What material is the bearing seal made of?

Nitrile rubber

Nitrile rubber is a general-purpose sealing material. It is a rubber synthesized from acrylonitrile and butadiene and has good resistance to the following media.

Most mineral oils and mineral oil based greases

General fuels such as gasoline, diesel and light civilian fuels

Animal oil, vegetable oil and fat

Hot water

The nitrile rubber seal also allows the bearing to operate for a short period of time without oil. The permissible operating temperature range is -40 to 100 °C. It can withstand temperatures up to 120 ° C in a short time. However, it is not advisable to operate at higher temperatures because the nitrile rubber will harden.

Hydrogenated nitrile rubber

Hydrogenated nitrile rubber is more resistant to high temperatures than nitrile rubber, so seals made from this material have a longer working life. In addition, hydrogenated nitrile rubber has greater resistance to heat, ageing and hardening in hot oil or ozone. Hydrogenated nitrile rubber allows a maximum operating temperature of 150 ° C, which is much higher than the operating temperature of nitrile rubber.


The main characteristics of fluororubber are high temperature and chemical resistance, good anti-aging and ozone resistance, and very low gas permeability. Fluororubber still has excellent wear resistance even under very harsh working conditions. It can withstand operating temperatures of 200 ° C or below. Seals made of this material allow the bearings to run for a short period of time without oil.

Fluororubber also has excellent resistance to a wide range of media including oils and hydraulic oils, fuels, lubricants, mineral acids, aliphatic hydrocarbons and aromatic hydrocarbons. In the case of compounds such as esters, ethers, ketones, certain amines, and high temperature anhydrous hydrogen fluoride, fluororubber should not be used. If the seal made of fluororubber is exposed to an open flame or at a temperature above 300 °C, it will endanger health and the environment! They are dangerous even after cooling.


The role and characteristics of the seal

Seals are important for lubricant cleaning and bearing life.

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

The seal has the following characteristics:

Has sufficient deformability to compensate for irregular surfaces

Has enough strength to withstand the pressure at work

Able to withstand large operating temperature ranges

Chemical resistance

Minimal friction, frictional heat and wear during operation

Bearings with dust caps or seals on both sides are filled with grease and are generally maintenance-free.

Bearings with dust caps are suitable for applications in dry conditions and relatively clean working conditions. The dust cover is also suitable for applications requiring low friction, such as high speed or high temperature.

The dust cover is generally made of metal.

Bearings with contact seals are suitable for general contamination, applications where moisture or moisture is present, or require long service life and long-term maintenance-free conditions. The seals are generally made of rubber.

Reprinted from the network