FFKM and FKM elastomers: a deep dive into their unique strengths

FKM and FFKM belong to the family of highly resistant fluorinated elastomers, capable of withstanding extreme temperatures and the most aggressive chemicals. They have many similarities, but what distinguishes them? When should you choose one over the other?

FKM (Fluoroelastomer)

A compound with excellent resistance to high temperatures and chemical attack, usable at temperatures ranging from -20°C to +210°C, and up to +230°C for short periods. With specific formulations, the low-temperature limit can extend to -45°C (TR10).

• Excellent compatibility with mineral and synthetic hydraulic fluids and vegetable oils.
• Limited resistance to hot water and steam (though specific formulations are available that enhance performance in this environment).
• Good resistance to environmental agents (ozone, UV rays). Low gas permeability and poor electrical insulation properties.
• Not compatible with polar solvents, certain organic acids, ester-based hydraulic fluids, methanol, ammonia, and some amines.
• Compatible with high-energy radiation (up to approximately 100 Rads).

FKM materials can be vulcanized with bisphenols, providing better high-temperature performance, or with peroxides, offering better resistance to steam and hydrocarbons.

The base polymers used for compounding include:

Copolymers

1. Fluorine content: 65% / 66%
2. Typically labeled with the letter “A”
3. Commonly used in general applications.

Terpolymers

1. Fluorine content: 66.5% / 67%
2. Typically labeled with the letter “B”
3. Offer better resistance to fluids and oils than copolymers.

Oringone offers a wide selection of FKM materials in various colors and hardness levels (60 to 90 Shore A), certified according to FDA, USP, 3-A Sanitary, and RGD standards for the Oil & Gas industry.

FFKM

Perfluoroelastomers (FFKM) are the most resistant elastomeric materials on the market, withstanding high temperatures (up to 325°C) and chemical aggressors. FFKM Eztra® materials ensure top performance in critical sealing applications where high temperatures, chemical aggressiveness, and long-term sealing reliability are crucial:

• Chemical Resistance: Nearly universal chemical resistance, including polar solvents, strong acids and bases, and other extreme chemicals.
• Thermal Resistance: Capable of withstanding much higher temperatures than FKM, often up to 300°C, with peaks of 325°C. It can also withstand low temperatures down to -40°C.
• High Compatibility: Excellent resistance to gas and liquid permeation, as well as outstanding resistance to weathering and ozone.

Our FFKM O-rings are divided into four families:

1. HT: High-temperature materials
2. CH: Materials for chemically aggressive environments
3. LT: Materials for low-temperature applications
4. FB+M: Materials for food, beverage, and medical applications

The combination of our CO.SM.O. compression molding system with the new EZTRAfactory allows us to offer the most extensive range of FFKM-Eztra® O-rings on the market, from the smallest diameter of 0.74 mm to diameters spanning several meters, all fully customizable.