Apr. 17, 2023
Oil Seals
An oil seal is a type of seal used in various industrial equipment to close the gap between its moving and non-moving components. These oil seals help prevent lubricant leakage at high pressures and block foreign components from entering the machinery. With such an important role to play, these oil seals must be chosen carefully. This post discusses the types of oil seals and also guides you through the important factors to choose an appropriate oil seal for your industry.
Types of Oil Seals – Based on Materials
There is a wide range of seals to select according to the type of material. Some of the types of oil seals are as follows:
Rubber Oil Seals:
Rubber seals are the most common types of sealing solutions preferred for tight sealing. Rubber seals are corrosion resistant and are used in both high and low-pressure applications. Nitrile, polyacrylate, Viton®, silicone, and polytetrafluoroethylene are a few common types of rubber materials used for this purpose. Each material possesses the typical capability, so, you must choose the rubber material carefully for your application.
Rubber seals are the most common types of sealing solutions preferred for tight sealing. Rubber seals are corrosion resistant and are used in both high and low-pressure applications. Nitrile, polyacrylate, Viton®, silicone, and polytetrafluoroethylene are a few common types of rubber materials used for this purpose. Each material possesses the typical capability, so, you must choose the rubber material carefully for your application.
Metal Cased Oil Seals:
These seals feature stamped metal cases with an elastomer bonded sealing lip. Carbon steel is the metal used for making the case. The case protects the lip seal during installation. Metal encased seals are generally used for high-pressure or high-temperature applications.
These seals feature stamped metal cases with an elastomer bonded sealing lip. Carbon steel is the metal used for making the case. The case protects the lip seal during installation. Metal encased seals are generally used for high-pressure or high-temperature applications.
Leather Oil Seals:
These seals possess good running properties and are generally preferred for abrasive applications. The seals are usually used for shafts that possess surface roughness higher than rubber seals.
These seals possess good running properties and are generally preferred for abrasive applications. The seals are usually used for shafts that possess surface roughness higher than rubber seals.
7 Important Factors to Consider When Choosing Oil Seals
With varieties of seals available, choosing the right seal for application can be a daunting task. The following factors will help make the right selection.
Lubricant: If choosing lubricated seals ensure they are continuously lubricated with oil that possesses appropriate viscosity required for the application and the lubricant is compatible with the elastomer material of seals.
Shaft Finishing: A good surface finishing of shafts gives a very effective oil sealing. The ground or polished shafts with concentric finish marks provide the best sealing that prevents leakage even during the shaft rotations. Hence, it is important to make sure that the shaft finishing is well maintained.
Shaft and Bore Tolerance: The seals must be strong enough to tolerate the pressure and vibrations caused by shaft and bores. The authenticity of metal and elastomer material is something that makes the shaft and bore tolerance possible. Therefore, check if the material meets these requirements before buying the seal.
Shaft Hardness: The life expectancy of a seal is measured on the basis of the hardness of its shaft. A shaft must possess a Rockwell hardness of 30 or above. When a seal is exposed to abrasive contaminants or high pressure, this RC hardness protects the seal from getting damaged. Hence, it is an essential factor.
Temperature: The temperature of the process should not exceed the temperature of the seal elastomer. Any increase or decrease in temperature may affect the sealing capability of the seal. Hence, it is an important point to be considered.
Pressure: Most seals are designed for applications where they may be subjected to pressures as low as 8 psi. However, if they are subjected to even low pressures then pressure relief must be ensured.
Shaft Speed: Shaft speed depends on many factors including shaft finish, its concentricity, the type of liquid being transferred, and the type of oil seal material. So each of these factors must be considered to achieve a maximum shaft speed.
In addition to the above-given factors, sourcing high-quality seals from a trusted manufacturer are quite important. SSP Seals provides high-quality
In addition to the above-given factors, sourcing high-quality seals from a trusted manufacturer are quite important. SSP Seals provides high-quality oil seals for industrial applications in automotive, oil and energy, and other sectors. The company can provide seals made of a wide range of materials including PTFE, Viton, Silicone, Nitrile, and so on.
Shaft seals, dirt seals, grease seals, lip seals, and many other names are only a few of the many names given to oil seals. They are simple components used in rotary shaft machinery to keep oil from leaking and impurities like dust, dirt, and water out. However, an oil seal’s most crucial role is to safeguard all ball, sleeve, and roller bearing types found in rotating shafts. Additionally, the seals stop blending two fluids that shouldn’t mix, such as water and oil.
A mechanical tool called an oil seal keeps lubricant from leaking out of the machine. It accomplishes its goal by sealing the equipment’s moving and stationary parts. Additionally, it prevents impurities from getting inside the machine and shortens its lifespan, an important role it completes.
Numerous oil seals exist, including PTFE lip oil seals, rubber fabric oil seals, and rotating V-seals.
An oil seal kit is a set of oil seals with the necessary dimensions and desired characteristics. An oil seal kit is more cost-effective and advantageous than buying individual oil seals.
Oil or other seals can be used for grease and oil seals. A flexible lip, radial lip, or rotating shaft seal are different names for an oil seal. Single lip, double lip, triple lip, and four or more lips are frequent configurations.
Double dust lip seal
A seal with a garter spring design is the Double Dust Lip (DDL) seal. It has two dust lips, as the name would imply, plus a fluid lip with a garter spring to keep the lip firmly attached to the wear ring. Given the ongoing evolution of bearing seal designs, this seal would be considered a starting seal. For more than 50 years, this design has been the workhorse of the freight business; it still is in some regions. NBC Brenco Bearing Seal performs the fundamental task of keeping contaminants and grease out. Because of the garter spring, this seal would add the most torque and temperature to the bearing.
Efficiency plus bearing seals
Due to eliminating the fluid lip using poly inserts and rotors, the Efficiency Plus (EP) seal has a reduced torque value of fewer than 15 in-lbs. Although it features a triple dust lip rather than a double dust lip, the dust lip is still a molded component of the design. A labyrinth-like insert and rotor interlock each other to replace the fluid lip. NBC Brenco labyrinth provides excellent grease while lowering the torque required to rotate the seal.
Other types of oil seal and grease seals include:
Single lip oil seal
Metal cased
All rubber or polymers
Internal orientation
External orientation
Axial orientation
Spring-energized
Purpose of oil seal
To serve as a physical barrier that keeps the lubricant in the designated area.
To stop the lubricating oil from leaking outside despite high oil pressure.
Act as a barrier to keep debris, contaminants, and other outside elements out of the system containing the lubricating oil.
Why are sealed bearings favored over the unsealed alternative? Why ought sealed ball bearings be preferred to unsealed ones? What advantages can sealed ball bearings offer?
Worry-free lubrication
No contact
Self-contained
What are bearing isolators?
Dynamic seals called bearing isolators are used to shield bearings from external impurities. They are revolving (rotor) and stationary (stator) elements. O-rings or strong seals are used in some bearing isolators, while they are constructed like labyrinths in others.
Different types of bearing seals
For many bearings, a good bearing seal is essential. Bearing seals perform a dual function by keeping lubricants from leaking out while preventing impurities from entering your parts. Both procedures can help your bearings last longer, but choosing the proper seals for your components is critical. Different types of bearing seals include:
Contact seals
No-contact seals
Labyrinth seals
Pick the proper seal for your bearing with the NBC bearing
.
Several variables, including maximum temperatures, required lubricants, available space, and more, may influence your choice of bearing seal. Each factor can affect the type of bearing best for your application, the amount of material required, and other factors.
Although the choice of seals is crucial to the effectiveness of your bearings, you don’t have to make that choice alone. Our experts at NBC bearings can collaborate with you to identify the bearings and bearing seals that provide the best, most affordable solution for your application, environment, and finished product.
Are you looking to keep your machinery free from any unwanted leakages but aren’t sure which rotary shaft seal is right for your needs? This guide will provide you with everything you need to know in order to select the right one for your application.
Oil seals, which are also known as rotary shaft seals, fluid seals or grease seals, play an important role in closing down the gaps between moving and stationary elements of mechanical equipment.
By preventing lubricants from escaping, they protect key components of machinery from being damaged by leaks of various fluids. Everything from car engines to assembly machines use these oil seals to remain free from any harmful interactions that can cause serious and expensive damage to any of their critical parts.
There are a wide range of oil seals to select from for any number of uses, so this guide will break down the most common seals to help you choose the right one for whatever piece of machinery you are working on.
What are rotary shaft seals?
Rotary shaft or oil seals are placed between moving and stationary pieces of machinery to ensure that contaminants, moisture, corrosive materials and abrasives do not damage the various components. They can also prevent unwanted mixing of fluids, including water and oil combining within a machine.
How are Oil Seals made?
First, an elastomer, most often nitrile, is vulcanised to a metal ring. This creates a stiffening effect that includes a specialised metal tension spring directly behind the sealing lip, keeping the oil seal firmly in place against the moving part.
Oil Seal Materials
There are many different materials used to manufacture oil seals.
Leather Oil Seals – Leather Seals, also known as Type L Oil Seals, are most common in components that are subject to dirt and poor lubrication. Since they come pre-lubricated and are able to absorb fluids, leather oil seals are able to provide sealing properties in conditions that synthetic rubber is unable to.
Synthetic Rubber Oil Seals – Styrene Butadiene Rubber oil seals, or just SBR oil seals, offer strong resistance to abrasions and lesions, making them an ideal seal for fast-moving machinery. With the ability to withstand extreme temperatures with its heat-aging qualities, they can be used in outdoor components. They are also seen as more cost-effective oil seals than natural rubber.
Nitrile Oil Seals – Nitrile oil seals, which is the commonly used term for acrylonitrile-butadiene rubber seals, is a very good general-purpose option due to the flexibility of use across a variety of components. The resistance is strong against fats, hot water, gasoline, mineral oils, grease and animal oils, making them the most often-used oil seals. They do not have a wide temperature range, making them a poor choice for machinery that can see extreme changes in temperature.
Viton Oil Seals – A synthetic rubber and fluoropolymer elastomer, Viton is used to make oil seals that provide resistance in both high temperature, up to 250°C and low compression set components. They also offer a high resistance to chemicals and abrasions, so they can be used in elements that regularly interact with petroleum and solvents.
Polyacrylate Oil Seals – Mostly selected for automotive and transmission uses, polyacrylate seals are able to withstand fuel, oil, ozone, sunlight and weather when used. With cars exposed to all these different fluids and elements, they are the perfect choice. However, they should not be used in low temperatures, as their flexibility weakens when cold.
Silicone Oil Seals – Designed to absorb lubricants in order to lessen wear and friction, silicone rotary shafts also offer high thermal resistance and a large temperature range. But, they do not handle abrasions well or interact with oxidized oils.
PTFE Oil Seals – A relatively new and exciting oil seal, the use of polytetrafluoroethylene means that they can withstand dry or unlubricated operations. With a massive thermal range of -130ºC to +200ºC and a strong resistance to chemicals, they are considered to be the future of rotary shaft seals.
How to Choose the Right Oil Seal
There are several key factors to consider when you are selecting the oil seals for your next project to ensure that you protect your machinery from immediate and long-term damage.
Pressure – Many oil seals can only withstand low-pressure applications, so understanding the compression set of your components is key.
Temperature – Just like pressure, the temperature that your oil seal will be operating in must be known so that you can choose one that can withstand the heat or cold. PTFE have the widest range of temperature, making them useful for machines who can see usage in extreme weather or elements.
Shaft Speed – Considering the speed that the shaft will be moving, the runout, the housing bore and the type of oil being sealed is vital to making sure you select an oil seal that will not suffer from abrasions or spiralling.
Fluid Types – Various oil seals are able to withstand interactions with oils, fuels, grease, water and more. Knowing what type of fluid the rotary shaft seal will be in constant contact with will ensure the longevity of the seal and surrounding components.
Lubricant Amount – Seals will always perform best when lubricated, however in some machines there are more likely to be dry spells. For these cases, selecting a leather or PTFE seal will be beneficial, as both can operate with less lubrication than others.
can be difficult to get right, especially if you do not have the original machine specifications. Thankfully, there are a few ways to identify oil seals; from their design, size and material. As there are hundreds of different oil seals available on the market, this guide will cover the four most common design types. Typically available with either a single or double lip, in Nitrile or Viton Rubber Material.
Firstly, the oil seals covered in this guide classify the single lip as the inner diameter at the bottom of the component. The single lip is vital to the function of the seal by containing the oil, grease or lubricant. The only difference between a single and double lip is the additional rubber lip on the top of the oil seal which helps prevent dust or dirt from coming close to the shaft. Identifying the oil seal lip can be misinterpreted with a visual inspection alone. For or this reason, you should press along the inner diameter at the top of the seal, if you feel a ridge with a slight movement or give it is highly likely you have a double-lipped oil seal.
Industry retailers use unique codes to identify oil seals worldwide. The most common lip style designations are 21 (single lip) and 23 (double lip), please read our Oil Seal Cross Reference Guide for more detailed information.
Fully covered outer diameter for excellent sealing. This oil seal is fully enclosed in a rubber material and is the most widely used type of oil seal. Great resistance to thermal cycling, temperatures and different chemical resistance.
Economic metal outer diameter for standard applications. This is an economical oil seal where the metal is exposed on one side and offers a closer fitting between the oil seal and housing or bore. Due to this, it has limited use with sealing thin liquids or gases.
The same design as type B with an additional inner case for greater structural rigidity. This type of oil seal is typically used in heavy-duty engineering machinery or large diameter sized seals
The same design as type A with corrosion protected metal case and stainless-steel garter spring. Suitable for use with a wide range of fuels and chemicals.
Nitrile or NBR is black in color, whereas, Viton or FKM is usually a brownish color. To understand the main comparisons between the two compounds read our Nitrile vs. Viton article.
Finally, Polymax part codes follow the same pattern as our O-rings – inner diameter, outer diameter, and height. This is different from the industry-standard convention, whereby imperial oil seals follow – outer diameter, inner diameter, and height.
We hope the information in this article helps you identify the correct oil seal for your application. If you have any queries feel free to call us.
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FOUNDED IN 1993
China SBT Oil Seal is an international company integrating design, research and development, production and processing.
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Won many honorary certificates through a number of patented inventions
