The Lubricants Work of Adhesion - A Key to Sealing Performance
Rotary shaft lip type seals consist of three components: The elastomeric sealing ring, the shaft and the lubricant. The point of view of this work lies on the lubricant. The lubricants influence on the sealing performance is commonly explained with its viscosity. As it could be seen in test-rig runs: The viscosity-approach is only valid for lubricants with similar chemical composition. For lubricants with dissimilar chemical composition, interfacial phenomena have to be taken into account. Surface free energy of lubricant, shaft and elastomer as well as the solids work of adhesion were therefore determined. The work of adhesion between shaft and lubricant seems to be the main reason for the level of the seals pumping rate. The work of adhesion between elastomer and lubricant plays a role as well.