Oil Seals is usually called as Radial Shaft Lip Seals. In order to prevent the oil leaking from the distance of mechanical operation between friction parts during the high speed rotation, oil seal will be introduced. Now oil seals is the most use parts for rotary shaft sealing.

The differences between oil seals and other lip shape seals is the lip having better elasticity. The contact surface is very narrow (about 0.5 mm) and the force distribution is triangular,  the lip and spring create and increase the force onto shaft and have good adhesive reinforce. So that oil seal can get better sealing performance with smaller lip radial force.

Common elastomers are: FKM, ACM, NBR, HNBR. In order to resist wear the compounds' durometer (hardness) is typically 70 to 85 Shore A.

Early radial shaft seals utilized rawhide as the sealing element, and many elastomeric seal companies today once were tanneries. The advent of modern elastomers
replaced rawhide, industry also added a garter spring which helps the sealing lip compensate for lip wear and elastomer material changes.

In recent years, PTFE are started using for sealing lip material and got widely applications.

Valve Stem Seals

The role of valve stem seals is to limit the amount of oil which enters the cylinders by way of the valve guides. At the same time, the seal must let a certain amount of oil into lubricate valve stem and valve guide in order to avoid excessive wear and/or sticking.

The first seals were made of polyacylic elastomer. As valve stem seal technology progressed, fluoro-elastomers (FPM) became the material of choice.

The valve stem seal also helps limit the pollution resulting from the combusion of the lubricant and the possible contamination and destruction fo the catalytic converter by certain components present in the oil.

Valve stem seal type has VA3, VA9, also VA0, VA1, VA2, VA4, VA5, VA6, VA7, VA8 etc.