The plastic type PEEK (poly-ether-ether-ketone) is a popular and widely used material. And with good reason, as it has exceptional thermal stability and superior mechanical properties. In this article, we take a closer look at exactly what PEEK is and what makes it so unique. One of our PEEK experts, Ron van de Ruit, talks about the various properties and applications of this plastic.
PEEK is a high-performance polymer in the family of polyaryletherketone. The material was developed in the 1970s by a team of researchers at the British company ICI. They were looking for a chemically resistant and heat-resistant polymer with good mechanical properties. They managed to synthesise it and originally named it PEEK-3810. The number 3810 referred to the desired viscosity of the polymer. This is now omitted and the material is simply referred to as PEEK.
PEEK is considered one of the best performing thermoplastics in the world. Like the better-known material PTFE, it has a low friction coefficient, low moisture absorption and high chemical resistance. Additionally, PEEK contains two other unique properties:
One of the main characteristics of PEEK is its high melting temperature. PEEK melts at around 250°C and in short bursts not until 310°C. This makes the material resistant to extreme temperatures.
PEEK has excellent mechanical properties, including high stiffness, toughness and abrasion resistance. This plastic can withstand high loads and does not easily warp under pressure.
It is possible to add additives to PEEK to change its properties. For example, you can add carbon to make the material even stronger. It then also becomes electrically conductive, so the electrical insulation that plastic has by nature is eliminated when adding carbon. Ron says: “If this is not desired, the solution is to add glass. This also reinforces. So if you want to reinforce PEEK, adding carbon would be the first option. But if it has to insulate, choose glass instead.”
Another option is to add graphite, carbon and PTFE. This makes the material smoother and stronger. This is ideal for plain bearings, for example, that require high temperature resistance and are subjected to a lot of pressure.
When PEEK entered the market, it was initially used primarily in the aerospace industry due to its heat resistance and strength. Later, it was also adopted by the medical industry due to its bio-compatibility and capacity to be sterilised. Today, PEEK is used worldwide in a variety of industries, including the automotive and electronics industries. At Polyfluor, we mostly make smaller parts from PEEK, such as bearings and gears. But larger applications are certainly also possible!
PEEK is more expensive to produce than PTFE, for example. The raw material is more expensive and the processing is more complicated. Therefore, PEEK is chosen only if the specific application requires PEEK's unique properties. “PEEK, unlike PTFE, is pressed at a high temperature and then becomes very fluid and sticky. For this reason, it requires casting a special high-end steel die. If this die is used frequently, then it is well worth it. But you can imagine that for one-time use, it quickly becomes too expensive,” Ron says.
Ron also says that for complex parts, injection moulding can be a convenient solution. “Injection moulding is not possible for all types of plastics, but it is possible for PEEK. Especially for large quantities, PEEK is a very good option.”
We are happy to give you some input. At Polyfluor, we help you put together the right material for the application you have in mind. Do you want to know more about PTFE or request a quotation? Then please feel free to contact us.