIN 7728 Part 1
Acrylonitrile-butadiene rubber (nitrile rubber) R NBR NBR
Hydrogenated acrylonitrile-butadiene rubber H WNBR NEM
(Duratemp ® )
Carboxylated nitrile rubber (Duralip ® ) D X-NBR X-NBR
Polyacrylate elastomer P ACM ACM
Silicone rubber S MVQ VMQ
Fluoro rubber V FPM FKM
Polytetrafluoro-ethylene T PTFE PTFE
Leather L – –
Felt F – –
1) American Society for Testing and Materials
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