Industrial shaft seals

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Housing bore requirements, small diameter seals (SDS)
General
The following requirements are designed to
guarantee the requisite interference fit for the
seal, the necessary static sealing and proper
installation.
Tolerances
The bore diameter d 2 in the housing should be
machined to tolerance H8, see Table 15. The
circularity (out-of-round) should be 1 to 2
tolerance grades better than H8, depending on
the conditions.
Surface finish
The surface roughness (to ISO 4288–1985 or
DIN 4768–1990) of the housing bore should
be kept within the limits specified below. These
limits apply for radial shaft seals with an
elastomeric outside diameter, or a metal case
coated with Bore-Tite, as well as the HS seals
made of elastomer.
Housing bores for seals with steel shells
To ensure that the seal can be installed
without damaging it, the housing bore should
have a 5 to 10° lead-in chamfers. The
transition should be free from burrs and the
transition R between the seal seating and the
shoulder should be in accordance with the
recommendations in Table 15. The depth of
the housing bore t2 should be at least 0,3 mm
greater than the seal width. The cylindrical
section of the bore should have a width t1
which is at least 0,85 b.
Recesses in the housing shoulder, which
must be considered at the design stage,
considerably facilitate removal of a seal from
the housing bore, see fig a in Table 15.
R a 1,6 to 6,3 µm
R z 10 to 25 µm
R max 25 µm
For seals with a steel shell without Bore-Tite
or similar coating, the limits are
R a 0,8 to 3,2 µm
R z 6,3 to 10 µm
R max 10 µm
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