Nitrile rubber:

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

Most mineral oils and greases based on mineral oils

General fuels such as gasoline, diesel and light domestic fuels

Animal and vegetable oils and fats

hot water

Nitrile rubber seals also allow the bearing to operate for short periods of time without oil. The allowable operating temperature range is -40 to 100°C. It can withstand temperatures up to 120°C for a short period of time. But it is not suitable for operation at higher and 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 an increasingly long operating life. In addition, hydrogenated nitrile rubber has stronger and stronger resistance to heat, aging and hardening in hot oil or ozone. Hydrogenated nitrile rubber allows a maximum working temperature of 150 ° C, which is much higher than that of nitrile rubber.

 

 

fluororubber

The most important characteristics of fluororubber are high temperature resistance and chemical corrosion resistance, and it has very good anti-aging and anti-ozone properties, so the air permeability is also very low. Even under very harsh working conditions, fluoroelastomers still have excellent wear resistance. It can withstand operating temperatures of 200°C or below. Seals made of this material allow the bearing to operate without oil for short periods of time.

Fluoroelastomers also have excellent resistance to a variety of media including oils and hydraulic oils, fuel oils, lubricants, inorganic acids, aliphatic and aromatic hydrocarbons, and more. Fluoroelastomers should never be used in the presence of compounds such as esters, ethers, ketones, certain amines and high temperature anhydrous hydrogen fluoride. If seals made of fluororubber are exposed to open flames or to high temperatures exceeding 300°C, it will endanger health and the environment! They are dangerous even after cooling.

 

The role and characteristics of seals

Seals are important for lubricant cleanliness and bearing life.

The function of the seal is to prevent the loss of lubricant and the ingress of contaminants into the space to be protected.

 

Seals have the following properties:

Sufficient deformability to compensate for irregular surfaces

Strong enough to withstand the stress of work

Able to withstand a relatively large operating temperature range

 

chemical resistance

Operation with minimal friction, frictional heat and wear

Bearings with dust caps or seals on both sides are already filled with grease and generally require no maintenance.

Bearings with shields are suitable for applications in dry and fairly clean operating conditions. Dust caps are also suitable for applications requiring low friction, such as high speeds or high temperatures.

The dust cover is generally made of metal.

Bearings with contact seals are suitable for applications with moderate levels of contamination and the presence of moisture or humidity, or where a relatively long service life and years of maintenance-free are required. Seals are generally made of rubber.