Oil Seal Materials: NBR, FKM, PTFE, And More

✅ Nitrile Butadiene Rubber (NBR)

NBR is one of the most prevalently used materials for oil seals. It demonstrates excellent resistance to a wide array of oils and greases, such as mineral-based lubricants and hydraulic fluids. This makes it an ideal choice for automotive engines, gearboxes, and industrial machinery. NBR offers good mechanical properties and wear resistance, enhancing the durability of oil seals. However, its resistance to ozone, weather conditions, and high temperatures is somewhat limited. Generally, NBR-based oil seals are suitable for operating temperatures ranging from - 30°C to 120°C.

✅ Fluorocarbon Rubber (FKM)

FKM, a high-performance material, is renowned for its outstanding chemical and temperature resistance. It can endure a broad spectrum of chemicals, including oils, fuels, and solvents. FKM-made oil seals can function effectively at temperatures up to 250°C, making them suitable for applications in the aerospace, automotive, and chemical processing industries. For example, in aircraft engines, where extreme temperatures and harsh chemical environments are present, FKM oil seals ensure reliable performance. Despite its high-end properties, the relatively high cost of FKM might be a constraint in some applications.

✅ Polytetrafluoroethylene (PTFE)

PTFE is a material with unique characteristics. It has an extremely low coefficient of friction, which results in reduced wear and tear on the shaft and the seal itself. PTFE also exhibits remarkable chemical inertness, being resistant to almost all chemicals. It can operate across a wide temperature range, from as low as - 65°C to as high as 260°C. These features make PTFE an excellent choice for seals in chemical plants, high-temperature machinery, and pharmaceutical equipment. However, compared to some rubber-based materials, PTFE may require more precise installation and shaft surface finishing.

✅ Silicone Rubber (VMQ)

VMQ offers excellent flexibility over a wide temperature range, typically from - 60°C to 225°C. It maintains its elasticity even in cold conditions, which is crucial for applications where the seal needs to work effectively in low-temperature environments. Additionally, silicone rubber has good biocompatibility, making it suitable for use in medical devices and food-processing equipment. However, its mechanical strength and wear resistance are not as high as some other materials like NBR or FKM, restricting its use in high-wear applications.

✅ Ethylene - Propylene - Diene Monomer (EPDM)

EPDM is well-known for its outstanding weather resistance, ozone resistance, and water resistance. It is a great option for outdoor applications and environments involving water or steam, such as in HVAC systems, automotive cooling systems, and some parts of the plumbing industry. EPDM also shows good resistance to polar chemicals. Nevertheless, it is incompatible with petroleum-based oils and fuels, which limits its usage in oil-related applications.

✅ Acrylate Rubber (ACM)

ACM is highly resistant to heat, oil, and oxidation. It is particularly suitable for automotive applications, such as in transmission systems and power-steering systems, where it can withstand high-temperature conditions. However, ACM has limitations in terms of flexibility at low temperatures, and its resistance to acids and bases is relatively poor.

When choosing an oil-seal material, it is essential to comprehensively consider factors such as the operating temperature, the nature of the fluid being sealed, the pressure conditions, and the required service life. Each material has its own unique set of properties, and the right selection can significantly impact the performance and reliability of the oil-seal system.