We can’t emphasise enough how important it is to choose the right oil seal to keep your application functioning, and functioning well.
Not every oil seal is the same. Manufactured using various material elastomers and to suit a range of dimensions, seals are as unique as the application they are intended for.
However, oil seals do all aim to perform the same function – to prevent leaks and stop contamination entering the application.
These seals also typically have a single or double lip, and the most common materials used in the makeup of these types of sealing products include Nitrile, Viton, or rubber.
Seals and Gaskets
Helping to close (seal) the gap between stationary and moving parts, oil seals prevent leaks and stop contamination due to the flexible lip rubbing against the shaft as it rotates.
The DIN is the standard that specifies a seal’s dimensions, requirements for materials, use and installation, and more.
Therefore, helping to find the right seal for the intended application, all seals and gaskets come with a unique coding system to help identify the type of seal and its features and properties. This is necessary to allow you to choose the correct seal and to record what seals work best in certain applications.
The most popular types of oil seals that we see are the single lip 21 and the double lip 23.
A single lip seal is what contains the oil, grease, or lubricant. Primarily, it does exactly what it is intended to do as an oil seal. A standard oil ring will consist of a metal ring as the inner to provide stability, with the spring on the lip providing additional support and preventing leaks from occurring.
A double-lip seal is a seal that has an additional rubber lip to prevent dust or dirt from entering the shaft, increasing the seal’s longevity. This second additional layer will feel like a ridge along the inner diameter at the top of the seal itself, ultimately providing extra protection.
Type of Oil Seals
The most common types of oil seals are rubber or metal cases.
Rubber-cased seals (A) = an excellent sealing solution encompassing a rubber-covered lip seal, with the oil seal fully enclosed. This type of oil seal is the most popular as it provides great thermal resistance, as well as temperature and chemical resistance. Often used when metal-cased seals have the potential to fail, this type of seal can’t rust, provides a tight fit as it is fast expanding, and can seal even when housing is slightly damaged.
Metal-cased seals (B) = a seal with a metal outer diameter; this type of seal is suitable for more standard applications. As the metal is exposed on one side, you can achieve a closer fit; when used with the same material application, it can provide equal contraction and expansion, and this type of seal can be more cost-effective than rubber seals. However, these seals should be used cautiously as they aren’t suitable for sealing thin liquids or gases.
C = with a reinforced metal insert, similar to seal type B, this seal has the extra benefit of an additional inner case, making it incredibly robust. Often found in heavy-duty machinery or equipment that requires a larger-size sealing solution.
F = a seal that operates as a stainless-steel garter spring, with a similar design to seal type A, but with the added benefit of a metal case that provides corrosion protection; this type of seal is most suitable for a range of fuels and chemicals. Connected at each shaft end to create a circular shape, garter springs help maintain the radial force around a shaft’s surface.
R = a rubber seal with a carbon steel insert and a rubber outer; this type of seal provides an effective sealing solution; with press fitting, it can also provide static sealing and comes with a good lifespan.
Bearing isolators = a dynamic seal that offers protection from a range of external contaminants.
There are various lip materials available for oil seals, some of the most common:
- Natural Rubber
- Stainless Steel
- And so much more.
Installation of oil seals depends on the seal aim, direction, intention and also placement within the shaft and housing itself.
You will also need to consider dimension requirements. For example, inner and outer diameters, diameter of the housing, seal thickness, cross sections, and more.
Then, there are also service limits such as application operating speed, applied pressure, vacuum rotation, fluctuating temperatures, external influences etc.
There are various types of oil seals to fit a range of applications, and it’s vital that you find the right oil seal for you.