AARAV SEALS
ELASTOMERS
NITRILE-BUTADIENE RUBBER (NBR)
It is been recommended for the most part of the sealing elements applications and it has a very common use. Nitrile (NBR) is a Butadiene-Acrylo Nitrile (ACN) polymer. At Kastaş the percentage of Acrylo nitrile in the nitrile compound varies between 30% and 50%. The variation in the percentage of ACN changes the volume, gas permeability, elasticity and compression set of the compound used in mineral oils, grease and fuel. Nitrile is very durable against aliphatic hydrocarbons (i.e. propane, butane, petroleum, etc), mineral oils (lubricants, H, HL, HLP type of hydraulic oils), greases, HFA, HFB, HFC, vegetal-animal oils, light heating oil and diesel oil. For fuels and industrial fluids, different mixtures are prepared. Our standard nitrile compound is recommended to be used between 30°C, +105°C. For short period of time, it can be increased to +120 °C. With special additives to increase the lowest temperature resistance the nitrile compound can be used up to -40°C. The compression set of nitrile rubber is very good so it is been widely used as sealing elements.
HYDROGENATED NITRILE-BUTADIENE RUBBER (HNBR)
It is a kind of elastomer which is made in a way that a part or the complete part of NBR polymer is hydrogenised with double linked Butadiene. Vulcanized with peroxide, HNBR has durability against high temperature and oxidation. Having higher temperature resistance and mechanical properties than standard NBR compound, HNBR is recommended to be used between -30°C and 150°C. It has wide range of use especially in automotive sector and special applications in mobile hydraulics.
SILICONE (MVQ)
Silicone keeps its elasticity between -60°C and 200°C. It is not recommended to be used in dynamic applications. It has good resistance to ozone, air and grease. With special additives to increase the lowest temperature resistance MVQ compound can be used up to -90°C. It has less durability against oxidizing lubricants, some hipoits and lubricants of E.P. type.
FLUOROELASTOMER (FKM)
This material under the trademark Viton or Florel has less durability against all types of greases, lubricants and solvents. It has very good resistance against many chemicals. It gives good results in vacuum systems due to the low gas permeability. Mechanical properties and the temperature range can be improved with special additives. It has very low resistance to steam, hot water, methanol and other polar solvents. FKM can be used between -30°C and 225°C.
POLYCHLOROPRENE (CR)
This material under the trademark Neoprene has good resistance to rupture, tear and wearing out between the temperatures -45°C and 100°C. It has durability to flame. Its resistance against mineral oils with high aniline point, silicone oil, greases and alcohol is good. It is also being used in applications where durability for lubricants and atmospheric conditions are required.
POLYURETHANE (PU)
It is widely used in the sealing elements due to the improvements on the compression set property over the last 15 years. It has perfect durability against rupture, tear and wearing out between the temperatures -30°C and 100°C. Its resistance to mineral oils, grease and aliphatic hydrocarbon is good. Its resistance to polar solvents, aromatics, brake fluids, acid and alkaline is not very good. Especially, it is used as a shaft stripper and high pressurized sealing element.
ETHYLENE-PROPYLENE DIENE RUBBER (EPDM)
It can be used between the temperatures -40°C and 145°C. It has very good resistance to brake fluids, esther based lubricants, hot water and steam.
STYRENE BUTADIEN RUBBER (SBR)
Between the temperatures -50°C and 100°C, its resistance against glycol based brake fluids, inorganic/organic acids and alcohol is good.
NATURAL RUBBER (NR)
It is used between the temperatures -60°C and 100°C. It is recommended in applications where high flexibility is required.
THERMOPLASTICS
POLYTETRAFLUOROETHYLENE-PTFE
This material is known as Teflon, the trademark of DUPONT Company. PTFE material does have the lowest coefficient of friction. Due to the low friction coefficient and high wear resistance, it performs well on poorly lubricating conditions as well as high sliding speeds. PTFE can be used in temperatures between -200ËšC to +260ËšC. It has very good resistance to all chemicals except alkaline metals, high pressure-temperature chlorotriflour and basic flourines. Hardness and elasticity makethe material to be used widely in hydraulic applications.
Depending onto the application; glass, graphite, carbon, MoS2 and bronze filled PTFE can be used to increase mechanical and physical properties. The influence of the hydraulic media, the behavior in contact with the counter surface and the form stability depending on the operating temperature are the important properties when selecting the PTFE compound among the others. It is used between the temperatures -60°C and 100°C. It is recommended in applications where high flexibility is required.
POLYAMIDE-PA
This material is known as Nylon 6. It can be used in temperatures between -30°C to +120°C, for short period of applications this can
be increased up to +140°C. Polyamide is able to work on poorlylubricating conditions and does have high wear resistance. It is commonly used as guiding elements in hydraulic and pneumatic systems. Special additives can increase the mechanical and physical properties of the material depending on the application.
POLYOXYMETHYLENE - POLYACETAL (POM)
It has excellent form stability between temperatures -40°C to +100°C, for short period of applications this can be increase up to +140°C. It is commonly used as guide and backup rings in hydraulic and pneumatic systems. It is being safely used in mineral oils, HFA and HFB type of oils. For the guide ring, glass filled POM is used due to its high contact pressure value.
THERMOPLASTIC ELASTOMERS
THERMOPLASTIC POLYESTER ELASTOMER (TPE)
Polyester Elastomers are widely used as backup ring and header ring material with the sealing elements in hydraulic and pneumatic systems due to their chemical structure. It has excellent resistance to hydraulic oils and has high extrusion resistance compared to the other materials. It can be used in temperatures between -40°C to 120°C.
CHARACTERISTIC PROPERTIES OF RUBBER MATERIALS
