High Performance 3D Printing Materials: PEEK, ULTEM and Other Polymers

Source: 3dnatives.com

In recent years, high-performance materials have become a very controversial topic in the 3D printing community. In a world that is constantly changing and adapting to new technologies and materials, it was only a matter of time before high-performance thermoplastic polymers stood out among the other 3D printing materials. Polyaryletherketone (PAEK) is a family of semi-crystalline thermoplastic materials that can withstand high temperatures while maintaining exceptional strength. PAEK is primarily used in the form of polyether ether ketone (PEEK) and polyether ether ketone ketone (PEKK), both of which have high stiffness. However, a much cheaper alternative, polyetherimide (PEI), also known as ULTEM, has gained a lot of attention because it costs much less due to its lack of ketone. Find out everything you need to know about the PAEK and PEI families here.

Production and characteristics of high performance polymers

The first thing to note about high-performance polymers is that, while they share common characteristics, they are not all exactly the same. That said, in general it can be noted that high-performance thermoplastics, and the PEEK Specifically, they are as strong as steel and 80% lighter than metal, making them highly desirable in the manufacturing industry. Additionally, in addition to their exceptional mechanical and thermal strength up to 250 °C (482 °F) for continuous operation, PAEK materials are also resistant to dissolution in oils and other substances, unlike most other plastics. When exposed to fire, almost no harmful gases or fumes are released.

In fact, these materials have been around for over thirty years, mostly used for injection molding or machining. At first, Stratasys was the only company that could produce printers that could handle the high temperatures required to melt PAEK and PEI polymers. However, as the market opened up, more companies had the opportunity to experiment with these materials, resulting in their inventions becoming mass-marketed. As time goes on and the barriers to entry become lower, we see more and more companies entering the industry and starting to produce printers that can handle PAEK thermoplastics.

PEI was first developed by General Electric's plastics division in the late 1980s. In 2007, however, SABIC, a major public company in Saudi Arabia, acquired the division and thus the rights to the ULTEM brand. As this material is a lower-cost alternative to PEEK, it quickly generated a lot of financial interest. Combined with its various significant physical properties such as high heat, solvent and flame resistance, dielectric strength and thermal conductivity, it is a fantastic solution for many engineering projects. ULTEM has become the material of choice for extremely challenging engineering applications, typically in aerospace sector.

3D printing with high-performance polymers

PAEK and PEI polymers are mainly printed with FDM (fused deposition modeling) or with SLS (Selective Laser Sintering). Considering the high temperatures these polymers operate at, it is understandable that no ordinary 3D printer is capable of processing these filaments. A 3D printer for PAEK/PEI must have an extruder nozzle capable of handling temperatures of over 300°C, the melting point of these polymers. In addition, the heated bed must reach at least 150°C for the object to be detached. Finally, significant cooling mechanisms are required to ensure the correct thermal equilibrium in the closed chamber.

The post processing of high-performance materials is a necessary procedure. As with any complex FDM printed part, support is required. When dealing with PAEK and PEI, however, due to the rigidity of the final object, peeling off the support can be difficult. As a result, a variety of tools are often used to finalize the post-production of a part.

On the other hand, when it comes to SLS, the part is printed practically perfectly, without the need for extra machining. However, manufacturers must take into account the phenomenon of warping . After an object is printed and the temperature inside the chamber has dropped, the polymers tend to shrink. As a result, PAEK and PEI are widely used for printing small objects, since the larger the part, the greater the warping effect will be. Although this can be controlled to some extent by optimizing printing parameters such as speed and temperature.

The use of high-performance thermoplastics is still being refined. The manufacturing process is still being worked on and is constantly being improved. For example, as mentioned above, once an object has been printed in PAEK, further and often complex processing is still required. However, new innovations are constantly improving the process. Several companies are currently working on an FDM solution where the object support is printed in a different material so that it can be removed more easily and quickly after printing. Other companies, such as Kimya, have also started to focus on material combinations that make the best of each material possible. In this way, the final product can be made of, for example, 70% PEEK and 30% carbon fiber.

Applications

As you might imagine, a family of materials with such a large number of characteristics and qualities is used in a variety of industries. The automotive industry has quickly begun to leverage the unique capabilities of PAEK and PEI for a variety of applications. One area where PAEK and PEI have been most disruptive is in the production of rapid, low-cost tools for injection molding, thermoforming, workholding, and accessories. This allows companies to produce low- to medium-volume parts at low cost without having to invest in large-scale production. Additionally, the production of custom parts is increasingly in demand as they can be modified to meet specific requirements and can withstand complex changes to improve their structure.

As with many other 3D printing materials, the PAEK and PEI families are widely used in the medical field. PEEK is famous for its use in shielding for magnetic resonance imaging (MRI) machines. It is also considered an advanced biological material used in medical implants and in reinforcing rods and spinal fusion devices. Its ability to withstand boiling water and superheated steam makes it perfect for objects that need to be sterilized at extremely high temperatures.

High-performance thermoplastics are also widely used in the aerospace industry. Chemical resistance, high strength-to-weight ratio, and low fire, smoke, and toxicity make these polymers ideal replacements for metals, often used for aircraft parts and machine parts. Thermal and acoustic insulation, structural brackets, clamps and spacers, fasteners, connectors, and tubing are just a few examples of where the aerospace industry has begun to use PAEK and PEI, often reducing part weight by as much as 70%. Other industries that use high-performance materials include marine, nuclear, oil and gas, and many others.

Top manufacturers and price of high performance materials

Many of the large chemical companies have quickly recognized the importance of high-performance thermoplastics in the field of additive manufacturing. As a result, leading companies such as Arkema, Lehmann & Voss, and Solvay (to name a few) are among the leading producers of PAEK materials. As for PEI, however, SABIC’s ULTEM brand is the only one currently available on the market.

In terms of printers that can support PAEK and PEI, the Chinese manufacturer INTAMSYS has received a lot of attention as it offers a range of professional and desktop 3D printers. However, the Dutch Tractus3D is becoming increasingly popular, as is the German giant EOS, which has released the HTLS (High temperature laser sintering) printer capable of processing these materials.

That said, as you might expect, these high-performance polymers aren't cheap. PEEK, UTLEM, and PEKK are some of the most expensive 3D printing materials available on the market. Although the ULTEM is a slightly cheaper alternative, a 1kg spool of filament starts at over $200 and often costs much more depending on the brand and properties of the material. PEEK, on ​​the other hand, often costs over $300 and up to over $700 for 1kg of material, while PEKK costs on average between $400 and $500 for the same amount.

Not only that, but if you are interested in filament, you should also keep in mind that not just any printer can print it. You need to invest in a printer designed for high-performance polymers, as mentioned above. These printers are understandably more expensive than a standard FDM model. In fact, some start at over $5,000, but they are generally much more expensive. However, over the years we have seen that as the market grows, so do the choices available to consumers. Perhaps in the near future we will see both printer and material prices drop as high-performance polymer applications become more widespread. additive manufacturing.