The seal ring is a rubber ring, with or without metal core, which is inserted in a seat to create a protective barrier on a shaft or between elements with relative motion – or static – in order to prevent contamination from dust or external medium. They are also able to retain lubricants within the mechanism to be protected. They can be used for both rotary motion, between interposed components, and for traversing movements.
They are available with various shapes of cross sections and may have one or two lips, stiff reinforcements or pre-load springs. They may be made of a wide choice of materials and may have different running smoothness ratings, resistance to aggressive chemicals and stiffness.