Rubber materials

NBR? HNBR? Viton? FKM? MVQ? ...What material should I choose now?
In this article we summarise the most important things to know!

Choosing the correct rubber material is crucial in the field of sealing technology. Seals are components that prevent the flow of liquids or gases between two or more connected surfaces. Therefore, it is essential to select the appropriate rubber material for seals to ensure effective and reliable sealing.

The primary consideration in sealing technology is chemical compatibility. The materials, fluids, or gases present in a given environment or application can have different effects on rubber materials. For instance, if a seal is exposed to oils, acids, alkalis, or other aggressive substances, a rubber material must be chosen that can resist these chemicals without eroding or swelling.

The second important factor is operating temperature. Seals must withstand temperature fluctuations without compromising their properties or efficiency. Different rubber materials exist that are specifically designed to function effectively in high-temperature or low-temperature environments.

Other factors include pressure resistance, wear resistance, UV resistance, and weather resistance. Selecting the optimal rubber material takes into account these characteristics, ensuring long-lasting and reliable sealing performance.

In conclusion, choosing the correct rubber material is vital in sealing technology to achieve effective and reliable seals. Considering factors such as chemical compatibility, temperature resistance, and other properties enables the seals to function optimally and have a long service life.

The following table summarises the main types of materials and their main characteristics. Keeping these in mind will make it easier to choose.

NBR (Nitrile Butadiene Rubber) has excellent properties such as excellent oil resistance, fuel resistance, and abrasion resistance. It performs well at cold and moderate temperatures and generally has good sealing capabilities. However, NBR material is limited in its resistance to UV radiation, weathering, and ozone. It is not recommended for prolonged exposure to high temperatures or aggressive chemicals. NBR is commonly used in motor oil seals, gaskets, O-rings, and various industrial applications where oil resistance and fuel resistance are critical. The picture below shows a magnified image of an NBR o-ring exposed to ozone: the cracks are clearly visible. This is what happens with o-rings in a cheap garden sprinkler:

HNBR (Hydrogenated Nitrile Butadiene Rubber) is a rubber material that exhibits excellent properties. It possesses good chemical resistance against oils, fuels, and acids. It is fire-resistant and remains stable at high temperatures. HNBR offers exceptional wear resistance and flexibility, resulting in a long service life. It provides excellent sealing capabilities and withstands low and high pressures. It has good cold resistance, performing well at low temperatures. However, it has limited resistance to oxidizing acids and UV radiation. Additionally, it is relatively expensive and less readily available, which can be a disadvantage for users.

EPDM (ethylene propylene diene monomer) is an excellent rubber material with several advantages and a few limitations. EPDM stands out for its outstanding weather resistance, UV stability, and temperature resistance. It has good water resistance, chemical resistance, and satisfactory mechanical properties. However, EPDM has limited resistance to oils and greases and is not ideal for low-temperature applications. Additionally, its abrasion resistance is not as high as some other rubber materials. Overall, EPDM is an excellent choice for weather-resistant and chemical-resistant applications, but selecting the appropriate operating environment is important for achieving the best performance.

Viton is a fluororubber-based rubber material that has several advantages and a few limitations. Its good properties include excellent chemical resistance, high temperature tolerance, durability, and weather resistance. It is highly resistant to oils, acids, alkalis, and aggressive chemicals. However, Viton can be costly and has a relatively harder texture. Its low elasticity makes it more challenging to process and less suitable for applications requiring significant deformation. Overall, Viton is an excellent choice for those in need of high-level chemical and temperature resistance, but it comes with higher costs and limited flexibility.

Silicone rubber exhibits excellent heat resistance, weather resistance, and UV resistance. It has a wide range of chemical resistance. It is flexible and possesses excellent sealing and electrical insulation properties. It is easily processed and molded, and performs effectively over a wide temperature range. However, silicone rubber has low mechanical strength, limiting its use in high-load applications. It has a tendency to swell and bond with certain substances such as oils. Its adhesive properties are low, which can sometimes pose challenges for secure bonding.

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