May. 10, 2024
Oil seals are widely used as sealing devices for machines.
JTEKT's oil seals are described in our catalog, Oil Seals & O-Rings.
However, the catalog uses a large number of technical terms and is very long, so many people seem to have trouble handling it.
Therefore, this series of columns will summarize the following in order:
• The structure, functions, and types of oil seals
• How to select the right oil seal
• Handling of seals, and causes and countermeasures for oil seal failure
A wide range of sealing devices are used in various machines.
Sealing devices serve the following functions:
Prevent leakage of sealed lubricant from inside
Prevent entry of dust and foreign matter (dirt, water, metal powder, etc.) from outside
As shown in Figure 1, sealing devices come in two types: contact and non-contact.
Oil seals are among the major contact type sealing devices.
Figure 1: Types of sealing devices
Please see the following for the types of sealing devices for bearings.
How to Select the Right Bearing (Part 7): Components surrounding the bearing
Oil seals come in various shapes to fit the machines and substances to be sealed.
Figure 2 shows the structure and the names of the various components of the most typical oil seal.
The functions of the various components are also indicated in Table 1.
Figure 2: Typically shaped oil seal and component nomenclature
* "KOYO" is a registered trademark of JTEKT.
Table 1: The functions of the various components
No.
Name
Functions
①
Main lip The main lip is the most critical component of the seal.
Its sealing edge comes in full contact with the shaft surface in order to provide excellent sealing performance.
(See Figure 3.)
②
Minor lip The minor lip prevents the entry of dust and contaminants from outside.
Lubricant can be retained in the space between the main lip and the minor lip.
③
Sealing edge This refers to the component of the oil seal that makes contact with the shaft.
It is wedge-shaped to be pressed against the shaft surface and makes contact with the shaft to ensure sufficient sealing performance and suitability for operation at high peripheral speed.
④
Spring The spring supplements the tightening force (i.e., the lip radial load) to ensure enhanced sealing performance and tight contact between the shaft and the sealing edge.The spring also prevents the deterioration of main lip sealing performance caused by high heat or other such factors.
⑤
Metal case The metal case provides rigidity to the seal, helping it settle on the housing securely. It also ensures easy seal handling and mounting.
⑥
O.D. (outside diameter) surface The O.D. surface affixes the oil seal to the housing and prevents leakage , through the fitting area, of substances to be sealed, while excluding contaminants.
⑦
Fluid side face The front-end face of the seal is called the nose. The nose is made of rubber and forms a gasket seal when compressed on the housing shoulder.
⑧
Air side face The oil seal surface vertical to the center line of the shaft on the side that does not come in contact with substances to be sealed is called the back face.
Figure 3: Sealing function of main lip radial load
* "KOYO" is a registered trademark of JTEKT.
Figure 4 shows the features of a JTEKT oil seal.
Figure 4: JTEKT oil seal features
For more detailed information, please see the following:
Names and functions of seal components
Seals are classified by O.D. wall material, lip type, and whether they have a spring or not.
Major oil seals are specified in ISO 6194-1 and JIS B 2402-1.
Table 2 shows the common types of oil seals, while Table 3 shows the features of each type of oil seal.
Table 4 lists the JTEKT oil seal type codes and corresponding ISO and JIS standards.
Table 2 a): Common types of oil seals (with spring)
With spring Rubber O.D. wall Metal O.D. wall
Metal O.D. wall
(with a reinforcing inner metal case)
Without minor lip
Type code
With minor lip
Type code
Table 2 b): Common types of oil seals (without spring)
Without spring Rubber O.D. wall Metal O.D. wall
Without minor lip
Type code
With minor lip
Type code
Table 3: Features of each seal type
No.
Type
Features
1
With spring type Secures stable sealing performance.
2
Rubber O.D. wall type Provides stable sealing performance around the seal O.D. surface.
3
Metal O.D. wall type Ensures improved fitting retention between the seal O.D. and the housing bore.
4
Metal O.D. wall type (with a reinforcing inner metal case) Protects the main lip.
5
With minor lip type Used for applications where there are contaminants, such as dust and foreign matter, on the air side face of the oil seal.
Table 4: JTEKT oil seal type codes and corresponding ISO and JIS standards
JTEKT
ISO 6194-1 1)
JIS B 2402-1 2) MHS Type 1 HMS Type 2 HMSH Type 3 MH － HM － MHSA Type 4 HMSA Type 5 HMSAH Type 6 MHA － HMA －
Notes
1) ISO: International Organization for Standardization
2) 2) JIS: Japanese Industrial Standard
JTEKT provides special seals for use in a wide variety of machines and applications.
Table 5 lists the major special seals, their shapes, and their features.
Table 5: The major special seals, their shapes, and their features
Name Type
(type code) Shape Features
Helix Seal
The hydrodynamic ribsa) provided in one direction on the air side face of the lip ensure higher sealing performance. Perfect Seal The hydrodynamic ribsa) provided in two directions on the air side face of the lip ensure higher sealing performance (higher sealing performance in both rotational directions of the shaft).
Super Helix Seal
The hydrodynamic ribsa) have a two-stepped rib configuration provided in one direction on the air face of the lip. Even if the first rib is worn out, the second rib comes into contact with the shaft surface, meaning that this type of oil seal ensures higher sealing performance. Seal with Side Lip A large side lip ensures prevention of entry of dust/water.
a)
Function of hydrodynamic ribs
For more detailed information, please see the following:
Special seal types and their features
Figure 5 explains the JTEKT seal numbering system.
Seal numbers consist of
(1) the seal type code,
(2) the spring code,
(3) the lip type code,
(4) the dimensional numbers, and
(5) the special type code,
and Table 6 shows examples of each of these codes/numbers.
Figure 5: JTEKT seal numbering system
Table 6: Codes and numbers used in seal numbers
No. Code and number Example ① Seal type code (*)
MH: O.D. wall is a rubber material
HM: O.D. wall is a metal case
MH(S)H: O.D. wall is metal with a reinforced inner metal case
② Spring code
No code: without minor lip
A: with minor lip
③ Lip type code
No code: without minor lip
A: with minor lip
④ Dimensional numbers Shaft number 45: The seal suits the shaft diameter of ϕ45 mm. Housing bore number 70: The seal suits the housing bore diameter of ϕ70 mm. Width number 8: The seal width is 8 mm. ⑤ Special shape code
J: Additional code is added here as an identifier when two or more seals have exactly the same type codes and dimensional numbers.
Note: For seal type codes, see Table 2.
Oil seals are used in a great many machines.
Oil seals are used in many areas around the car.
Figure 6 shows the places where each seal type is used.
Figure 6: Oil seals for cars
For more detailed information, please see the following:
Oil seals for cars
Oil seals are used in a great many devices for steel production equipment.
Figure 7 shows the places where each seal type is used in a rolling mill.
Figure 7: Oil seals for steel production equipment (rolling mill)
For more detailed information, please see the following:
Oil seals for steel production equipment
Oil seals are one of the major contact type sealing devices.
• They prevent leakage of the lubricant or other sealed substance, and
• prevent entry of dust and foreign matter (dirt, water, metal powder, etc.) from outside.
Oil seals come in various shapes to fit the machine or substance for sealing.
For this reason, when designing a machine, it is important to select the oil seal that is right for that machine.
Next time, we will explain the key points to consider when selecting your oil seal.
If you have any technical questions regarding oil seals, or opinions/thoughts on these "Bearing Trivia" pages, please feel free to contact us using the following form:
Industrial seals
Dec 11, 2017
Several industrial equipment and machinery often consist of parts, whose one component is static and the other one is rotating. In such cases, there is a risk of creation of an opening between these two components, which can hamper the overall performance of the equipment. Industrial seals are mainly used for sealing this opening. This helps save considerably on the energy costs. Different types of high-quality seals are used in a wide range of industries. Thus, seals play a vital role in a number of industrial applications. Would you like to know the applications that use industrial seals? Please read the following post to know what all applications make use of industrial seals and how.
What are the Various Application Areas of Industrial Seals?
Industrial seals have a huge list of benefits, and this makes them ideal for use in a number of industries and applications. The following are some common application areas, which use industrial seals:
Textile Manufacturing: Various types of industrial seals are used in textile manufacturing industries. Some most commonly used types include mechanical seals, shaft seals, Teflon seals, and several others. High-performance polymers are used in the construction of these seals, which make them suitable for constant rotation of air rams, and compact spinning.
Die Casters: Die caster is an equipment, which is used for metal casting process. Industrial seals are also used in this application, in order to prevent any leakage, and provide proper sealing to the equipment.
Cheese Manufacturing: Yes, you read that right. Even the cheese manufacturing industry makes use of different types of industrial seals, in order to carry out the processes efficiently. Spring and energized seals, and pneumatic seals are some types of seals that are majorly used in this industry.
Farm & Agricultural Equipment: The farm and agricultural equipment are often exposed to UV rays, and various weather conditions. Thus, they may get contaminated from the surrounding things. The seals are used to protect these equipment from any potential harm. This helps increase their productivity. The single acting hydraulic seals are used in those equipment, which are used for tasks, such as harvesting, threshing, etc.
Printers in Publishing Industry: Several parts of machines used in the publishing industry are made from polyurethanes and rubber materials, which are capable of delivering high performance. The packaging machines and printing presses in the publishing industry use Teflon seals for a better performance.
Concrete Pumping: Specially designed seals are used in the concrete pumping equipment. This helps prevent the formation of dangerous blockages that may occur if the pump is not set properly.
Automobile Industry: Seals are used in vehicles, in order to prevent leakages. Seals made from sound absorbing materials, such as rubber and polyurethane are used in this industry. This helps in achieving compressed air savings.
These are just a few most common application areas of industrial seals. It won’t be wrong in saying that seals are among the most important components used in several applications in different industries. They are extremely crucial products, and thus should always be bought from trusted, experienced, and well-known manufacturers and suppliers. SSP Manufacturing, inc. is one such leading industrial seals manufacturer in the US.
At Global O-Ring and Seal, we understand the backbone of agriculture: machinery that works as hard as you do. In an industry where every second counts, your equipment’s performance is paramount. Activities such as tilling the soil, harvesting crops, and irrigating fields generate a blend of airborne particles, including soil, plant material, and other contaminants. When these particles penetrate the internal workings of machinery, they can lead to premature wear, decreased efficiency, and even equipment failure, resulting in significant costs for repairs and downtime.
Rotary seals are vital components for the agricultural sector’s smooth operation. Oil seals are particularly critical in tractors, which are often engineered with complex designs to bar the intrusion of harmful debris effectively. Additional sealing components like v-rings and gamma seals fortify this defense, providing an extra layer of protection against external pollutants.
The agricultural sector is a cornerstone of any economy, but it also brings its own unique sets of challenges, especially when it comes to machinery maintenance and sealing solutions.
Abrasion and Wear: The constant movement of soil, grains, and other abrasive materials can cause significant wear and tear on seals, requiring materials designed for high durability.
Harsh Environmental Conditions: Agriculture often involves outdoor operations exposed to the elements. O-Rings and seals need to be designed to withstand these conditions without degrading.
High Pressure: Farm machinery like tractors and harvesters often operate under high pressure, which can cause extrusion or deformation of seals if they are not adequately supported.
Chemical Exposure: Fertilizers, pesticides, and various soil treatments often come into contact with machinery. Seals need to be resistant to these chemicals to prevent breakdown and failure.
Vibration and Dynamic Loads: Machinery in agriculture is often subjected to varying levels of vibration and dynamic loads, which can cause seal displacement or failure if not properly designed.
Dush and Contaminants: Farming environments are often dusty or dirty, which can infiltrate machinery and cause seal failure if seals are not adequately designed to keep out such particles.
The following table provides a detailed overview of the seals commonly used in agriculture:
Seal Description Attributes Use Cases Nitrile O-Rings Made of synthetic rubber, ideal for applications that require resistance to oils and solvents. Resistant to oils, fuels, and water. Excellent durability. Used in tractor engines, hydraulic systems, and fuel handling equipment. Viton O-Rings Known for high chemical resistance and durability, made of fluoropolymer elastomer. High temperature and chemical resistance. Suitable for biodiesel engine systems, chemical sprayers, and high-temperature applications. EPDM O-Rings Ethylene Propylene Diene Monomer (EPDM) is great for outdoor applications due to weather resistance. UV, ozone, and weather resistant. Used in water pumps, irrigation systems, and outdoor machinery exposed to the elements. Square Rings Square-cut rings often used as an alternative to O-rings for static applications. Good stability, larger sealing surface area. Effective in static sealing where space allows, like flanges and manway covers. Backup Rings Used to prevent O-ring extrusion in high-pressure applications. Enhances the pressure resistance of primary seals. Often used in high-pressure hydraulic systems found in heavy-duty farming machinery. Oil Seals Seal off spaces between components in rotary and reciprocating motion applications. High wear resistance, good for high-speed applications. Used in rotating shafts in tractors, combines, and other heavy machinery. Fabric Reinforced Seals Composite seals designed for added strength and enhanced durability. Increased mechanical strength, greater wear resistance. Ideal for applications requiring extra durability like in grain and feed mixers. V-Rings Flexible, rubber seals that stretch-fit onto a shaft and rotate with it. Dust-proof, grease retention. Used in off-road vehicles and machines exposed to mud, water, and dust. Gamma Seals Sealing devices used to achieve leak-free connections. Highly adaptable and resilient, even in varying conditions. Used in irrigation systems and grain handling systems to prevent leaks. Shaft Repair Sleeves Used to repair worn-out shafts or protect new shafts. Cost-effective, reduces downtime. Commonly used in repairing agricultural machinery without requiring full shaft replacement. End Caps (Plugs) Used to block off the end of a line, usually in hydraulic or fuel systems. Easy to install, leak-proof. Used in hydraulic systems, temporary shutdowns or system tests.
The demanding conditions in the agriculture industry require specialized sealing solutions designed to withstand a wide range of challenges. At Global O-Ring and Seal, we understand these unique requirements. By offering a diverse range of products tailored for agricultural use, we aim to provide solutions that exceed the stringent demands of this critical sector.
Your success in agriculture is our commitment. Global O-Ring and Seal provides sealing solutions designed for the wear and tear of daily farming operations. For assistance, please give us a call at 832-753-6084 or fill out the Product Inquiry Form.
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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
+86 188 0309 4557
Won many honorary certificates through a number of patented inventions
