The function of an axial face seal, like felt radial seals, is to protect bearings from contaminants. It functions on a rotating or stationary shaft, but not an oscillating one.

Rubber rotary-shaft axial face seals provide a contact seal to keep dirt, dust, and moisture from bearings and critical machine parts. A flexible lip is tolerant of angular misalignment, eccentricity, axial movement, yet produces lower friction than other contact-seal designs.

The rotary-shaft axial face seal can be used as a primary seal for grease and oil, and against water splash, dirt, and other contaminants. In addition, it can be used as an auxiliary dirt seal to protect other radial-lip seals.

One proprietary axial face seal is a one-piece ring of molded polymer. Slight undersizing of the seal ID allows it to constrict, holding it in place on the shaft. The sealing lip contacts the axial face to keep contaminants from protected machine parts. Up to about 1,600 fpm, no backup is required. From 1,600 to 2,400 fpm, a backup ring on the shaft is needed when the seal operates in the presence of lubricants. From 2,400 to 3,000 rpm, radial support is required to maintain constriction to the shaft. Above 3,000 fpm, centrifugal force may lift the finger away from the axial face. In this case, the seal should be mounted stationary so only the axial face rotates. Seal contact speeds are then possible to 20,000 fpm.