Sealing surface – mating surface
The unstamped, hardened, and factory-ground faces of anti-friction bearings or appropriately machined shaft collars and ends, as well as support washers, thrust needle-bearing washers, or washers stamped from spring sheet, (or other economical solutions) are suitable as the sealing surface. Steel, brass, bronze, aluminum alloys, and ceramic can be used as the materials.
Properties of the sealing surface
The sealing surface must be perfectly smooth and hard and may not contain any spiral grooves or scratches. Surface hardness for steel, greater than HRC = 40, or less for other materials. Maximum surface roughness for use with oil Rt = 4 μm, or Rt = 10 μm for use with grease. The radial out-of-true of the sealing surface has no effect on the sealing properties, the permissible axial out-of-true can – referred to the permissible speed – be up to 0.05mm for use with grease or up to 0.03 mm for use with oil.
The reception holes of Types VI and DI should be fabricated in accordance with ISA H9 and the shaft diameter for Type VA in accordance with ISA H9. The reception hole and the shaft must be chamfered approx. 150 for at least 1 mm. The tolerances for the functional dimensions of the seals are as shown in the tables (pages Type VI, VA, DI).
In most cases “blind installation” is unavoidable, i.e. uniform seating of the sealing lip on the mating surface cannot be checked visually. Proper installation and assembly can be ensured if the axial shaft seal is inserted flat with the aid of an assembly sleeve or washer, so as to insure that the sealing lip cannot be damaged or distorted. Prior to inserting the seal, clean and lightly lubricate the sealing surface in order to keep wear to a minimum during the running-in-phase. The best seal is obtained when the prestressed sealing lip is located on the same plane as the end face of the seal, or does not protrude more than 0.1 mm. When using a mating washer, insure that the medium to be sealed cannot egress between washer and shaft. Seals should not be reused after having been removed, as removal usually deforms the seal or damages vital areas of it.
Until being installed, the axial shaft seal should be stored in a dry area and in the original packaging if possible. Under no circumstances may they be lined up on a wire ring or stored in a similar manner, as this could damage or deform the sensitive sealing lips. When staking axial shaft seals, care should be taken to ensure that they are stacked sealing lip to sealing lip or packing ring back-to-back. Improper handling of the axial shaft seal prior to installation can result in premature failure.