Industrial shaft seals

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be achieved by plunge grinding; whole number
ratios of the grinding wheel speed to the
workpiece speed should be avoided. The
grinding wheel should be dressed using a
cluster head dressing tool and the smallest
possible lateral feed, or a profile dressing roll
without lateral feed. The negative influence of
directionality in any particular case can only be
ascertained by test running under conditions of
alternating rotation.
The counterface should be free of any
damage such as bruises, scratches, cracks, rust
or raised sections. It is therefore important
that it be properly protected until final
mounting takes place. Such protection can, for
instance, be provided by threading a cardboard
tube over the counterface, or preferably over
the whole shaft.
Hardness and surface treatment
The surface hardness of the counterface
should normally be at least 55 HRC or 600 HV
and the hardened depth should be at least 0,3
mm. Under certain conditions, e.g. where
speeds are low, lubrication good and
contamination absent, counterfaces having a
lower hardness than 55 HRC may be suitable.
Surfaces which are nitrided, phosphated or
have a galvanised layer may also be suitable in
special cases, but this must be determined for
each specific case.
Table 13. Counterface tolerances for inch size seals
Shaft diameter Diameter tolerance (h11) Circularity tolerance (IT8)
Nominal Deviation Deviation
d 1
over incl. high low max
in in in
– 4 +0.003 –0.003 0.002
4 6 +0.004 –0.004 0.002
6 10 +0.005 –0.005 0.003
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