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GLOSSARY OF SEAL TERMS

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Bonded Seal:

Design feature of a type of radial lip seal. The heel of the sealing element is attached (Bonded) to the seal case by and adhesive during the molding operation.

Bore, Housing: (Bore, Seal)

A cylindrical surface which mates with the outside surface of the seal outer case.

Case, Inner: (Shell, Inner)

A rigid, cup-shaped component of a seal assembly, which is placed inside the outer seal case. It can function as: reinforcing member, shield, spring retainer, lip-clamping device.

Case, Outer: (Shell, Outer)

The outer, cup-shaped, rigid structure of the lip seal assembly. Acts as a protective cover for the head of the sealing element

Dynamic Seal:

A seal which has rotating, oscillating, or reciprocating motion acting upon it

Durometer:

An instrument which measures with an indentor point the hardness of rubber by penetration, without puncturing the surface of the rubber.

Elastomer:

An elastic rubber like substance, such as natural or synthetic rubber

F.P.M.:

Feet Per Minute; used as a measure of shaft speed instead of R.P.M. To convert R.P.M into F.P.M., use formula .262 x R.P.M. x diameter (inches) = F.P.M.

Fluid Side:

Side of the seal which in normal use faces toward the fluid being sealed.

Garter Spring:

Coiled wire spring with its ends connected. It is used for maintaining a sealing force between the sealing element and a sealing surface.

Machine Lead:

Spiral grooves similar to a screw thread on a shaft surface that can result from improper finishing process; may result in early leakage.

Primary Lip:

The flexible elastomeric component of a lip seal, which contacts the rotating surface.

RA:

The average of all peaks and valleys from the mean line within cut-off (.010” of .254mm). Ra does not describe the surface profile (texture) and two shafts with the same Ra value can have very different surface characteristic.

RPM:

Revolutions per minute.

Run-In:

The period of initial operation during which the seal-lip wear rate is greatest and the contact surface is developed.

Run-0ut:

That run-out to which the seal lip is subjected due to the outside diameter of the shaft not rotating in a true circle. Usually expressed as T.I.R. (Total Indicator Reading).

RZ (din):

Average peak to valley height

Scoring:

A type of wear in which is generally defined by the inside and outside lip surfaces and the spring groove

Seal, Heel Section:

The portion of the lip seal which is attached to the seal case.

Seal, Outside Diameter:

The external diameter of a lip seal assembly. Usually the outside diameter of the outer seal case.

Seal Width:

The over-all axial dimension of the lip-seal assembly. Normally the total width measurement of the outer seal case.

Sealing Element:

The normally flexible elastomeric component of a lip-seal assembly which rides against the shaft.

Secondary Lip:

A short, non-spring loaded lip, which is located at the outside seal face of a radial lip seal. Used to exclude contaminants.

Shaft Diameter:

The outside diameter of the shaft at the location where the seal is mounted.

Shaft Finish:

The relative roughness, usually expressed in micro inches, of the outside diameter of the shaft. The smaller the number, the smoother the finish.

Shaft Seal:

Generally considered to be a lip seal or an oil seal, but a broad definition could include and sealing device mounted on a shaft or sealing a shaft.

Sleeve, Wear:

A replaceable metal ring. Generally used in assemblies to eliminate expensive shaft replacement caused by grooving that may occur at the seal-shaft interface.

S.T.B.M

Shaft-to-Bore-Misalignment, the amount by which the shaft is off centre, with respect to the bore’s centre.