Oct. 13, 2023
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:
There are a variety of oil seals used in a variety of applications to help close the space between a stationary and a moving part. By closing the space it prevents any lubricants from escaping. Additionally, oil seals help create a seal that prevents any contaminants from entering machinery which can cause a host of problems. Mechanical equipment and machinery require different size or type oil seals to ensure that there is a superior and precise seal. Because oil seals help reduce contamination or mixing of materials it prolongs the life of machinery and helps ensure a more reliable performance.
There are a wide variety of industrial applications and therefore there are a wide variety of oil seals to meet the specific application needs. By choosing the right oil seal you will have a better fit, improved stability, and enhanced reliability. Rubber tends to be one of the most commonly used oil seal materials. SKF, an oil seal manufacturer, explains how oil seals for and the importance of proper installation, “To provide effective sealing, radial shaft seals must be installed properly. An experienced installer with suitable tools, working in a clean environment, is recommended to provide proper installation. The shaft counterface surface and housing bore should meet the demands specified in the sections Shaft requirements and Housing bore requirements. To facilitate seal installation and to achieve initial lubrication, prior to installation, SKF recommends wiping the shaft and seal with the lubricant that is going to be retained. While the outside diameter of metal-cased seals can be lightly lubricated to ease installation, the outside diameter of rubber covered seals should always be lubricated.
Seals with an auxiliary, contacting lip can also be filled with grease between the sealing lip and auxiliary lip to reduce frictional moment. This does not apply to silicone rubber seals and seals with hydrodynamic features, other than SKF WAVE lip designs. SKF also recommends using a hydraulic press, with suitable tools, to install a seal in its housing bore. Pressure should be applied as close as possible to the outside diameter of the seal.” Oil seals are commonly used in a variety of industries. Below are 5 types of oil seals used in today’s manufacturing and machinery industry.
5 Types of Oil Seals
Automotive
Industrial
Mechanical
Oil & Grease
Shaft
If you deal with rotatory shaft equipment, you would probably be having rubber seals in your mechanical assembly. For any manufacturing company, optimal functionality, efficiency, and long service life are essential to your success in the market. A component that is majorly underappreciated within a machine assembly, would be oil seal.
Shaft seals are used to prevent lubricant leaks like oil or grease and protect machinery from dirt, dust, and water—which makes them invaluable to industrial operations. In this post, we will dive deeper into oil seals and discuss everything that one must know, such as what it is, how it works, types, applications, and what to keep in mind when buying oil seals.
Rubber oil seals are placed between moving and static parts of mechanical equipment to prevent damage caused by moisture, contaminants, etc. Also known as rotatory shaft seals, grease seals, fluid seals, lip seals, and dirt seals; oil seals play an important role in closing the gaps between moving and stationary parts of machines.
Their main purpose is to retain or separate fluids from mixing and escaping the gauge, as well as stop moisture, abrasives, corrosive materials, and foreign contaminants from entering the parts, thereby ensuring maximum machine efficiency. Moreover, shaft rubber seals help prevent lubricant leakage at high pressure, for instance, when the machine is working at an extremely high pace.
Oil seals work by retaining lubricant in a thin layer between the lip and the shaft. These seals are attached to the bearing, with their lip pressing against the rotating shaft and the casing resting against the housing to hold the seal in place.
Oil seals perform some functions that ensure functionality at all costs and they do this by retaining lubricants at all costs and not making them escape no matter how high the pressure is. Whenever an oil seal fails, it creates seal leakage allowing abrasives, corrosive moistures and sediments to enter machines. Oil seals are especially used in equipment that has rotating, oscillating, and reciprocating shafts – pumps, pistons, etc.
Different types of seals offered by rubber products manufacturers in India include – Single and double lip oil seals, metal cased, external and internal oriented oil seals, and spring-energized oil seals and you can pick the one that best suits your industry requirements.
Practically, all machine equipment including assembled machines, car engines, and PTFE machined parts use these oil seals to prevent harmful interactions that could possibly result in damaged parts. They are used in the assembly of Elevators, conveyor belts, engines, grinding mills, pipelines, wind turbines, and more.
When equipment is under high pressure, lubricants tend to escape, and dry parts clash. Oil seals help prevent this by sealing holes where lubricants can leak out. rubber seals are designed to offer optimum sealing performance and extreme durability even under high-peripheral speed. They are lightweight, compact, and exhibit high self-lubricating properties. Oil seals are manufactured with high-grade materials and last long without showing any signs of hardening, softening, or aging.
Moreover, oil seals are widely used throughout the aerospace industry in both space exploration and aviation applications. Sujan Industries manufactures all aircraft rubber items including O-rings, Gaskets, Seals, Pistons, Grommets, Washers, and Protective Boots & Bellows. In the aviation sector, pneumatics and hydraulics are used to operate components like landing gear and wing flaps. Rubber gaskets are needed in these systems to keep dust and air out while ensuring aircraft components run effectively.
Picking the right type of oil seals is crucial for the proper functioning of machines because in some situations not all types can fit to work on certain machines.
There are quite a few factors to put into consideration when you’re choosing the right oil seal for your machine. Some of these factors include – dimensions, pressure, temperature, type of fluid, lubricant, shaft speed, shaft and bore tolerance, and more.
The capacity of oil seals to handle different intensities of pressure varies with their composition and application, so it is important to understand the compression set of your equipment. Just like the pressure, the temperature that your oil seal will be operating in must be known to be able to choose one that can withstand the working temperature.
Likewise, different types of fluids like grease, water, oil, fuels, etc. will come into contact with oil seals. So, knowing what type of fluids will be in constant contact with oil seals will help you choose the one capable of withstanding the surrounding conditions. When we talk about lubricants, seals always perform well when lubricated, however, in some machines there are dry spells. If you are a supplier of aftermarket parts in India or a user looking for oil seals in the aerospace industry, your search might end with Sujan Industries.
Oil seals are critical to a machine’s functionality. A machine’s oil seals are critical to its functionality. Picking the right seal for your machine is vital as it not only guarantees the optimum performance of applications but also ensures a safe working environment for years to come. With so many rotary shaft seal options available, it can be hard to know which one to choose for your machine! Contact us today to speak to one of our experts and pick the best one for you.
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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
