3/14
What are the commonly used hydraulic sealing materials
The sealing materials used for hydraulic cylinder seals in the sealing material market are generally synthetic rubber and synthetic resin. We are nitrile rubber (NBR), silicone rubber (VMQ), fluororubber (FKM), and ethylene propylene diene monomer (EPDM), which are materials with good sealing characteristics and can fully leverage their advantages.
Nitrile rubber (NBR): It is a widely used sealing material, and NBR seals have excellent oil resistance. Good wear resistance, air permeability, and oil resistance, suitable for mineral hydraulic oil, lubricating grease, silicone oil, flame retardant liquid, and 80 ℃ hot water. Not suitable for polar solvents and brake fluids. Ozone resistance and weather resistance are average, but they can be used as hydraulic cylinder seals and will not be affected by this.
Silicone rubber (VMQ): Seals have excellent resistance to high and low temperatures, and have a wide working temperature range among all rubber sealing materials; Excellent resistance to ozone, oxygen, light, weather, and aging. General silicone rubber has a certain resistance to low concentrations of acid and alkali, and also has good resistance to media such as ethanol and ketone; Special fluorosilicone rubber has excellent oil and solvent resistance.
Fluorine rubber (FKM): Its heat resistance is comparable to that of silicone rubber, and it can work for a long time at 250 ° C and withstand high temperatures of 300 ° C for a short time. One of the characteristics of fluororubber is its extremely superior corrosion resistance. It has stability and is superior to other types of rubber in terms of fuel oil, hydraulic oil, organic solvents, concentrated acids, strong bismuth agents, etc. However, its variety also varies. For example, in fuel oil, hydraulic cylinder oil, diester, silicate ester lubricating oil, boiling water and other media, the performance of Type 23 fluororubber is worse than that of Type 26 fluororubber in the environment. The additives in the formula also have an impact on the performance, such as peroxide vulcanization system products having better heat resistance to water than ammonia and phenolic vulcanization system products.
EPDM rubber: It has excellent sealing properties such as aging resistance, heat resistance, weather resistance, ozone resistance, and can withstand chemicals such as alcohols, acids, strong bases, and oxidants. However, it is not resistant to aliphatic and aromatic solvents. Therefore, it is not suitable for general mineral oil lubricating oils and hydraulic cylinder oils. The hydraulic cylinder seal product can be used for a long time in a 130 ° C environment, with higher temperatures up to 150 ℃ and lower temperatures up to 30 ℃.
