Industrial seal self study guide - SKF.com

Installation (cont.)
For best results, the center of the tool should be open so pressure is
applied only at the outer edge.
The tools used to install seals can often affect seal performance.
For instance, a screwdriver may easily cut the seal lip, but make
the damage invisible to the eye. Even blunt-end drifts can damage
the seal case or distort the seal from its proper working position.
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The arbor press installation method
provides the uniform pressure needed
to overcome seal .D. press fit (fig. 8b).
When using the wooden block
installation method, apply force
in the area over the center of
the seal (fig. 8c).
Ideal Installation Conditions—Arbor Press
This hydraulic press method is best for providing the uniform pressure
necessary to overcome seal O.D. press fit, usually 0.004 to 0.008
inches (0. 102mm to 0.203mm) larger than the bore (fig. 8b).
Before installation, pre-lube the seal. To protect the seal outer shell,
apply pressure through an installation collar that contacts the seal near
the O.D. and has a relieved center to avoid pressure on the I.D. of the
seal face.
When installing the seal in a step bore, be careful not to squeeze or
crush the seal case. When installing in a “through” bore, apply pressure
through a steel plate or plug larger than bore diameter (to set the seal
perpendicular to the shaft).
Alternative Installation
Method—Wooden Block Installation
Use of a wooden block as an installation tool is acceptable when the
seal is to be installed flush with a housing and no arbor press is available.
Before installation, pre-lube the seal. Use the flat surface of the woodblock
to press the seal in place. A steel hammer can be used to apply
force to the wood block and to overcome the seal’s press fit diameter.
Apply force evenly across the back of the seal. That is, avoid forcing
one side of the seal first, thus cocking the seal (fig. 8c). Apply no direct
force to the seal I.D.
Whatever tool is used, remember that seating force must be applied
and spread out around the entire circumference of the seal. A direct
blow on one side of the seal distorts the shell and can cause the lip
to be pressed against the shaft. This action produces increased
friction between the lip and the shaft surface.
If installation pressure is applied to the seal’s inside diameter, the shell
is forced upward, lifting the lip from the shaft surface. If the seal is
cocked—not perpendicular to the shaft and bore—the result will be
too much contact on one side, and not enough on the other.
Careless installation is one of the most common reasons for seal
problems. The end-user can prevent these problems by reviewing
and following the recommendations on the opposite page.