Everybody knows what the term seal means but only a few know what an oil seal is. Besides closing the gap between two things, a seal has more functions to do and surprisingly they are available in various shapes, sizes and components to suit different requirements of different machines. Here’s a brief look at them.
Basic understanding
Both oil seals and o-rings can be used in hydraulic systems, pipes, pistons, pumps, etc. Oil seals are mainly used for sealing a rotating component. So they are also known as rotating seals. O-rings are also used for such purpose. The function of an oil seal includes protecting shafts and bearings from dirt and grease while preventing escape of machine fluid.
A sog oil seal has an inner flexible part and an outer metal part which is joined with the former by chemical adhesive components. In this the inner flexible part actually does the work of sealing. The sealing part is created with rubber, either natural or synthetic. The sealing lip is formed by removing the flash at the sealing edge at the time of molding. A sharp sealing edge gives proper pressure on the shaft to block leakage.
An O-ring is generally lightweight and flexible. So when the machine exerts pressure, it can flex itself to follow the component parts that are to be sealed. It has long shelf life. It offers effective sealing benefit under varying or constant temperature and pressure. Despite these advantages, oil seals are the most sought-after choices in industrial uses due to their versatile practical applications.
Which one to choose
A usual oil seal has an outer metal part with an inner flexible part which is made of rubber and attached to the outer metal at the time of vulcanization. This sort of seal has no loose part and hence it prevents fluid leakage quite well. If a machine has a small space, this perfectly fits in.
There’s another type of seal that has metal outer part encased in rubber. It offers wider tolerance and its resilient rubber layer keeps a check on the irregularities of the seal housing surface. These metal seals have longer endurance power under extreme pressure and temperature.
On the other hand, automotive seals are a bit more complex. They have dust lips that are used to keep the impurities away from the oil lip seals. They come with undercuts that prevent bending or breaking of the seal or sealing shaft. Fluoroelastomer components are generally used for this sort of seals. They have high tolerance of pressure and temperature. This helps avoid tearing any part at the time of demolding.
Note that there are several other types of seal designs are now available in the market based on their mechanical applications. So before you buy something, understand what is best for your machine.