Table of Contents

Oil Seal Buying Guide

Are you looking to keep your machinery free from 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 to select the right oil seal for your application.

Oil seals, also known as rotary shaft seals, fluid seals, or grease seals, play an important role in closing 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 uses these oil seals to remain free from harmful interactions that can cause serious and expensive damage to 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.

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.

Oil Seal Single Lip vs Double Lip

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.

Section 1: Understanding Oil Seals

Oil seals serve to close the gaps between stationary and moving components in machinery, preventing the escape of lubricants and the ingress of contaminants. These seals are crucial in maintaining the efficiency and longevity of equipment by protecting sensitive internal components from harmful interactions. Common applications include automotive engines, industrial equipment, and agricultural machinery.

Functions of Oil Seals

Preventing Leakage: Oil seals maintain the lubricant within the machinery, reducing wear and tear.
Contaminant Exclusion: They prevent dust, dirt, and other contaminants from entering the machinery.
Pressure Maintenance: Oil seals help maintain the internal pressure of machinery.

Common Applications

Automotive Engines: Keeping oil and other fluids in place within engines.
Industrial Equipment: Ensuring lubricants stay in place and contaminants stay out.
Agricultural Machinery: Protecting components from harsh environmental conditions.

Section 2: How Oil Seals are Made

The manufacturing process of oil seals involves several steps, ensuring they meet the required specifications for various applications.

Manufacturing Steps

Material Selection: Choosing the appropriate elastomer and metal components based on application requirements.
Molding: The elastomer is molded into the desired shape, often around a metal insert.
Vulcanization: The elastomer is vulcanized to enhance its mechanical properties.
Assembly: Components such as springs or reinforcing rings are assembled with the molded elastomer.
Quality Control: Each seal undergoes rigorous testing to ensure it meets performance standards.

Section 3: Types of Oil Seals

Rotary Shaft Seals

Rotary shaft seals, also known as radial shaft seals, are designed to seal the interface between a rotating shaft and a stationary housing. They are commonly used in automotive engines and industrial machinery.

Mechanical Face Seals

Mechanical face seals, or duo-cone seals, are used in heavy-duty applications such as construction and mining equipment. They consist of two precision-machined metal faces that form a dynamic seal.

Water Pump Seals

Water pump seals are specifically designed for water pump applications. They consist of stationary and rotating elements that create a watertight barrier.

Gland Packings

Gland packings are made from braided or twisted fibers such as PTFE, graphite, or aramid. They are used in high-temperature, high-pressure, and corrosive environments.

Common Types and Their Applications

Type	Application Area
Rotary Shaft Seals	Automotive, Industrial Machinery
Mechanical Face Seals	Mining, Construction Equipment
Water Pump Seals	Automotive Engines, Industrial Cooling Systems
Gland Packings	Pumps, Valves, High-Pressure Systems

Section 4: Oil Seal Materials

Different materials are used to manufacture oil seals, each suited for specific operational conditions. The choice of material depends on factors like temperature, pressure, and chemical exposure.

Nitrile (NBR)

Nitrile is known for its excellent resistance to oils and fuels, making it ideal for automotive and industrial applications.

Viton (FKM)

Viton offers high resistance to chemicals and extreme temperatures, making it suitable for aerospace and chemical processing industries.

Polyacrylate

Polyacrylate seals are used in automotive and transmission applications due to their resistance to oil, fuel, and environmental elements.

Silicone

Silicone seals provide high thermal resistance and flexibility, used in food processing and medical devices.

PTFE

PTFE seals are known for their exceptional chemical resistance and low friction, suitable for pharmaceutical and chemical industries.

Material Properties and Applications

Material	Properties	Applications
Nitrile	Oil/Fuel resistance, cost-effective	Automotive, Industrial Machinery
Viton	Chemical/Temperature resistance	Aerospace, Chemical Processing
Polyacrylate	Oil/Fuel/Environmental resistance	Automotive, Transmissions
Silicone	High Thermal resistance, flexible	Food Processing, Medical Devices
PTFE	Chemical resistance, low friction	Pharmaceutical, Chemical Industries

Section 5: How to Choose the Right Oil Seal

Choosing the right oil seal involves considering several key factors:

Pressure

Oil seals are designed for specific pressure ranges. Selecting a seal that can handle the operating pressure of your application is crucial.

Temperature

Consider the temperature range within which the oil seal will operate. Materials like PTFE and Viton can handle extreme temperatures.

Shaft Speed

The speed at which the shaft rotates affects the wear and performance of the oil seal. High-speed applications require seals with high lubricity and wear resistance.

Fluid Compatibility

Ensure the oil seal material is compatible with the fluids it will encounter, such as oils, fuels, or chemicals.

Lubrication

Oil seals perform best when properly lubricated. In cases of sparse lubrication, materials like PTFE or leather may be advantageous.

Selection Criteria

Criteria	Considerations
Pressure	Operating pressure range
Temperature	Operating temperature range
Shaft Speed	Speed of the rotating shaft
Fluid Type	Compatibility with oils, fuels, chemicals
Lubrication	Amount and type of lubrication

Section 6: Identifying and Measuring Oil Seals

Identifying Oil Seals

Oil seals can be identified by their design, size, and material. Common designs include single and double lip seals.

Single Lip vs. Double Lip

Single Lip: Primarily used to contain fluids within a system.
Double Lip: Provides additional protection against contaminants.

Measuring Oil Seals

Accurate measurement is crucial for selecting the correct oil seal. Measurements should include the inner diameter (ID), outer diameter (OD), and width (W).

Measurement Guidelines

Measurement	Description
Inner Diameter (ID)	Diameter of the shaft the seal fits around
Outer Diameter (OD)	Diameter of the seal’s outer edge
Width (W)	Thickness of the seal

Section 7: Common Oil Seal Designs

Type A – Rubber Covered Lip Seals

Fully covered in rubber, these seals offer excellent resistance to thermal cycling and chemicals.

Type B – Metal Outer Diameter Oil Seals

These economical seals have an exposed metal side, providing a closer fit between the seal and housing.

Type C – Reinforced Metal Insert Oil Seals

With an additional inner case, these seals offer greater structural rigidity for heavy-duty applications.

Type F – Stainless Steel Garter Spring

Similar to Type A, these seals include a corrosion-protected metal case and stainless-steel spring, suitable for a range of fuels and chemicals.

Design Types and Applications

Design Type	Description	Applications
Type A	Rubber covered, thermal/chemical resistant	General industrial, automotive
Type B	Metal outer diameter, economical	Automotive, light industrial
Type C	Reinforced metal insert, high rigidity	Heavy-duty industrial, construction
Type F	Stainless steel garter spring, corrosion resistant	Chemical processing, marine applications

Section 8: Top Oil Seal Manufacturers

Here are some of the top oil seal manufacturers, known for their high-quality products and innovation:

SKF Sealing Solutions

Website: SKF Sealing Solutions
Products: Wide range of seals including rotary shaft seals and hydraulic seals.

Trelleborg Sealing Solutions

Website: Trelleborg Sealing Solutions
Products: High-performance seals for various industries.

Freudenberg Sealing Technologies

Website: Freudenberg Sealing Technologies
Products: Innovative sealing solutions with a focus on sustainability.

NOK Corporation

Website: NOK Corporation
Products: Precision and durable oil seals for automotive and industrial machinery.

Parker Hannifin

Website: Parker Hannifin
Products: Comprehensive range of sealing solutions including oil seals.

EagleBurgmann

Website: EagleBurgmann
Products: Robust mechanical seals for heavy-duty applications.

John Crane

Website: John Crane
Products: Mechanical seals for critical applications in various industries.

TKS Sealing

Website: TKS Sealing
Products: Affordable and high-quality seals for automotive and industrial use.

Section 8: Top Oil Seal Manufacturers (Continued)

DMS Seals

Website: DMS Seals
Products: Comprehensive range of sealing solutions with advanced manufacturing techniques.

MyTech

Website: MyTech
Products: Sealing solutions with a focus on innovation and quality.

Wes offer a diverse range of oil seals designed to meet various industry requirements. Here is a product profile highlighting key features.

Materials

Nitrile (NBR): Excellent resistance to oils and fuels, suitable for automotive and industrial applications.
Viton (FKM): High resistance to chemicals and extreme temperatures, ideal for aerospace and chemical industries.
Silicone: High thermal resistance and flexibility, used in food processing and medical devices.
PTFE: Exceptional chemical resistance and low friction, suitable for pharmaceutical and chemical applications.

Types of Oil Seals

Rotary Shaft Seals: Designed to seal rotating shafts, preventing leakage and contamination.
Mechanical Face Seals: Robust seals for heavy-duty applications like mining and construction equipment.
Gland Packings: Used in high-temperature and high-pressure environments, such as in pumps and valves.

Design Features

Single Lip and Double Lip Seals: Single lip seals are used to retain fluids, while double lip seals also protect against contaminants.
Metal-Reinforced Seals: Provide structural integrity and improved fit for demanding applications.
Spring-Loaded Seals: Ensure consistent sealing pressure and enhanced durability.

Performance Attributes

High Temperature Resistance: Seals made from materials like Viton and PTFE can withstand extreme temperatures.
Chemical Resistance: Viton and PTFE seals offer superior resistance to aggressive chemicals.
Durability: Products from these manufacturers are designed to last, reducing maintenance and downtime.

Section 9: Installation and Maintenance of Oil Seals

Proper installation and maintenance of oil seals are crucial for ensuring their longevity and effective performance.

Installation Guidelines

Preparation: Clean the shaft and housing thoroughly to remove any debris or contaminants.
Lubrication: Apply a thin layer of lubricant to the seal to facilitate installation and reduce friction.
Alignment: Ensure the seal is aligned properly with the shaft and housing to prevent misalignment and uneven wear.
Pressing: Use a suitable tool to press the seal into place evenly, avoiding any deformation.

Maintenance Tips

Regular Inspections: Check seals periodically for signs of wear or damage.
Lubrication: Maintain appropriate levels of lubrication to reduce friction and wear.
Replacement: Replace seals promptly when signs of wear or damage are observed to prevent further issues.

Section 10: Troubleshooting Common Oil Seal Issues

Even with proper selection and maintenance, oil seals can encounter issues. Here are some common problems and their potential solutions:

Leakage

Cause: Misalignment, incorrect installation, or worn-out seal.
Solution: Reinstall the seal correctly, ensure proper alignment, and replace worn seals.

Contamination

Cause: Dirt or debris entering the seal.
Solution: Check and replace any damaged seals, ensure a clean environment during installation, and use double lip seals if necessary.

Wear and Tear

Cause: High friction, improper lubrication, or abrasive environment.
Solution: Ensure proper lubrication, use seals made from wear-resistant materials, and consider using protective covers or shields.

Section 11: Case Studies and Real-World Applications

Automotive Industry

Application: Oil seals are used extensively in engines, transmissions, and differentials to keep lubricants in and contaminants out.
Example: SKF Sealing Solutions provide high-performance seals that help improve fuel efficiency and reduce emissions in modern vehicles.

Industrial Machinery

Application: Oil seals in pumps, compressors, and gearboxes to maintain lubrication and prevent contamination.
Example: Trelleborg Sealing Solutions offers robust seals that enhance the reliability and longevity of industrial machinery.

Aerospace

Application: Seals in hydraulic systems, fuel systems, and engines to ensure safety and performance.
Example: Viton seals from Freudenberg are used in aerospace applications for their exceptional chemical and temperature resistance.

Section 12: Future Trends in Oil Seal Technology

The oil seal industry continues to evolve with advancements in materials and design to meet the growing demands of various industries.

Advanced Materials

Graphene-Enhanced Seals: Offering improved strength and durability.
Eco-Friendly Materials: Development of seals made from sustainable and biodegradable materials.

Smart Seals

Integrated Sensors: Seals with embedded sensors to monitor performance and predict failures.

Conclusion

Selecting the right oil seal is essential for maintaining the integrity and performance of your machinery. By considering factors such as pressure, temperature, shaft speed, fluid type, and lubrication, you can make informed decisions and ensure the longevity of your equipment. For more information or assistance, feel free to contact the top manufacturers listed in this guide.

References

By using this comprehensive guide, engineers and technicians can confidently select, install, and maintain oil seals to ensure optimal performance and reliability of their machinery.