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The Functions And Types Of Bearing Seals


The functions of bearing seals

Bearing seals play a vital role in mechanical equipment, and their main functions are reflected in the following aspects:

  • Prevent grease leakage: The primary function of the bearing seal device is to ensure that the grease in the bearing does not leak due to factors such as pressure differences, temperature fluctuations or mechanical vibration. Lubricating grease is essential for the proper operation of bearings, not only reducing friction and wear, but also preventing bearings from overheating and damage. Therefore, an effective sealing device can ensure that the bearing is always well lubricated, thereby extending its service life.
  • Prevent the intrusion of external contaminants: The bearing seal device can also prevent external contaminants such as dust, moisture, chemicals, etc. from intruding into the inside of the bearing. These contaminants may cause deterioration of lubricating grease, corrosion of bearing surfaces, or increased wear, thereby affecting bearing performance and life. By blocking the entry of these contaminants, the seal keeps the inside of the bearing clean and dry, ensuring stable operation in harsh environments.
  • Maintain pressure balance inside the bearing: In some applications, bearings are required to withstand higher pressures. At this time, the sealing device can play a role in maintaining the pressure balance inside the bearing. By preventing internal pressure from being too high or too low, seals ensure that the bearings can function properly in high or low pressure environments, avoiding failure or damage caused by pressure fluctuations.


The types of bearing seals

Bearing seal devices can be mainly divided into three types: self-contained seal, external seal and hybrid seal. Each type has its specific design and application.

Comes with seal

Self-sealing means that the bearing itself is manufactured with a sealing performance device, such as a bearing with a dust cover, sealing ring, etc. This kind of seal takes up very little space, is easy to install and disassemble, and has a relatively low cost. The self-contained sealing device includes one or two contact or non-contact skeleton rubber seals, one or two dust covers, one skeleton rubber seal on one side and a dust cover on the other. They are often used to protect bearings from the intrusion of dust, moisture and other external contaminants while preventing the leakage of lubricating grease.

Additional seal

External seals are sealing devices with various properties that are manufactured inside the installation end cover, etc. External seals are divided into two types: non-contact and contact.

Non-contact seal: Non-contact seal device does not contact the bearing and does not produce friction. There are types such as oil groove, oil slinger and labyrinth seal. This form of seal generates almost no frictional heat and no wear during operation, and is especially suitable for high-speed and high-temperature applications. The non-contact sealing device can effectively prevent external contaminants from invading the inside of the bearing and prevent the leakage of lubricating grease.
Contact seal: The contact seal device uses the end of synthetic rubber, synthetic resin, felt and other materials to frictionally contact the rotating body to seal. They prevent the leakage of lubricating grease and the intrusion of external contaminants by closely contacting the bearings and rotating bodies.
When selecting an external seal, many factors need to be considered, such as the bearing lubricant and type, the working environment of the bearing, the supporting structural characteristics of the shaft, the circumferential speed of the sealing surface, the operating temperature of the bearing, and manufacturing costs.

Hybrid seal

In harsh environments such as dust and moisture, and in situations where lubricant leakage is not allowed, various sealing forms are often used in combination to achieve better sealing effects. Hybrid seals combine the advantages of self-contained seals and external seals, and provide a more comprehensive and reliable sealing effect by combining different types of sealing devices.