Also known as grease seals, rotary shaft seals, or fluid seals, oil seals play a pivotal role in mechanical equipment. They are often overlooked because they are a small part of the machine, but when these oil seals fail, the consequences can be huge, like seal leakages that are costly to fix.
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From assembly machines to car engines, oil seals prevent any harmful damage from occurring, which is why you must choose the right oil seal with the highest quality. There are many kinds of oil seals, all of which have several uses.
This article will guide you through the most common factors you should look for when buying oil seals to help you choose the right one for the machinery you’re working on.
Improper installation and poor-quality oil seals are some of the reasons that pieces of machinery get damaged. When choosing an oil seal, consider the following factors.
The temperature range of the seal elastomer should match the temperature range of where you’ll install the seal. For example, high-temperature and high-pressure environments need more durable rubber, like Viton. If the oil seal is exposed to extreme temperatures outside of the elastomer’s range, the sealing lip may harden, break, and crack.
The oil seal’s material matters, as it can determine how well it performs depending on its use. Sealing elements can come in leather, silicone, synthetic rubber, Viton, nitrile, and polyacrylate. Nitrile is good for general purposes, as it’s flexible and resistant against oils, hot water, and gasoline. However, it doesn’t do well in extremely high temperatures. Meanwhile, silicone oil seals lessen wear and tear by absorbing lubricants. They have a wide temperature range and high thermal resistance, too.
Understanding the compression requirements of your components is important. Most ordinary oil seals are designed for very low-pressure applications (about 8 psi or less). If the intended application has high pressure, you should consider choosing an oil seal ideal for high pressure or changing to a pressure-free structure.
The oil seal shouldn’t suffer from spiraling or abrasions. As such, you should consider the maximum allowable shaft speed, runout, type of oil seal material, type of fluid being sealed, and housing bore and shaft concentricity before buying an oil seal.
Close shaft and bore tolerances should be present if you want the best seal performance. It would be best to consider the shaft’s vibration, eccentricity, and end play.
You must align bore and shaft centers because misalignment can shorten the oil seal’s life cycle due to the excessive wear concentrated on only one side of the sealing lip.
It would be best if you kept runout to a minimum. When the center of rotation moves, it’s usually caused by a shaft whip or bearing wobble. When you add misalignment, then you’ll face a greater problem. Contrary to common practice, installing flexible couplings won’t correct misalignment, which is why you need the right oil seal to prevent all these issues from arising.
The quality of the oil seal affects its service life. The higher the quality, the longer the lifespan, reducing wear and tear and increasing your ROI through lower maintenance costs. While wear and tear issues are inevitable, you should mitigate them by using materials that last long. Here, the first step to ensuring quality oil seals is purchasing from a reputable oil seal supplier.
When shafts have a Rockwell (RC) hardness of 30 or more, you can expect the oil seal to have a longer seal life. For shafts exposed to more abrasive contamination, your oil seal should handle RC 60.
You can tell that you have effective sealing if the shaft surface finish is in excellent condition. Sealing performance is greatly influenced by the spiral lead and the direction of the finish tool marks.
You’ll get the best sealing results when the shafts are ground or polished with concentric (no spiral lead) finish marks. If the shaft can’t help but have spiral finish leads, they should lead toward the fluid when the shaft rotates.
Oil or lubricants play a significant role in improving the oil seal’s performance. You should choose a lubricant compatible with the seal lip elastomer material and the right viscosity for the application. Incompatible lubrication can result in the wearing out of the oil seal.
An example of a lubricant you can use is Permatex Anti-Seize Lubricant, a highly refined blend of graphite, aluminum, and copper lubricants.
Oil seals come in various sizes, styles, and materials. Hence, it can be challenging to pick the right type for your needs. Use the factors above to guide you throughout your oil seal selection process. If you’re looking for top-of-the-line oil seals, Simplex is a premier distributor of oil seals and premium industrial and engineering parts in the Philippines. Visit our shop today to get started!
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
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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.
Replacing a critical component 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 colour, whereas, Viton or FKM is usually a brownish colour. 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.
Design: Single-lip oil seals have a single sealing lip that contacts the shaft, while double-lip oil seals have two sealing lips, with the outer lip designed to prevent contaminants from entering the machinery and the inner lip to retain lubricants.
Sealing Capabilities: Single-lip oil seals may not be as effective as double-lip seals in preventing contamination, as they have only one sealing surface. Double-lip oil seals offer improved sealing capabilities due to the presence of two sealing lips. The outer lip protects the seal from dust, dirt, and other contaminants, while the inner lip retains the lubricant and prevents it from leaking out.
Friction: Single-lip oil seals have lower friction, which allows them to be used in high-speed applications. Double-lip seals may have higher friction, which can limit their use in high-speed applications.
Cost: Single-lip oil seals are typically less expensive than double lip seals.
The choice of single lip and double lip oil seal depends on the specific application requirements, such as operating speed, pressure, temperature and pollutant exposure. Consulting the seal manufacturer (NNK) or engineer can help to ensure that the appropriate seal design is selected for a specific machine and application.