Sealing theory and hydrodynamic processes in the area of the sealing edge of radial shaft seals rings
The sealing effect of radial shaft seals rings is determined by the design and the material. Important design parameters include which springs are used, the angle on air and oil sides and the internal diameter of the sealing lip, the membrane length and thickness, the suspension of the lip, the effective spring distance, and much more. As far as the material is concerned, the leaktightness of the radial shaft seals ring is affected by the polymers, filler and other contents.
Generally, when designing a shaft seals ring, the oil-side angle has to be twice the air-side angle, the inclination of the spring must be towards the air side from an axial perspective, the sealing lip has to overlap the shaft, etc. The restoring forces resulting from the expansion of the sealing lip, which are divided between the spring and the rubber, ensure that the sealing lip presses radially against the shaft.
The resultant pressing force is distributed asymmetrically in the axial direction, and this is decisive for the leaktightness of the radial shaft seals ring.
KACO has developed a measuring method that can be used to precisely determine the pressing force distribution of radial shaft seals rings with both elastomer and PFTE sealing lips. This measurement provides detailed information about the correct design of the radial shaft seals ring in the area of the sealing edge.