Kato, T., Yamane, S., Kanzaki, G., Munekata, S. et al., "Low Friction Seal for Muddy Water with Textured Surface," SAE Int. J. Passeng. Cars - Mech. Syst. 5(1):639-646, 2012, doi:10.4271/2012-01-0809.
This paper describes that the effect of surface texture of sealing lip on lubrication and sealing performance examined experimentally on practical aspect. Hub seals of PAC type were used in this study. A test apparatus and operating procedure were shown. The seal which had texture on the lip had lower frictional torque than plain one. The effect of friction reduction with the textured surface preserved up to 15 cycles, which was equivalent to a travel distance of 30,000 km. The textured surface 10 μmRz with grease on the lip kept sealing performance up to -0.10 MPa in static and dynamic conditions. The endurance time of sealing of the textured surface was almost the same as that of the plain surface in seal endurance test with muddy water.