What is an Oil Seal?

Oil seals, also referred to as shaft seals, are widely used to prevent the leakage of medium (such as oils and grease) along a rotating shaft. This leak prevention is primarily achieved by the sealing element which can be made from a wide range of materials that are chosen according to each application. They are commonly used in gearboxes, hydraulic cylinders, and related components.

Purpose of an Oil Seal

An oil seal is designed to perform three major functions: to prevent lubricants from leaking outside the seal even under high pressure, to act as a barrier to retain the lubricating oil, and to prevent dirt and other contaminants from entering the unit.

Shop for Oil Seals

Construction of an Oil Seal

Oil seals normally consist of three basic components: the sealing element, the metal case, and garter spring.

1. Sealing Element

The sealing element makes up the interior of the oil seal, and the materials commonly used are:

• a. Nitrile Rubber (NBR) – this is the most commonly used material. It has good heat resistance properties and has good resistance to salt solutions, oils, hydraulic oils, and gasoline. Operating temperatures are recommended from -40 to 248⁰ F (-40 to 120 deg.C). Nitrile also functions well in a dry environment, but only for intermittent periods. The disadvantage of this material is poor chemical resistance.
• b. Polyacrylate Rubber (PA) – also known as acrylic rubber, this material has better heat resistance than nitrile. PA is also recommended for a high surface speed environment. Operation temperatures are recommended from -4 to 302⁰ F (-20 to 150⁰ C). Polyacrylate rubber should not be used with water or in temperature below -4⁰ F (20⁰ C).
• c. Silicone Rubber (SI) – these compounds operate effectively in a broad temperature range of -58⁰ F to 356⁰ F (-50 to 180⁰ C). Silicone rubber is a leading choice for its resistance to both low temperatures and heat. The high lubricant absorbency of the material minimizes friction and wear. These oil seals are usually used as crankshaft seals. Silicone has poor resistance to hydrolysis and should not be used in oxidized or hypoid oils.
• d. Fluorocarbon Rubber (FKM) – is widely known under the Chemours (formerly Dupont™) trade name of Viton® and offers the best resistance to chemicals and superior performance to high temperatures.

2. Metal Case

The metal case is the exterior (or frame) of the oil seal, the principal function of which is to give rigidity and strength to the seal. The material of the case must be selected depending on the environment where the seals are to be used. Often the metal case is covered by the same rubber material used in the sealing element, which also helps seal the exterior of the oil seal in the housing bore. Common case material types are:

• a. Carbon Steel – the most common material used in oil seals.
• b. Stainless Steel – for applications that require resistance to water, chemicals, or corrosion. (Stainless steel metal cases are also recommended for many FDA applications.)

3. Garter Spring

The garter spring is located at the end of the primary sealing lip and used to apply pressure to the sealing lip against the shaft. Common garter spring material types are:

• a. Carbon Steel – which is used in conjunction with regular lubricants.
• b. Stainless Steel – which is used when resistance to water, seawater, and chemicals are involved.

Oil Seals From Global O-Ring and Seal

Global O-Ring and Seal carries a full line of oil seals in all industry standard sizes and has the ability to create custom oil seals. If you are a distributor or user of oil seals who may have need for our services, contact us today to speak with one of our team members, request a no-obligation quote, or place an order from our extensive inventory at GlobalOring.com.

Shop for Oil Seals

Want to learn more? Read “Oil Seals 101, Part 2”.

Top 8 Installation Tips for Oil Seals

Rubber oil seals play a significant role in preventing contamination and leakage in various applications, from automotive engines to industrial machinery. Although widely used seals, many users fail to get the results as expected mainly due to improper installation in applications. Understanding what rubber oil seals are and how to install them correctly is essential for ensuring the efficient and reliable operation of these systems. Would you like to get a clear clarity about oil seals and how to install them correctly in your applications? If yes, continue reading this post.

What are Rubber Oil Seals?

Rubber oil seals, also known as oil seals, are popularly used components in various industrial applications especially to prevent the leakage of fluids, such as oils or lubricants, from machinery or equipment. Made to fit tightly around rotating or moving shafts, these industrial oil seals, efficaciously create a barrier between the inner workings of the machine and the external environment.


As they are made from synthetic rubber materials, such as nitrile rubber, these seals offer excellent sealing properties, along with resistance to oil and other fluids. The rubber material is molded into a ring shape, often with a metal casing or reinforcement to provide structural support and ensure durability.

Steps to Install Rubber Oil Seals Properly

Following the steps below leads to a proper installation of industrial rubber seals when used in your applications.

1. Prepare the Surface: Take out the oil seals from their packaging only just before installation. Before installing the rubber oil seal, make sure the surface where it will be installed is clean and free of any debris or contaminants. Wipe the surface with a clean cloth or use a solvent if necessary to remove any grease or oil.
2. Inspect the Rubber Oil Seal: Before blindly installing the seal, have a thorough check and inspect the rubber oil seal for any damage or defects. Ensure to use a seal of the correct size and type for your application.
3. Apply lubrication: Apply a thin layer of lubricant to the industrial oil seal. This will help the seal slide into place smoothly and prevent any damage during installation.
4. Position the seal: Now carefully position the rubber oil seal on the designated area. Ensure that the seal is aligned correctly and evenly with the surface. Avoid stretching or distorting the seal during this step.
5. Use a seal installation tool: To securely install the seal, it is advisable to use a seal installation tool. This tool is specifically designed to prevent any damage to the seal and ensure a proper fit. If you need advice on the right tool, get in touch with the oil seal manufacturer.
6. Apply consistent pressure: When installing the seal, ensure to apply consistent and even pressure around its circumference. You can gradually push the seal into its housing with a gentle, tapping motion. Applying excessive force can deform or damage the seal.
7. Check the seal: Once done with the installation, double-check that it is seated correctly and evenly. Ensure that the seal is flush with the surface and there are no gaps or misalignments.
8. Test for leaks: Testing the rubber oil seal for leaks is the last and crucial step. Apply appropriate fluid or pressure to the sealed area and carefully observe for any signs of leakage. You may make necessary adjustments or repairs to ensure proper sealing.

If you are still confused and have more doubts about rubber seals and their installation, get in touch with trusted oil seal manufacturers such as SSP Seals. With their expertise and experience, they can provide you with comprehensive information and guidance to ensure the successful use and installation of these seals.

Related Post

Modify: Mar. 22, 2023

Oil seal is the customary name of general seals, which is simply the seal of lubricating oil. It is used to seal grease (oil is a common liquid substance in the transmission system, also refers to the general meaning of liquid substances) mechanical components, it will drive parts in need of lubrication and output parts of isolation, so as not to let lubricant leakage. Static and dynamic seals (general reciprocating motion) are called oil seals with seals. The representative form of oil seal is TC oil seal, which is a double lip oil seal with self-tightening spring completely covered by rubber. Generally speaking, oil seal often refers to this TC skeleton oil seal.

Common materials for oil seals are: Nitrile rubber (NBR), fluorine rubber(FKM), silicone rubber, acrylic rubber, polyurethane, polytetrafluoroethylene and so on.

1. NBR

It has good heat resistance, wear resistance, resistance to various lubricants, greases, oil and gas mixtures, suitable for temperature - 30 - 120 degrees Celsius, but can no longer be used in phosphate hydraulic oil and gear oil containing extreme pressure additives, stable performance in gasoline and mineral oil with low aniline point.

2. Polyacrylate rubber (ACM)

Excellent oil and heat resistance, abrasion resistance, ozone resistance, ultraviolet radiation resistance, especially extreme pressure fluid containing lubricants, gear oil, motor oil, oil series hydraulic oil, etc., suitable for - 30 - 150 degrees Celsius range of work.

3. Fluororubber (FPM)

Aging resistance, heat resistance, oil resistance, almost applicable to all lubricants, fuel oils, gasoline, oil containing extreme pressure additives is not easy to harden, but cold resistance, high temperature wear resistance is poor, compression deformation is large, suitable for temperature - 20 ~ 250 degrees Celsius.

4. silicone rubber

It has outstanding resistance to high and low temperatures, can be used at 150 degrees Celsius for a long time without performance change, can be used at 200 degrees Celsius for 10,000 hours continuously, and can maintain its unique use flexibility, ozone resistance and weather resistance in the operating temperature range of - 70-260.

5. Teflon

It has outstanding chemical stability, thermal stability, friction reduction and self-lubrication. Its pyrolysis temperature is over 400. Therefore, it can work normally in the temperature range of - 200 - 300 degrees Celsius. Except for free fluorine and alkali metals, it has excellent corrosion resistance to chemicals, solvents, hydroxides and acids.

Nitrile butadiene rubber (NBR) and fluorine rubber (FBR) are widely used oil seals. The former has low cost, but its temperature resistance and sealing performance have been improved obviously, but the cost is higher, and it still has some bad common characteristics of ordinary rubber materials, such as poor wear resistance, short service life, especially sensitive to the eccentricity of the shaft, etc. Leakage phenomenon is still widespread. PTFE oil seal is a product with high technology content, which is the direction of oil seal development in the future.

Attention:

When choosing the material of oil seal, the compatibility of material to working medium, the adaptability to working temperature range and the ability of lip edge to follow the rotating axis at high speed must be considered. Generally, the temperature of lip edge is higher than that of working medium at 20-50 C. Attention should be paid to the selection of oil seal materials. The working range of oil seals is related to the materials used in oil seals: NBR, ACM, FPM and NBR.