Understanding Sealing in Bearings

🔗 Mechanical transmission

Date of publication : 02/08/2023

Reading time : 4 Minutes


Seals have a decisive influence on system performance. By choosing the right sealing solutions, you can have an impact on the capacity, longevity and performance of your equipment.

Seals have a decisive influence on system performance. By choosing the right sealing solutions, you can impact the capacity, longevity and performance of your equipment by reducing friction, extending service intervals and increasing durability all at the same time. With a seal by their side, our bearings And our levels are unbeatable.

Seals and their role

Gaskets are components used to prevent the leakage of fluids, liquids or gases, between two mating surfaces. Their main purpose is to create an airtight barrier that prevents liquids from getting lost or entering undesirably.

These seals are required in many industrial and domestic applications to ensure the integrity of systems and equipment. They are used in industries such as automotive, aerospace, power, oil and gas, pipelines, etc.

Gaskets are made from different materials depending on the specific requirements of each application. Commonly used materials are rubber, silicone, plastic, metal and composite materials. These materials are chosen for their flexibility, fluid resistance, heat resistance and durability.

Several pads are available for different configurations and operating conditions. The most common are static and dynamic seals. Static seals are used when the connected parts do not move relative to each other, such as flanged joints. Dynamic seals are designed to seal moving surfaces such as engine piston seals or valve seals.

Gaskets are essential to maintain system integrity and prevent leaks. They guarantee the safety, performance and durability of the devices. For example, in the oil and gas industry, sealants are used to seal pipes and valves to prevent potentially dangerous leaks. In the automotive industry, gaskets seal engines, fuel systems and air conditioners.

Seals with DD-DDU type contact

These seals are typically feature a rubber lip or similar material that contacts the inner race of the bearing to provide a seal against outside contaminants. They also retain grease inside the bearing for effective lubrication. These gaskets provide a good dust and liquid seal and are commonly used in applications where protection from contaminants is essential.

Rubber: Rubber is the most commonly used material for lip seals. It offers good resistance to oil, fuels and chemicals, making it ideal for many industrial applications.

Fluorocarbures (FKM/Viton) : FKM gaskets offer superior chemical resistance, excellent high temperature resistance and low gas permeability. They are often used in environments where nitrile rubber would not be adequate.

Joints sans contact type VV 

These seals are designed to provide a frictionless seal around the bearing. They usually feature seals made of nitrile rubber or a similar material that does not come into direct contact with the inner ring of the bearing. These seals are suitable for applications requiring high speeds, as they minimize friction. Although they provide a good dust seal, they do not trap grease inside the bearing and are not designed for complete liquid sealing.

Rubber : Nitrile rubber is also commonly used in non-contact seals for its liquid and dust sealing properties.

Steel : Steel is often used to reinforce and stabilize rubber gaskets in non-contact joints, providing better mechanical strength.

Joints type ZZ 

These seals consist of metal flanges that surround the bearing without direct contact with the inner ring. They act as a physical barrier against solid contaminants such as dust and debris. Shielded metal seals provide a high dust seal but generally do not retain grease inside the bearing. They are commonly used in applications where protection against solid particles is essential, but resistance to liquids is not paramount.

Steel : Shielded metal gaskets are usually made from steel, which makes them sturdy and able to effectively shield against solid particles and contaminants.

Interchangeability of our bearings

Interchangeability in bearings refers to the ability to replace a defective or worn bearing with another equivalent bearing, either from the same manufacturer or from a different manufacturer, but having the same specifications and dimensions. The purpose of interchangeability is to facilitate the maintenance and replacement of bearings in machinery and equipment without the need for changing designs or adjustments.

When a bearing requires replacement, it is essential to find a replacement that is perfect for the specific application.The main bearing interchangeability criteria are as follows:

The importance of seals on bearing life

Bearings are important mechanical components used in many industrial and engineering applications, from machine tools to vehicles and industrial equipment. To ensure their proper functioning and durability, it is very important to protect these valuable components from the harmful effects of dirt and debris. In this article, we will explore the positive effects of oil seals on bearings and why they are so important to bearing life.

Protection against contaminants

  • One of the most important functions of seals is to protect bearings from external contaminants. Imagine an industrial environment where dust, dirt, debris and moisture can easily enter an unprotected bearing. These contaminants can cause premature wear of bearing surfaces, break down the grease film and potentially cause bearing failure. The seals act as an effective barrier against these damaging elements, keeping the inside of the bearing clean and in good condition.

Lubricant preservation

  • Proper lubrication is essential to reduce internal friction and minimize bearing wear. However, if the lubricant leaks from the bearing, either due to splashing or evaporation, it can lead to insufficient lubrication and increased friction between moving parts. Seals play a key role in keeping lubricant inside the bearing, providing a continuous film of lubrication to reduce friction and prevent damage caused by insufficient lubrication.

Reduced friction and heat

  • If the bearing surfaces are well lubricated and protected from contamination, the seals help reduce friction between the moving parts of the bearing. This results in less heat buildup in the bearing, which is necessary to prevent potentially damaging overheating. Controlled temperature helps extend the life of bearing components and ensures more efficient operation of the entire system.

Longer life and lower maintenance costs

  • By protecting bearings from contamination, retaining lubricant and reducing friction, seals directly extend bearing life. Well-maintained bearings require less frequent replacement, helping to reduce maintenance costs and downtime in critical industrial applications. Seals are therefore a necessary element to improve the reliability and profitability of mechanical systems.


Seals play an important role in the durability and performance of bearings. By protecting against contaminants, retaining lubricant, reducing friction and extending life, these small parts play an important role in industrial and mechanical operations. By choosing the right type of seal for each application, the reliability, efficiency and durability of bearings can be dramatically improved, helping to keep critical systems running smoothly in a variety of industries.

To note : To benefit from personalized expertise and deepen your knowledge of our products, we strongly encourage you to visit our premises or contact our product specialists.

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