On both ends of rolling bearings, corresponding sealing devices are installed. There are two types with different performances: one with a dust cover and the other with a sealing ring, one for dust protection and the other for sealing. So, what are the common materials for these sealing devices? The main types are as follows:

• Nitrile Rubber: Nitrile rubber is a universal sealing material, made from acrylonitrile and butadiene. It has good resistance to the following media: most mineral oils and mineral oil-based greases, general fuels such as gasoline, diesel, and light domestic heating oil, animal oils, vegetable oils and fats, hot water. Nitrile rubber seals also allow bearings to run for a short time without oil. The permissible operating temperature range is -40 to 100°C, and it can withstand temperatures up to 120°C for a short period. However, it should not operate at higher temperatures as nitrile rubber will harden.

• Hydrogenated Nitrile Rubber: Hydrogenated nitrile rubber has better wear resistance than nitrile rubber, so seals made of this material have a longer service life. In addition, hydrogenated nitrile rubber has stronger heat resistance, aging resistance, and hardening resistance in hot oil or ozone. The maximum operating temperature for hydrogenated nitrile rubber is 150°C, much higher than that of nitrile rubber.

• Fluororubber: Fluororubber's main characteristics are high-temperature resistance and chemical corrosion resistance, with excellent aging and ozone resistance, and very low gas permeability. Even under very harsh working conditions, fluororubber still has excellent wear resistance. It can withstand working temperatures of 200°C or below. Seals made of this material allow bearings to run for a short time without oil. However, fluororubber should not be used in the presence of esters, ethers, ketones, certain amines, and anhydrous hydrogen fluoride at high temperatures. If fluororubber seals are exposed to open flames or temperatures above 300°C, they can be hazardous to health and the environment! Even after cooling, they pose a danger.

The role of seals is to prevent the loss of lubricant and to prevent contaminants from entering the space to be protected.

Characteristics of Bearing Seal Devices:

• Sufficient deformation ability to compensate for irregular surfaces.
• Sufficient strength to withstand the pressure during operation.
• Ability to withstand a wide range of operating temperatures.