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

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. An experimental method that uses a combination of scanning electron microscopy, optical microscopy, and three-dimensional profilometry to characterize the microasperity patterns found on radial lip seals was presented. The elastomer is made from a base nitrile rubber. The seal is designed for use with oil similar in viscosity to that of SAE 20W-50. Thus, the test was conducted with SAE 20W-50 motor oil. The sealing zone width was in the range of 100 μm, while the experimental data returned a mean sealing zone width of 56 μm, although this would certainly vary between seal designs. The film thickness in lip seals was generally expected to be on the order of 1 μm. This is an abstract of a paper presented at the 59th STLE Annual Meeting (Toronto, Ontario, Canada 5/17-20/2004).