Machines with many moving parts often use oil to lubricate and protect mechanical components. However, when using oil, it’s important to take steps to prevent costly and potentially hazardous leaks. Oil seals offer a simple but effective solution, closing spaces between mechanical components to prevent lubricants from escaping. As an added benefit, oil seals also prevent moisture or chemical contaminants from breaching gaps in the machinery.
MSP Seals offers a full range of oil seals to prevent oil leaks and protect sensitive machinery from damage.
Oil seals, alternatively known as rotary shaft seals or lip seals, are flexible rings of elastomer that secure the boundaries between stationary and moving components in a machine. These rings are flexible but durable, resisting wear from friction and exposure to oil. These properties allow oil seals to keep lubricants in a machine while keeping contaminants out. In doing so, oil seals prolong the working life of rotating shafts and precision bearings, ensuring that moving parts retain the lubrication they need for smooth performance.
MSP’s oil seals are designed to withstand extreme working environments, offering excellent durability and low friction properties to promote long working life. Our oil seals are lightweight and have a long shelf life, so they won’t become brittle or interfere with machine operation. Compared to standard seals, they offer improved performance in a convenient and easy-to-install form, making them the perfect solution for rotary shaft sealing.
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Oil seals can be made from several types of polymers, but one of the most effective is polytetrafluoroethylene, or PTFE. PTFE has exceptionally low friction, allowing it to resist abrasion and retain its integrity over time. PTFE is also resistant to high temperatures and chemical solvents, and it requires minimal lubrication, making it ideal for almost any operating environment.
Although PTFE is an excellent general-purpose oil seal material, using elastomers can also be appropriate, including silicone, nitrile, and EPDM. Materials are often chosen based on specific application requirements, such as the need to withstand specific chemicals. The mechanical properties of the rotary shaft, including shaft hardness and roughness, can also impact the selection of an oil seal elastomer. For instance, a softer metal shaft often requires a softer seal material than PTFE.
Although the physical properties of the seal are important, the properties of the rotary shaft can also affect performance and longevity. One primary consideration in this respect is rotary shaft roughness, which refers to the surface unevenness of the shaft. Rotary shafts can have different degrees of roughness based on their machined tolerance. Smoother shafts have more even surfaces with finer machined tolerances.
Rotary shafts with the appropriate surface finish promote even sealing and limit premature wear due to abrasion. Generally, oil seals perform better when they are paired with smooth, properly finished rotary shafts. However, some surface roughness is desirable as it allows a film of lubricant to flow between the seal and the shaft, extending the longevity of the oil seal.
A rotary shaft that is too smooth exerts extra friction on the oil seal since this lubricant film cannot form. By contrast, a rotary shaft that is too rough can abrade an oil seal, causing it to fail and leak oil.
Rotary shaft hardness refers to the shaft’s resistance to indentation, which is important to consider when selecting an oil seal elastomer. The seal must always be softer than the rotary shaft to avoid damaging or wearing down the metal, leading to mechanical failure. As mentioned above, this means that softer metals are not always compatible with PTFE, which has a higher hardness relative to other polymers. PTFE seals can erode softer metal components, despite their otherwise favorable performance characteristics.
In general, harder metals are preferable for rotary shafts than softer metals, since increased hardness usually corresponds to more durable shafts and seals. However, the ideal hardness depends on a number of application-specific variables like rotation speed and pressure.
The lowest speed and lowest pressure applications can handle softer metal shafts, but hardness should still be at least 35 on the Rockwell C scale with high lubrication. When speeds or pressures are higher, the ideal rotary shafts might have hardness levels of 60 or 70+ Rc. The ideal oil seal material changes accordingly.
Despite the overall performance advantages of hard shafts, one benefit of softer rotary shafts is that they offer more leeway when working with durable oil seals. A PTFE oil seal polishes underlying metals that have hardness levels below 45 Rc, refining the surface finish for a better seal and less friction.
At higher hardness levels, this polishing effect disappears, so excess surface roughness can be more problematic. Thus, the higher the hardness required for the application, the smoother the rotary shaft needs to be to protect the working life of the oil seal. Even with proper surface finishing, seals used with very hard rotary shafts may wear out faster simply because there is less room for imperfections in the surface finish.
Whether your application uses harder metal shafts or softer ones, MSP Seals can help you identify the most appropriate oil seals for your application. Our personalized customer service team works with each client to determine your application’s key constraints, using these factors as a guide for material selection.
As experts in all manner of rotary and shaft seals, MSP offers a diverse range of oil seals and other sealing solutions, including:
We offer both standard and custom configurations for all of our sealing products, with standard and custom sizes measured in inches (SAE, ARP) and metric (JIS, DIN).
While PTFE is our preferred material for performance oil seals, we also offer seals from a wide variety of hard and soft materials. Some of our material capabilities include:
Our comprehensive sealing offerings include packaging, and labeling, as well as inventory and total cost management for clients seeking full-service sealing partners.
To learn more about MSP Seals, contact our team today. MSP is certified to ISO 9001:2015 and ISO 14001:2015. Our PTFE and sealing specialists are on hand to answer your questions and help you identify the best oil seals for your application.
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National Oil Seals, now under the Timken umbrella, are high quality products. Oil seals are used wherever shafts rotate and bearings require lubrication to work effectively. Timken’s National Oil Seal line of O-ring seal kids boast the coverage necessary for the gamut of popular applications. These handy oil seals serve to close spaces between stationary and moving components in mechanical equipment, also helping to prevent lubricant from escaping the system. They also serve to block harmful contaminants from entering machinery, especially within severe environments. National Oil Seals or other Timken products feature precision sealing designs that are well-matched for use with original equipment and in aftermarket applications as well. These seals are great for thousands of applications across many different industries like automotive, manufacturing, power transmission, and more.
Oil seals are often called dirt, fluid, or grease seals, and they serve to close spaces between stationary and moving components within mechanical machinery. They are designed to prevent the escape of lubricant necessary for proper function. They also serve to keep various contaminants from entering machinery.
Types of oil seals include:
Pro Source stocks thousands of National Oil Seals and Timken branded products such as:
Just use the "all products" search bar at the top of this page to search for specific National Oil Seal bearings and other Timken products by item number. If we don’t have what you need, we can find it!
What is an oil seal?
Oil seals, also referred to as shaft seals, are widely used to prevent the leakage of mediums such, as oils and grease, along a rotating shaft. They are commonly used in hydraulic cylinders, gearboxes, and other related components for leak prevention.
What is the purpose of an oil seal?
An oil seal has three main functions– to prevent lubricants from leaking outside the seal even under high pressure, to serve as a barrier to retain lubrication material, and to prevent dirt and contaminants from entering the unit.
What do oil seals do?
Oil seals serve to close spaces between stationary and moving components in mechanical equipment, also helping to prevent lubricant from escaping the system. They also serve to block harmful contaminants from entering machinery, especially within severe environments.
What types of oil seals are there?
There are many different types of oil seals including single and double lip, rubber or polymer, metal cased, spring loaded, and internal, external, and axial oriented.
What are the benefits of nitrile rubber oil seals?
Oil seals made from nitrile rubber offer good heat resistance properties, and are also resistant to salt solutions, oils, hydraulic oils, and gasoline They also operate well in dry environments for intermittent periods.
What are polyacrylate rubber oil seals used for?
Polyacrylate rubber oil seals are great for applications in which heat resistance is critical. They are also recommended for environments with high surface speed.
How is an oil seal constructed?
Oil seals generally consist of three basic components including the sealing element, the metal casing, and the garter spring.
Why do oil seals fail?
Severe cold can crack seals and cause them to fail. Other seals such as brake, transmission, and axle seals can be damaged due to extreme temperatures as well. Dirt and contaminants can also cause seals to slowly break down over time allowing for leaks and eventual failure.
When are oil seals used?
Oil seals are used wherever shafts rotate and bearings require lubrication to work effectively.
Is National Oil Seals owned by Timken?
Yes, National Oil Seals are distributed through The Timken Company and are stocked in their Crossville, Tennessee warehouse.
What is a National Oil Seal?
National Oil Seals, now under the Timken umbrella, are exceptional quality products. Oil seals are often referred to as dirt, fluid, or grease seals, and they serve to close spaces between stationary and moving components within mechanical machinery.
Do you have to grease oil seals?
For an oil seal to operate correctly, the seal lip must be aligned with the medium to be sealed. To allow for easier sliding over the shaft, both the shaft and the oil seal lip must be lubricated properly with grease or oil before operation.
Are National Oil Seals high quality?
Yes, National Oil Seals has been manufacturing the best in quality seals for decades, ensuring performance and industry solutions for a variety of applications.