Sep. 25, 2024
The area between the sealing edge and the shaft is the most important. The sealing effect is obtained by preloading the sealing lip, making its inner diameter slightly smaller than the diameter of the shaft. The garter spring ensures constant mechanical pressure and maintains the radial force on the shaft and extends the sealing edge to the defined width. Sealing is guaranteed by the surface tension of the hydrodynamic oil film between the flattened area of the seal and the shaft. The oil thickness must be between 1 and 3 mm to avoid leakage. The meniscus acts as an interface between the outside air and the fluid. Any rupture of the meniscus will cause a leak. This can occur if the shaft contains scratches along the path of the joint. Oil Seal Applications
Oil seals work by squeezing and retaining lubricant in a thin layer between the lip and the shaft. Perfect sealing is ensured by the hydrodynamic action of the rotating shaft, which in turn produces a slight pump action.
As earlier said, oil seals perform some functions that ensure the functionality of mechanical equipment and extend their lifespan. And how they do this is by retaining lubricants at all cost and not making them escape no matter how high the pressure of the machine is.
The other way oil seals work is by stopping outboard materials that can damage the machine or contaminate its lubricant. The outboard materials that the oil seal will need to stop depend on the application. However, the most common kinds are dirt, moisture, and the particles produced during manufacturing.
Standard petroleum oil has a lifespan of 30 years at 86 degrees Fahrenheit if it’s not
contaminated with moisture or any other particle. But the same oil will only last for a month at 212 degrees Fahrenheit if it’s contaminated with little water. This is why the function of an oil seal is very evident whenever it’s used.
Oil seals are used in several industrial applications to protect shafts and bearings from oil, grease, contamination, and dirt. They comprise an outer and an inner circular rings. The outer ring or disk is made of metal, while the inner one is made of rubber and hence is flexible. It is stuck onto the outer ring with the help of a chemical adhesive. There are oil seals with single lip as well double lips. The sizes of these seals depend on application requirement, and hence it is measure the inner and outer diameters, width, and so on. Also, it is crucial to choose the right type of oil seal for every application. This post discusses the way to measure and choose the oil seal for your application.
How to Choose the Right Oil Seal Type?
You may have to choose or identify the oil seal type in case of either a new equipment fitment or as a replacement for the damaged one. Here are a few pointers to identify the right seal type.
Primarily, there are single lip and double lip oil seals. The single lip is the immersed at the bottom for which the inner diameter needs to be considered.
Double lip oil seals have an extra lip at the top which protects from external contamination, dirt, and so on.
Pressing along the line of the inner diameter at the top may help determine whether the oil seal is single lip or double lip.
Check the code of the lip seal given by the manufacturer or look for a reference guide for further information regarding the oil seal type. This is because there are several types of single lip as well as double lip seals with varied configurations such as type A, B, or C single lip and type BO, ADL, double lip, and so on.
Type B seals have their outer diameter made of metal, while in case of type A it is made of rubber. In type C, there is reinforced metal added for structural stability. Likewise, there are several types of materials and their permutations and combinations.
All of these oil seals based on their materials have specific physical and chemical properties, and accordingly find applications in diverse industries. For instance, type C single lip offers structural stability and hence finds use in heavy engineering. Type A made of rubber has amazing resistance to heat, chemicals, and so on. Hence, they find application in industries where there is exposure to chemicals, abrasion, and elevated temperatures.
Before you choose the type of oil seal, it is essential to measure it, which is discussed in the next section.
How to Measure Oil Seals?
Oil seals are typically used as seals in moving parts that prevent friction as well as mixing of liquids or other elements. The oil seeps between the lip and shaft and that lifts up the lip. This creates the required gap between the lip and shaft as they should never come in contact with each other. This is basic working mechanism of oil seals. When replacing these oil seals, it is essential to measure them since they have different dimensions based on the application they are fitted in. Here are some pointers regarding their measurement.
While visual inspection may offer some clue, it may not be accurate. Hence, measuring the inner and outer diameter with the help of calipers is important.
Their measurement is much like O-rings, wherein, height, lip, type, inner and outer diameter are important factors. Material is also a factor to be considered although it cannot be measured.
Take at least three readings, preferably with a Vernier caliper. Consider the average reading if there is negligible difference among the values.
Measure the bearings and also consider the gaps.
If you want to buy
If you want to buy automotive oil seals or industrial oil seals these identification pointers may be useful. However, ensure you source them from reliable manufacturers and suppliers that can ensure leak proof seals. If you are looking for food or pharmaceutical applications, ensure the industrial oil seals are FDA approved. SSP Manufacturing Inc. has a market presence of more than three decades and offer premium quality custom oil seals for a number of industrial applications.
2. PRESSURE: Oil Seals cannot endure a lot of pressure. You need to understand your machinery’s pressure capabilities and ensure you use the correct seal to withstand its pressure levels.
3. TEMPERATURE: Similar to the pressure level, you need to know what temperature your machinery can operate at. You need to choose a seal that can withstand the heat or cold. PTFE have the widest rang of temperature, making them a safe option when you are uncertain of the range.
4. SHAFT SPEED: As different shafts move at different speeds you need to consider the runout, the housing bore, and oil type being sealed. Ensure you select a seal that will not suffer from abrasions or spiralling.
5. TYPES OF FLUID: Numerous oil seals can interact with oils, fuels, grease, water and more. However, know exactly what type of fluid the rotary shaft seal will be in contact with will ensure the longevity of the seal and the machinery.
6. AMOUNT OF LUBRICANT: Seals perform better when lubricated but some machines will go through some dry spells. When this occurs using a leather or PTFE seal will be more beneficial as those type of seals can operate with less lubrication.
Skeleton oil seals, also known as radial shaft seals or lip seals, are crucial components used to prevent leakage of lubricants and protect mechanical systems from contaminants like dust, dirt, and moisture. These seals are widely used in industries like automotive, machinery, and manufacturing, and choosing the right oil seal is essential for optimal performance and longevity. Here's a detailed guide to help you choose the correct skeleton oil seal for your specific application.
The first step in choosing a skeleton oil seal is to fully understand the specific application for which it will be used. Factors like operational speed, temperature, pressure, and the type of fluid being sealed are important considerations.
- Operating Conditions: Determine the environment in which the oil seal will operate. Consider exposure to extreme temperatures, the presence of chemicals, and whether it will be used indoors or outdoors.
- Fluid Type: Identify the type of fluid the seal will be in contact with. This could include oils, grease, or other types of lubricants. Ensure the seal material is compatible with the fluid.
- Pressure and Speed: Know the maximum operating pressure and rotational speed of the shaft. Some seals are designed to handle high-pressure environments, while others are suitable for low-pressure applications.
Rubber Skeleton Oil Seal
Skeleton oil seals are available in various materials, each with specific properties that make them suitable for different applications. The choice of material is critical as it affects the seal's resistance to heat, chemicals, and wear.
- Nitrile Rubber (NBR): The most common material for oil seals, NBR offers excellent resistance to oil and abrasion. It is suitable for temperatures ranging from -40°C to +120°C and is ideal for general-purpose sealing in industrial and automotive applications.
- Fluorocarbon (Viton): Viton seals offer higher resistance to heat and chemicals, making them suitable for high-temperature applications (up to 200°C). They are also resistant to a broader range of chemicals and are ideal for use in environments with aggressive fluids.
- Silicone Rubber: Silicone seals offer good flexibility at both high and low temperatures, but they are not as resistant to oil as NBR or Viton. Silicone is often used in applications where temperature resistance is more important than oil resistance.
- Polyurethane (PU): Known for its exceptional wear and abrasion resistance, polyurethane is often used in applications where the seal is exposed to high levels of friction and stress.
- PTFE (Teflon): PTFE oil seals offer excellent chemical resistance and operate well in a wide temperature range. They are commonly used in applications involving aggressive fluids or extremely high temperatures.
Rubber Skeleton Oil Seal
The lip design of the oil seal plays a crucial role in how well it prevents leakage and withstands pressure. Skeleton oil seals are available in different lip designs to suit varying applications.
- Single Lip (SL): Single-lip oil seals are designed to prevent leakage from the inside of the system. These are commonly used in general sealing applications where there is low pressure and no external contaminants.
- Double Lip (DL): Double-lip oil seals have an additional lip that provides extra protection against external contaminants like dust and dirt. These seals are ideal for outdoor applications or where the system is exposed to debris.
- Triple Lip (TL): These seals are used in heavy-duty applications where both high pressure and exposure to contaminants are concerns. The additional lips provide a more secure seal and extended durability.
Getting the correct size is essential to ensure a proper fit and effective sealing. Skeleton oil seals are typically specified by their inner diameter (ID), outer diameter (OD), and thickness or width.
- Inner Diameter (ID): This is the diameter of the shaft on which the seal will be installed. Measure the shaft accurately to avoid leakage or seal damage.
- Outer Diameter (OD): This is the diameter of the bore or housing where the seal will be installed. The outer diameter should be slightly larger than the bore to create a tight fit.
- Width: The width of the oil seal should match the depth of the groove or housing where it will be seated. An incorrect width can lead to misalignment and inadequate sealing.
It's important to follow the manufacturer’s specifications for the proper size. Using calipers or other precise measuring tools can help ensure an accurate fit.
Rubber Skeleton Oil Seal
The temperature range that the oil seal will be exposed to is another key factor. If the temperature exceeds the seal's capacity, it can lead to degradation, hardening, or softening of the seal material, leading to premature failure.
- Low Temperatures: For cold environments, choose materials like silicone that remain flexible even at low temperatures. NBR seals can handle cold temperatures but are not as effective in extreme cold.
- High Temperatures: For high-temperature applications, consider materials like Viton or PTFE that can withstand heat without losing their sealing properties.
Always ensure the material and design you select are capable of operating at the upper and lower limits of your application’s temperature range.
While most skeleton oil seals are designed for low-pressure applications, some seals are specifically designed to handle moderate to high pressure. If your application involves significant pressure levels, be sure to choose an oil seal that can withstand the force without failing.
- Low-Pressure Seals: For most general-purpose applications, standard skeleton oil seals can handle low pressures effectively.
- High-Pressure Seals: For higher-pressure environments, choose seals with reinforced lips or specialized designs that can handle the extra force.
The condition and speed of the shaft on which the oil seal will be mounted directly impact the seal’s performance. A worn or rough shaft surface can quickly damage the seal, leading to leakage.
- Shaft Surface: Ensure the shaft surface is smooth and free from grooves, scratches, or other imperfections that can compromise the seal. A polished shaft is ideal for maximizing the lifespan of the oil seal.
- Rotational Speed: Oil seals are designed to handle certain speeds. High-speed shafts require seals that can withstand the friction generated by rapid rotations without overheating or wearing out quickly.
If your application is exposed to harsh environmental conditions, dust, or debris, consider using double-lip or triple-lip skeleton oil seals. The extra lips provide additional protection, preventing contaminants from entering the system and compromising the lubrication.
For heavy-duty applications, seals with dust flingers or wipers may also be an option to keep contaminants at bay.
Some skeleton oil seals come with extra features designed to enhance performance and durability, especially in demanding applications. These include:
- Spring-Loaded Seals: Some seals feature a spring that helps maintain a tight fit around the shaft, ensuring consistent pressure and preventing leaks, even as the seal wears down over time.
- Labyrinth Seals: These seals have a unique design that provides extra resistance to contaminants, making them ideal for applications involving extreme dirt or dust exposure.
Finally, when choosing a skeleton oil seal, consider both the cost and the availability of spare parts. While it’s important not to compromise on quality, balance your budget with the specific needs of your application. Additionally, ensure that replacement seals are readily available for maintenance purposes.
Choosing the right skeleton oil seal involves understanding your application’s specific requirements, including the environment, shaft speed, pressure, and type of fluid being sealed. Consider the material, lip design, and seal size carefully, and ensure that the seal you select is suitable for the operating conditions. A high-quality, well-chosen skeleton oil seal will ensure efficient operation, extend the lifespan of your machinery, and reduce downtime due to leaks or failures.
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FOUNDED IN 1993
China SBT Oil Seal is an international company integrating design, research and development, production and processing.
No. 68, Hua'an Street, Renze District, Xingtai City, Hebei Province, China
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Won many honorary certificates through a number of patented inventions
