PEEK, or polyether ether ketone, is a semi-crystalline thermoplastic and forms the absolute top of the high-performance plastic pyramid. PEEK was introduced to the market in 1979 by Imperial Chemical Industries, which was dissolved in 2007, and was initially mainly processed using the injection moulding process.
For a long time, the use of this high-performance plastic was associated with major difficulties for additive manufacturing. As PEEK has a very high temperature resistance, extruder temperatures of over 350 °C are required to be able to process a PEEK filament at all. At the same time, the building board temperature must be above 230 °C in order to obtain components without deformation.
However, these increased temperatures alone are not enough - temperature fluctuations must be avoided throughout the entire printing process. A printer is therefore required that can not only reach very high temperatures but also maintain them at a constant level.
Even today, filament 3D printers with these properties are as rare as white ravens. However, with the ARGO series from the Italian manufacturer Roboze, we have one of these white ravens in our service portfolio and can therefore report first-hand on the many advantages that 3D-printed components made of PEEK offer.
In this blog post, I will characterise the features that make up PEEK components and name the ideal areas of application that result from these features. So let's start right away with the first feature.
Heat resistance
Although the aforementioned feature of PEEK's high heat resistance makes the material difficult to process, it is a brilliant safety guarantor in use. Even at perpetual temperatures of up to 250 °C, PEEK filament retains its mechanical properties and melting only occurs at approx. 334 °C.
This makes PEEK the perfect material for high-temperature applications. It ensures risk-free operation of, for example, aerospace components, automotive components, both for passenger vehicles and in motor sports, and electronic components, where the heat-related failure of components would not only harm the machines, but also the people who operate them.
Dielectric properties
PEEK is a good dielectric with a dielectric strength of 20 kV/mm, a permittivity, i.e. polarization capacity, of 3.1 and a dissipation factor of 0.004. This means that PEEK hardly conducts electricity, but at the same time enables an electrostatic field to be maintained - a combination that very few materials can offer.
As a result, PEEK is increasingly being used as an insulator. The good dielectric properties in combination with the outstanding mechanical characteristics enable it to be used as an insulator in high-voltage technology and power supply cables, but also as a wafer carrier in semiconductor technology.
Tensile strength
The tensile strength of PEEK is another property that makes the material a high-performance plastic. With a value of up to 110 MPa, PEEK far exceeds the vast majority of filaments, whose values are usually between 50 and 80 MPa. PEEK even outperforms some non-ferrous alloys with this value.
Tensile strength is required in many industrial applications. The automotive and aerospace industries in particular benefit from the high tensile strength of structural components made from PEEK.
Lightweight
PEEK offers all its properties at a very low weight. The average density of PEEK is 1.3 g/cm³, which is lower than even lightweight aluminum alloys, which have an average density of 2.8 g/cm³.
This light weight in combination with the excellent mechanical properties make it an ideal replacement for cost-intensive and often very heavy metal components in order to make means of transportation lighter and therefore more energy-efficient.
Chemical resistance
Resistance to a wide range of chemicals is essential in many applications - and with PEEK, this resistance is more than just fulfilled. PEEK is resistant to the vast majority of organic and inorganic chemicals. The only major exceptions are hydrochlorides, highly concentrated nitric and sulphuric acid and some halogenated and aliphatic hydrocarbons.
This far-reaching chemical resistance means the chemical industry can breathe a sigh of relief. While many other materials with similar resistance are weaker in terms of mechanical or thermal properties, PEEK forms an ideal symbiosis of these characteristics to provide ideal components for chemically demanding applications.
Biocompatibility
People themselves also benefit from the use of PEEK. PEEK is safe for contact with human skin and mucosa and can also be repeatedly sterilized, is resistant to electromagnetic waves, e.g. gamma and X-rays, and has durable, bone-like mechanical properties.
As a result, PEEK is used in many different ways in medical technology. Both medical instruments and implants of various kinds, from the spine to the thorax to the skull cap, are now not only possible with 3D printing in combination with PEEK, but are already a reality.
Low outgassing rate
Last but not least, a more specific advantage, namely for applications in the ultra-high vacuum (UHV) range. The outgassing rate describes the amount of gases that are released from various materials under negative pressure. Standard plastics release such gases at high vacuum - PEEK, on the other hand, has an extraordinarily low outgassing rate, which greatly benefits UHV applications.
PEEK even meets the strict requirements of the aerospace industry in terms of outgassing rate. Other areas of application in the UHV sector include semiconductor technology and the energy sector.
Conclusion
PEEK has been used for some time as a guarantee for outstanding mechanical, thermal and chemical properties in a wide range of industries. However, the combination of this material with 3D printing opens up a wide range of additional application areas.
The high degree of design freedom, the ease of manufacturing complex components, the fast speed and all the other advantages offered by 3D printing enable more productive and efficient production of these high-quality PEEK components.
If you already have a project that benefits from the properties of 3D printing and PEEK, then we are the ideal partner for you. Simply upload your digital model here and we will get back to you as soon as possible to implement your project to your complete satisfaction.
Thank you for your attention - and see you in the next blog post!
