Gasket Gallery: NBR (Nitrile) Seals
Photo: automotive o-ring molded with blue NBR (Nitrile), shown to scale
Nitrile Butadiene Rubber (NBR), also known as Buna N, the “N” stands for acrylonitrile (ACN). The acrylonitrile segment of the molecular structure gives this material excellent tensile strength, abrasion resistance, and fuel/oil resistance. Increasing the ACN content can improve heat resistance and fuel impermeability.
This article includes a gallery of some of the NBR seals we manufacture in Mexico, followed by an explanation of key capabilities that help explain why we use NBR for automotive and industrial applications.
Nitrile outperforms other elastomers due to high tensile strength, including excellent abrasion, tear and compression set resistance. This material also has low resistance to ozone and sunlight and is not an ideal application where weathering is the primary consideration. NBR performs well in Petroleum oils and fuels, silicone oils and greases, Ethylene glycol, some acids, and water below 212F. Here are some of the characteristics that make it a good choice for the automotive and transportation seals we mold in Mexico:
1. Oil and Fuel Resistance: One of the most notable characteristics of NBR is its superior resistance to petroleum-based oils, fuels, and other hydrocarbons. This makes NBR an ideal material for gaskets in automotive engines, fuel systems, and industrial machinery, where exposure to these substances is common.
2. Thermal Stability: NBR offers good thermal stability, typically operating effectively in temperatures ranging from -40°C to +120°C. Special formulations can extend this range slightly higher, making NBR suitable for various thermal environments encountered in automotive and industrial applications.
3. Mechanical Strength: NBR is known for its good mechanical properties, including high tensile strength, abrasion resistance, and tear resistance. These attributes contribute to the durability and longevity of gaskets, enabling them to withstand the mechanical stresses of dynamic and static applications.
4. Flexibility and Elasticity: Despite its strength, NBR maintains flexibility and elasticity, allowing it to conform to different surfaces and maintain a tight seal. This is crucial for gaskets that need to adapt to slight imperfections in mating surfaces and accommodate thermal expansion and contraction.
5. Resistance to Wear and Compression Set: NBR gaskets exhibit good resistance to wear and a low compression set, meaning they can recover their original shape after being compressed. This property is essential for maintaining long-term sealing performance, especially in applications involving repeated pressure cycling.
6. Chemical Resistance: Beyond oil and fuel resistance, NBR also resists a variety of other chemicals, including certain acids and alkalis, though it is less resistant to weathering agents like ozone and UV radiation. For applications where ozone or UV exposure is significant, NBR gaskets may require additional protective measures or coatings.
To learn more about NBR, and other materials we use for molding automotive gaskets, visit our products page.
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FIFO raw material storage at our plant in Tijuana, Mexico