Surface characterization and experimental design for testing of a radial lip seal

In radial lip seals, it is generally accepted that sealing occurs through microasperities that form on the surface of the elastomer. It is most often thought that these asperities form during the first few hours of operation due to the stresses and wear in the seal. Thus, the formation of these asperities is highly dependent upon the specific operating conditions of the seal. This article studies the size, shape, and quantity of the asperities that are present on a specific seal design, when run at a certain set of operating conditions. From this analysis it has been determined that the hydrodynamic pumping aids that are present on the seal significantly affect the formation of microasperities. Radial lip seal samples affected by pumping aids had more distinct microasperities, but these asperities are clustered on the edges of the sealing zone, which is not the case for samples unaffected by pumping aids.