Everything You Need To Know About FKM Rubber

Look through any manufacturing industry today, and you’ll find that rubber plays a major part in what they do. Rubber has easily become one of the most versatile materials today, and as time goes on, there’s a sense that its application will only grow. 

Today, FKM rubber is amongst the most renowned and most functional types of rubber. And, many manufacturers have come to see the light and embrace it wholeheartedly. So, what is it, and why is it so popular? Let’s answer all these questions and more below.

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What Is FKM Rubber? 

To begin with, it is important to know that the “FKM” in “FKM rubber” stands for “Fluorocarbon.” So, whenever someone asks, “What does FKM stand for in rubbers?” it just means “Fluorocarbon rubber.”

Here, you have a type of synthetic rubber that is made from fluorinated hydrocarbon polymer. FKM rubber operates as what you call a “copolymer,” mixing with vinylidene fluoride (VDF) and hexafluoropropylene (HFP). you can also have a few FKM rubber compounds that contain the material’s reaction with other materials – a characteristic that makes FKM rubber especially flexible. 

Like many other synthetic rubbers, FKM rubber has a history dating back to about a century ago. With the First World War, industrialization kicked off hugely. And as a result, materials like rubber pretty much became the standard. This led to a massive development spree, with rubber being increasingly industrialized between the ‘30s and ‘50s. Soon enough, it was time for FKM rubber to take the stage. 

Fast forward a few decades later, and FKM fluoro rubber has pretty much become a staple in manufacturing and industrialized settings. 

The Properties Of FKM Rubber

FKM rubber is a truly peculiar material – especially among all other rubber variants. The material operates across different industries, and many manufacturers have been hopping on its bandwagon. 

But, besides just understanding what it is, there are specific characteristics that this material possesses, especially due to the intricate FKM rubber structure. Here is a look into some of these properties: 

The Physical Properties Of FKM Rubber 

It Resists A Broad Temperature Range 

One of the most significant properties of FKM rubber compounds is that they provide impressive levels of temperature resistance. Even when you place the material against temperatures that are higher than 200°C (392°F), you can count on FKM rubber to properly maintain its characteristics without any problems. 

It is Very Flexible

Every manufacturer wants a material that can work in different settings and pretty much conforms to what they want. This is another area where FKM rubber shines especially brightly. With its impressive build, the FKM rubber full form will be able to accommodate different shapes. 

As a result, the material works in different applications – perfect for today’s highly convoluted manufacturing industry and its needs. 

The Compression Set Is Low

If you take FKM rubber reinforced and compress it, you can rest assured that it will be able to go back to its original shape like nothing happened. The material’s low compression set is very notable – especially in applications where it will need to take a lot of contact. 

The Impressive Tensile Strength 

You will also notice that FKM rubber density comes with good tensile strength. Most rubbers have to work in situations where they come in contact with a lot of stress and strain, and FKM rubber remains durable through it all. 

This factor is joined by the material’s impressive resistance to general abrasion. Different FKM rubber grades have their levels of abrasion resistance, but you can generally find them on the high side. 

It Holds Its Elasticity 

When the material goes through considerable deformation, FKM rubber easily comes back to its original form. The material is especially heralded for its ability to seal, and this is one of the major reasons why. 

FKM Rubber’s Chemical Properties 

Its High Chemical Resistance 

FKM rubber has exhibited some impressively high levels of resistance to different chemicals. Whether it’s bases, acids, or other solvents, the material resists them, cutting off its reaction significantly. 

Weather Resistance Is High Too

It’s not just chemicals that FKM rubber resists – the material also does well to repel elements of the weather. So, if you need a rubber material that can work in outdoor conditions, this is a solid option for you.

Resistance To Water & Hydrolysis 

Another interesting characteristic of this material is that it resists any degradation caused by excessive exposure to steam and water. Just like the weather resistance factor, this means that FKM rubber will be able to work in wet environments. 

Stability With Fire & Heat

For this point, we’ll look at two major characteristics – flame and ozone resistance. With flame resistance, you can find specific FKM rubber compounds that will be able to hold their own when they come in contact with flame. And, with ozone resistance being another of the chemical properties of FKM rubber, you can count on the material being able to withstand exposure to the sun’s dangerous ultraviolet rays. 

Electrical Insulation

It is also worth noting that this material offers solid electrical insulation properties. This means that FKM rubber will be able to work in specific electrical instances where resistance to current is more than necessary.

Now, we should point out that these FKM rubber properties will depend primarily on the formulation and type of FKM rubber you’re working with. Nevertheless, it’s pretty safe to say that this is one impressive material overall. 

The Major Types & Classifications of FKM Rubber

Sifting through the different variants of the traditional rubber material can be challenging – especially if you’re a manufacturer. But, if you really want to get into the material’s specifics, then you would also need to be familiar with the rubber FKM types and classifications. 

As you can imagine, these FKM rubber grades have their specific characteristics and features. And, understanding them will be important if you want to make real good use of the FKM rubber full form.

Broad Rubber Classifications

FKM Rubber Dipolymers

 Probably the most prominent of the rubber FKM types are the Type A variants – also known as dipolymers. The fluorine content in FKM polymers is significantly lower than other types, and these materials come with high levels of low-temperature flexibility. Their chemical resistance is also a bit lower than most other variants, and this makes them especially perfect for making things like seals and O-rings.

Terpolymer FKM Rubbers

Next, we have the Type B variants – or, what experts refer to as terpolymers. With about 70% fluorine content, these materials have higher chemical resistance than their predecessors. When it comes to applications where exposed to harsh chemicals, the terpolymers are more than adequate to handle things.  

Classing FKM Rubber Based On Their Composition

Now that we have the two major categories, you also need to know that there are ways of classifying FKM rubber compounds based on what they contain – and, by extension, the properties of the materials in question. For this classification, we have the following options:

Fluorocarbon Rubber 

Whether it’s a Type A or Type B option, this is pretty much the generic term for elastomers that contain fluorine.  


Here, you have a considerably broader classification that covers different types of fluoroelastomers – of which FKM is a part. These elastomers come with a lot of fluorine in their general form, and they are quite versatile in how they work. 


Here, you have a type of FKM rubber that is made by The Chemours Company – a manufacturer that is quite notable in different circles. 

The Special FKM Rubber Grades

Finally, we should also mention some of the specialized FKM rubber compounds that have been formulated over the years. Some of these include:

High-Performance Grades

Developers have been able to make some formulations of FKM that especially hold their own in tough, extreme conditions. These could be higher temperatures, exposure to strong chemicals, and much more. 

Low-Temperature Grades

These types of FKM have higher levels of low-temperature flexibility, and they especially work when you need a rubber material that will hold onto its elastomeric properties at very low temperatures. 


Shortened as “FFKM,” this is a class of FKM rubber that takes chemical resistance to a new level. This variant has more fluorine atoms in its body, and you can use it in situations where the chemical content is higher and considerably more aggressive. 

Specialty Compounds

Then, we have the compounds that are built to fit into the use of specific industries – aeronautics, oil, and gas, you name it. 

How FKM Rubber Is Made

So, if you’re a material manufacturer looking to capitalize on FKM rubber, you might want to keep an eye out for how it is even made. In general, the gist of the matter is that FKM rubber formulation involves polymerizing different monomers to create the specific material you’re looking for. 

Now, different manufacturers tend to have their specific product formulations. But, at the end of the day, this is a bit of a breakdown of how the manufacturing process actually works: 

Synthesize The Monomer

In case you were wondering, Vinylidene Fluoride – or VDF, as some people might call it – is the main component in FKM rubber. It is a monomer that is obtained from combining acetylene and hydrogen fluoride. 

Manufacturers essentially combine this material with Hexafluoropropylene (HFP) and Tetrafluoroethylene (TFE), although there are FKM rubber formulations that might not necessarily need the latter. 

Go To Polymerization

Now that you have your monomer ready, you can polymerize it. 

For FKM rubber manufacturing, you usually have to go through a process known as copolymerization – here, you combine at least two monomers and form what is called a copolymer. 

The process can also involve the action of catalysts, initiators, and other components that essentially improve the speed and efficiency of the polymerization process. At the end of the day, you have an FKM polymer chain. 

Going Through Copolymerization 

For this process to work, it will need a lot of pressure and temperature. With this mix, the monomers will be able to react, forming the polymer structure you need and creating some of the FKM rubber characteristics that we already pointed out. 

 Some formulations of FKM will also include additional monomers like tetrafluoroethylene after the copolymerization process. This addition allows them to achieve some set characteristics. 

Adjusting The End-Group

Once the polymerization process is completed, the polymer’s end groups can be changed to also improve some of its properties. 

Material Compounding 

Next, you go on to compound the FKM polymer with different additives – accelerators, curing agents, etc. This process also helps the polymer to improve its physical properties and makes it more functional in the long run.

Process & Vulcanize Your Material 

The next step is to create the specific form of the compounded FKM – a sheet, a pellet, etc. Then, take it through vulcanization to ensure cross-linking in FKM rubber. Essentially, you add chemical agents and heat to the polymer and use those to optimize its chemical properties to a considerable degree. 

Test What You Have

Before you package your rubber, it’s important to test it as well. Thorough testing is needed to ensure that the rubber meets the specific standards and specifications you have for it.

What Are The Applications of FKM Rubber?

At the moment, FKM rubber is all the rage. Manufacturers love it for its flexibility, and the material itself is incredibly versatile. But, what is FKM rubber used for? Which industries can you find FKM rubber being used? Here is a breakdown of some of its most prominent uses: 

Seals & Gaskets For Cars

In the automotive industry, FKM rubber helps in making gaskets, O-rings, seals, and other components. This is because the material doesn’t react with fuel and engine oil, making it very perfect for working in engines and more. 

You can also see the material being used in making gaskets and seals for vehicle air conditioning systems – since these systems need to withstand high temperatures and refrigerant exposure. 

Use In Aerospace Functionalities

With its impressive temperature resistance levels, FKM is also a lock for aerospace functions. Like it is in the automotive space, the material helps in making gaskets, O-rings, and other important components that help airplanes function well. 

Oil and Gas & Chemical Processing

In both these fields, it is important to have materials that can resist chemicals, oils, and more. And, with its resistance to high temperatures, FKM rubber also works perfectly in aggressive environments. 

So, whether you want something to help make pumps, gaskets, or valves, FKM rubber is a solid material option. 

Making Electronic Components

Its electrical insulation means that FKM rubber can easily slot in when you need something to make electronic components, such as a watch, or watch strap 22mm, 21mm, 20mm, 19mm, 18mm. Color available like white, black etc. Also available in short and large sizes, you can chose what is the best for your needs. Beside that devices that need to properly manage heat and chemicals can use FKM to make seals and gaskets. 

Drugs & Food Manufacturing

In both the food and pharmaceutical spaces, FKM rubber also works. The material is compliant with regulations, and its resistance to the chemicals in cleaning agents makes it an especially solid option overall. 

Developing Medical Tools

Some specific formulations of FKM also meet regulatory requirements for use in developing medical devices. These formulations are biocompatible, and their resistance to the entire sterilization process makes them perfect for use in the medical field. 

Mining Tools

Among the FKM rubber applications, we should also point out its use in mining. 

You see, mining equipment needs to be exposed to some truly harsh conditions. Fortunately, FKM is up to the task, ensuring that these tools can be protected overall.

What Are FKM Rubber’s Advantages & Setbacks?

FKM synthetic rubber has continued to be a blazing material across the board. And with so many options and variations available, the material remains a favorite among many manufacturers.

Below, we’ll look at a few areas where FKM rubber shines, as well as a few other areas where the material might need a little bit of work: 

Advantages & Benefits 

FKM Rubber Resists A Lot Of impurities

Where do you want to start? Chemical resistance? High temperature resistance? Resistance to fuel and oils? FKM rubber exhibits all of this and much more. This broad resistance makes FKM rubber perfect for working in environments where you need a rigid, strong material to work. 

Whether you have a strong mechanical need or you want a material that can work in broad daylight, rest assured that FKm composite rubber will be there to help out. 

The Low Compression Set Solidifies Its Characteristics

FKM rubber’s low compression set also means that the material can hold its shape and considerable properties even after you’ve compressed it significantly. For sealing tasks, this is especially important in ensuring that FKm rubber remains useful. 

It Is Very Flexible 

Elasticity is one area where FKM rubber shines rather well. You can mold it into different shapes and forms, and you can rest assured that it’ll hold its shape over time.

Some Formulations Are Perfect For Human Contact 

Specific formulations of FKM rubber are biocompatible. This makes them perfect for use in pharmaceutical devices or medical applications. 

Challenges & Setbacks 

It Can Be Expensive 

For manufacturers who follow a strict budget, FKM rubber can be a very expensive product option. Its benefits are considerable, but the price requirement should definitely not be overlooked. 

Flexibility In Low Temperatures Isn’t So Much 

FKM rubber generally doesn’t exhibit much in terms of flexibility when temperatures are low. If you need a material that works in extremely low conditions, then you might need to get an alternative instead. 

Performance Isn’t Necessarily Uniform

You might also notice that FKM vulcanized rubber has an overall performance that isn’t necessarily consistent. It varies based on the formulation you’re working with, as well as the company making the material itself. So, before choosing which variation to work with, you need to be very careful and consider your requirements. 

FKM Rubber vs Silicone

FKM rubber has a tensile strength of 10 MPa, higher than silicone, making it an ideal choice for high-force, high-pressure applications.


Today, FKM rubber has grown to become one of the most popular rubber variants in the world. And, it’s easy to see why it is so prominent. 

As long as you understand what you’re looking for and the specific formulation that can deliver these benefits, you should be more than good to go.  

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