All About Oil Seals

Oil seals go by many names, such as shaft seals, dirt seals, grease seals, lip seals, and many other variations of these. They are essentially simple devices used in rotary shaft equipment to prevent lubricant from escaping and for excluding contaminants such as dust, dirt and water. An oil seal’s most important function, however, is that it protects every type of ball, sleeve and roller bearing in the rotating shafts. The seals also prevent the integration of two different fluids that shouldn’t mix, such as oil and water.

How do oil seals work?

The basic principle of an oil seal is fairly straightforward. It is installed adjacent to the bearing, with the flexible lip against the rotating shaft and the casing pressed into the housing to hold the seal in place. It’s important that the sealing lip is lubricated to prevent it from overheating as a result of any generated friction. It’s also crucial to understand which type of seal is appropriate for your particular machinery. Before selecting your seal, consider the environment, temperature, pressure and shaft speed of your machine, as well as the type of medium the seal will come into contact with during operation. These considerations will all determine the size, colour, and type of lip material or sealing element to choose, and whether it can be sealed in or sealed out.

What material are oil seals made from?

Oil seals are made from multiple compounds and materials. Some of the oldest, still in use today, are leather and felt compounds. The trend in mass production, however, has seen a move towards synthetic rubber or elastomers. Nitrile is by far the most popular material but developments in PTFE have created a surge of interest in buyers needing seals for high-speed shaft rotation applications. Viton is taking over from the polyacrylic and silicone, as it works better in high-temperature applications and has a high-resistance to abrasion and harmful chemicals.

There are various sizes of industrial and ordinary oil seals, ranging from 0 to 33cm (13in). These varieties are also designed for different temperatures. As long as your seal matches the original equipment it’s intended for, you can be sure your machine will perform at its best. For further guidance and information regarding oil seals, don’t hesitate to contact our knowledgeable team. We are always available to assist you with your bearing, seal and gasket needs.

Oil seal: get to know all the details about this component

Fundamental things and its importance

An oil seal, also known as crankshaft retainer, is a small device, but essential to ensure the proper engine operation. It plays a key role in all moving parts of an engine, acting as a physical barrier. This mechanical seal fulfils the dual purpose of sealing a rotary shaft to maintain the necessary lubrication (avoiding leaks) and preventing other foreign matter from contaminating shafts and bearings in the rotary shaft equipment.

It is generally used in the union of two lubricated parts, so that it hermetically seals both sides. Therefore, it guarantees the proper engine operation and helps to maintain the vehicle’s distribution system in better condition.

Oil seal characteristics

Several variables must be considered when selecting oil seals. The physical dimensions and materials will vary depending on the environment of use. In addition, oil seals must remain lightweight, compact, and exhibit high self-lubrication performance.

Most oil seals consist of some basic elements that configure their structure, such as the sealing element, the metal case, and the spring:

Dust lip
: prevents particles from reaching the sealing lip.
Sealing lip
: guarantees dynamic and static sealing.
Metal case
: the metal case supports the rotary shaft seal, ensuring the structural stability.
Spring
: spiral shaped, ensures constant pressure and maintains the optimal force to the shaft.

Aspects to consider when selecting oil seals

Operating conditions such as the engine’s temperature, position, size, pressure and shaft speed largely determine which individual oil seal composition is most suitable for every individual application.

Some aspects to consider when selecting this component are:

Temperature:
The temperature within the oil seal environment is the main factor that dictates the composition of an oil seal. Generally, there is a range of set temperatures that are optimal for that material. If the operating environment is too cold, the seal may become brittle and, at high temperatures, the seal material may show increased elasticity and become leaky.
Pressure:
As the pressure increases, the radial load and the friction of the sealing lip increase in contact with the shaft. As with temperature, each oil seal has a recommended pressure for optimum performance. Excessive pressure causes the seals to wear more quickly and consequently have a shorter life.
Shaft Speed:
The speed at which an oil seal can operate effectively depends on the previously outlined conditions together with the design of the seal itself. Some designs allow for a range of maximum peripheral speeds and are therefore more suitable for larger shaft diameters. Speeds below and above the recommended range can cause friction and thus impact the sealing material.

Common causes of oil seal failure

Like any element of the engine, oil seals are subject to wear. Over time they can lead to possible leaks of lubricating liquid.

Among the most common causes of oil seal failure are:

Installation inaccuracies
, such as placing the seal in the wrong position in its housing or handling it incorrectly.
Improper
use of sealants
.
Imperfections on the shaft
(burr, corrosion, etc.), which will directly affect the service life of the oil seal.
Cracks or swelling
of the component due to extreme temperatures, causing premature deterioration of the oil seal material.
Other maintenance factors, such as
insufficient lubrication
inside the engine.

Oil leak: the most frequent failure of the oil seal

Finding oil spots under a parked vehicle can be both worrying and stressful for any vehicle owner. If the seal’s leak is small, oil may start to accumulate on the underside of the engine. But as the leak gets bigger, the oil leak will become visible in the front side of the engine.

Wear and oil loss remains two of the most frequent signs of engine seal failure and, if not paid attention to, it can give rise to a breakdown in the vehicle’s system. Regular maintenance and routine oil changes minimize the issues associated with oil seals and potential oil loss.

What are Oil Seals? 6 Things DIYers Should Know

If oil is dripping down your motorcycle’s tube, your vehicle’s performance will be affected. It won’t have as much power, and you’ll notice it acting sluggishly.

One common reason leaking occurs in engines is that debris is caught in the fork seal, holding it open and allowing oil to sneak by. So, how do you fix this? This is where the little circular devices come in—oil seals.

What Is an Oil Seal?

An oil seal is a device used to prevent dirt, dust, water, or any other foreign matter from contaminating shafts and bearings in the rotary shaft equipment. Also known as a shaft seal or dirt seal, it also blocks the leakage of lubricants such as grease and oil along a rotating shaft.

6 Things about Oil Seals You Need to Know

In this post, we’ll go over the fundamental things you need to know as a DIYer when working with oil seals.

1. Oil seals have three basic components: sealing element, metal case, and spring.

Sealing element – The sealing element constitutes the interior of the oil seal. Its purpose is to stop the fluid from leaking between the shaft and the housing. The materials typically used are fluorinated rubber, silicone, nitrile, and acrylic.
Metal case – The metal case serves as the frame of the oil seal. Its primary function is to give rigidity and strength to the seal. The material is selected depending on the environment where the seal is to be used.
Spring – The garter spring is a steel coil located at the end of the primary sealing lip. It is used to apply pressure to the sealing lip against the shaft. Typically, it is made of carbon steel or stainless steel.

2. The most common types of oil seals are rubber-cased and metal-cased.

Metal-cased oil seals are usually installed in a housing bore made of the same material. This allows for equal expansion and contraction of the materials during operation, preventing leakage. This type performs best when used in a steel housing.

Meanwhile, rubber-cased oil seals are used under conditions where a metal-cased seal can fail (for example, because of thermal expansion). Unlike the metal-cased type, these seals do not rust. Moreover, they can seal a lightly damaged housing better than metal-covered seals since, in high temperatures, rubber can provide a more stable sealability.

However, rubber-cased seals do have limitations. For example, during installation, shear stresses can build up between the seal and housing wall, causing the seal to release itself.

3. Dust and debris are common reasons for oil seal failure.

Entry of dust and debris is one of the most common reasons oil seals fail. For instance, in high-pressure applications, even the smallest sediments can create a gap in the seal, causing the oil to leak and dirt to get in.

An effective way to ensure particles do not contaminate your oil seal is to store it in a container or sealed bag away from areas where dust and debris are prevalent. Resealable, heavy-duty plastics bags and bins are ideal for keeping your shaft seal protected.

4. Protecting the shaft from damage helps optimize your oil seals’ efficiency.

Even the slightest chip or dent can cause contaminants to infiltrate your oil seal. If there are any scratches on the shaft, a leak path may develop, allowing the lubricant to drip. To protect the shaft from damage, wrap it in a mesh rubber screen and store it vertically in its compartment. This way, it can be shielded from potential cracking.

5. Sealing the grease container when not in use reduces the risk of contamination.

If you use accessories such as installation tools or grease containers, it is just as important to ensure they are taken care of. A good practice is to cover grease containers with a sealable lid when not in use. In doing so, you reduce the risk of dirt contaminating the grease and, subsequently, your oil seal.

For installation tools, make sure that they do not have any jagged edges that may damage the seal during the installation process.

6. Proper installation is key to effective oil seal performance.

Improper installation can cause your oil seal to malfunction. While being tapped into place, it can become tilted or misaligned in the bore. That being said, setting it up correctly will help ensure that the sealing process is effective.

One way to recognize an improperly installed seal is by checking whether or not there is uneven shearing of the rubber after use. If this is evident, adjust by aligning the installation tools properly before pressing the seal into place.

Oil Seals Enable Your Equipment to Operate Efficiently

Oil seals serve an important function in preventing lubricant leaks by closing in the spaces between the parts of the rotary shaft equipment. They also prevent dirt, dust, and other contaminants from clogging up the unit. Having them properly installed enables engines, pumps, and pipes to operate more efficiently.

Simplex is a premier oil seal supplier and seller of high-quality industrial and engineering parts made from various materials. Browse our online shop for the full line of our products.