PEEK 3D Printing
PEEK (Polyether ether ketone) is an exceptionally durable plastic that’s used throughout a variety of industries. It can be machined as well as injection molded. And while it is capable of being 3D printed, it is surprisingly difficult to find 3D printers capable of working with PEEK. In this article, we’ll talk about what PEEK is, where it’s used, and the few solutions available for 3D printing PEEK.
What is PEEK?
PEEK is a rigid opaque industrial thermoplastic that is part of the PAEK (Polyaryletherketone) family. It is known for its strength and stability. PEEK has a semi-crystalline bond structure when it solidifies which gives it high durability, resistance to most chemicals, and resistance to moisture absorption. As such, PEEK is capable of handling corrosive fluids, gases, water, steam, and more that are found in high stress environments. Additionally, the crystalline structure gives PEEK high resistance to wear and fatigue.
Although PEEK has a strong chemical resistance and is insoluble in many common solvents, once PEEK reaches temperatures above 392°F, it may have trouble resisting interactions with elements such as Fluorine, Chlorine/Bromide, concentrated Sulphur, Nitric acids, and more. PEEK also has low resistance to UV light, but coatings are available in post-processing to help with this.
Because of these characteristics, PEEK performs well in many applications. The main industries that utilize it are aerospace, automotive, electrical, oil, medical, and culinary.
Aerospace & Automotive
PEEK’s insulating properties, light weight, and resistance to such a broad temperature range make it excellent to use as parts for planes and cars. Since these means of transport are exposed to varying temperatures and weather environments, PEEK offers a durable alternative to heavy steel and aluminum parts.
Electrical & Oil
Its insulative properties, flame retardancy, and resistance to corrosion make PEEK ideal for use in the electrical and oil industries. PEEK components can make working conditions safer in these industries by preventing fires and leaks.
Medical & Culinary
Along with being resistant to most chemicals, PEEK is also biocompatible and easy to sterilize. For this reason, PEEK has been used for implants and bone reconstruction. These implants are superior to metal or other plastics because PEEK becomes translucent when exposed to X-Ray, MRI, or CT radiation. This allows medical technicians and doctors to better examine the area being scanned without the implant obstructing their view. In addition to this, PEEK is inert and FDA approved, making its use in culinary preparation very practical.
3D Printing with PEEK
Filament Extrusion 3D Printing
Extrusion 3D printing involves a heated print head extruding plastic filament onto a build platform, working layer by layer to construct the part. Extrusion 3D printers typically produce parts from thermoplastics such as ABS or PLA. Some industrial 3D printers also offer more durable materials like polycarbonate or ULTEM.
3D printed PEEK, on the other hand, is surprisingly difficult to come by. Stratasys, the largest manufacturer of extrusion 3D printers, offers PEKK rather than PEEK for its machines. And while there are a number of 3D printers from other companies capable of printing PEEK, they would be difficult for most companies to justify purchasing due to either a small build chamber, limited material selection, or extremely high cost.
Stratasys 3D Printers
Stratasys printers are perhaps the best suited printers for PEEK on the market. Stratasys’s patented closed and heated build chamber, trademarked as FDM (Fused Deposition Modeling), ensures that the extruded material is kept hot in the space between the print head and the build tray. This is exceptionally important for PEEK since this material must be processed at such a high temperature. If the build chamber is exposed or unheated, the crystalline structure of PEEK will not form correctly and may weaken the part.
But, unfortunately, Stratasys does not offer PEEK filament for their machines. Instead, they offer a material called Antero 800NA, which is a PEKK-based material. While PEKK (Polyetherketoneketone) and PEEK come from the same PAEK family of plastics, they are not the same. The primary difference between the two is that PEEK is able to withstand temperatures almost 100°F higher than PEKK.
Other Extrusion Printers
Any extrusion 3D printer that is not by Stratasys is typically referred to as FFF (Fused Filament Fabrication), which is similar to FDM but has a crucial component missing. FFF lacks the patented closed and heated build chamber. This can make a huge difference with PEEK because the material will start to cool in the short distance between the print head and build tray and the crystalline bond may be distorted, resulting in curling or warping.
Since the Stratasys patent specifies that the motors and other such components be outside the build chamber, some companies have worked around the patent by placing motion control systems inside the build chamber of their 3D printers. While this seems like a good loophole, placing these elements inside the build chamber can cause problems, such as overheating and high costs due to the need for high heat-resistant components.
The Apium P220 is an FFF 3D printer that supports a variety of materials, including PEEK. However, this machine has faltered in some tests where it has resulted in warped edges on parts printed in PEEK. Also, this printer has a maximum build volume of only 8.6” x 6.8” x 6.3”, which is half the build box size of a smaller Stratasys Fortus FDM printer. An Apium P220 can cost an average of $50,000-$100,000, which is 30-50% of the cost of a Fortus.
Tractus 3D T650P
The Tractus 3D T650P is a lightweight 3D printer capable of printing a number of materials, but is specifically designed for PEEK. It does have a closed build chamber and a heated build tray. But with a maximum temperature of 350°F the build chamber can’t get hot enough to ensure consistent high quality prints with PEEK. Its build volume is 6.7” x 6.7” x 11.2” which is relatively small. The reality is that this printer is on the lower end of industrial 3D printers and is only a slight step up from a consumer printer. This machine costs an average of $10,000 and up.
If you’re searching for a more compact, less expensive way to print PEEK, you may be wondering about desktop 3D printers. Unfortunately, the average desktop 3D printer cannot handle the temperatures needed to properly print a part with PEEK. While some may have print head nozzles that reach the required temperatures, prolonged use can be damaging to the machine and result in faulty parts and a lot of repairs on the machine.
Selective Laser Sintering
The process of laser sintering involves a bed of material in powder form that is melted with a fine laser that traces the shape of a cross-sectional layer of your design. Once a layer is completed, a new layer of powder is deposited for the laser to melt. When the part is completed, the excess powder is removed and the part goes through post-processing.
EOS is the leading SLS equipment manufacturer, and the the only company to offer sintering for PEEK. Below are two main EOS laser sintering printers in more detail.
EOS P 800
The EOS P 800 is a laser sintering printer that specializes in PEEK. Specifically, EOS uses a material called PEEK HP3 in all of this machine’s print jobs. While the build volume is very large (27.6″ x 15.0″ x 22.4″) and its quality is superb, this printer costs upwards of $250,000. As such, this method of producing PEEK is a huge investment. Even 3D printing service bureaus would find it difficult to justify.
EOS P 810
Similar to the P 800, the EOS P 810 is also a laser sintering 3D printer. However, this printer specializes in HT-23, a carbon fiber reinforced PEKK material made only for this printer. To create this machine, EOS partnered with Boeing to design a laser sintering printer that would cater to the aerospace industry. The P 810 can create parts that match the specifications needed for airplanes and more, with one of the main goals being to reduce weight in the parts. This printer operates two 70-watt lasers and has a build volume of 27.6” x 15” x 15” This newer technology is expected to start at the same base price as the EOS P 800.
Do You Really Need to 3D Print?
Due to the extremely limited availability of 3D printed PEEK, you may have to resort to traditional manufacturing technologies to get your parts made. If you absolutely must have PEEK, but can’t justify buying your own printer, you can always look into having your parts machined or injection molded.
While it’s a little more complicated than other materials, PEEK can be machined. This may be a suitable replacement for 3D printing PEEK parts for low-volume applications. Whether you’re prototyping or field testing, machining is an ideal solution when you only need a small number of parts. Additionally, machined parts tend to be stronger than 3D printed parts, which is probably important for applications requiring a material as strong as PEEK. For a more thorough comparison of 3D printing and CNC milling and the costs associated with each, click here.
If you need more than a few parts, you may be better off with injection molding. Even with the cost of cutting your tooling, injection molding is usually more economical when making more than a couple dozen parts. And, like machining, molding will almost always produce stronger parts than 3D printing. For comparison and cost breakdown of 3D printing vs injection molding, click here.
Do You Really Need PEEK?
As always, it is important to consider your part’s intended use. If your part must work in fluctuating temperatures and under a lot of stress, PEEK’s abilities may outweigh its costs. On the other hand, if your part will not be used in such demanding stress conditions or will be exposed to extreme heat, perhaps it may benefit you to consider ULTEM or PPSF for the most cost effective solution that will still provide the quality of part you require.
A type of PEI (Polyetherimide), ULTEM is a thermoplastic that can compete with PEEK in high temperatures. While its tensile and flexural strengths and moduli are 30-40% lower than those of PEEK, its HDT is only 1°F different. Additionally, its glass transition temperature is much higher than PEEK, allowing for this material to be used in hotter environments. Furthermore, ULTEM is UV resistant where PEEK is not, making it ideal for outdoor use.
While lower in strength compared to PEEK and ULTEM, this material is still more durable than most other FDM plastics. Additionally, it has a HDT and glass transition temperature much higher than either PEEK or ULTEM. It is also self-extinguishing, making it ideal for any high-heat application.
|Tensile Strength||14,210 psi||9,950 psi||8,000 psi|
|Tensile Modulus||580,150 psi||329,000 psi||300,000 psi|
|Flexural Strength||23,930 psi||16,200 psi||15,900 psi|
|Flexural Modulus||551,143 psi||331,000 psi||320,000 psi|
3D Printing at 3 Space
Here at 3 Space, we offer both ULTEM and PPSF for your printing needs. If you’re unsure whether PEEK or one of these materials will better suit your part’s requirements, our technicians will gladly assess your part’s design and intended use to assist you in making the best decision for your part.