The PEEK 3D Printing Guide

PEEK (polyetheretherketone) is a colorless, organic, thermoplastic polymer that is difficult to process in 3D printing. For years, 3D printer manufacturers have used PEEK as a flagship product in their marketing campaigns. However, the actual printing results often fall far short of expectations.

PEEK offers a unique combination of high mechanical strength, chemical resistance, and temperature resistance up to over 250°C. Furthermore, it is biocompatible and inherently flame-retardant, making it an ideal metal substitute.

Pure PEEK can only be 3D printed using the extrusion process with filament (FFF/FDM) or granules (FGF). It is unsuitable for powder printing (e.g., SLS) because the laser cannot couple into the material. For SLS machines, there are heavily modified materials that bear the name PEEK, but their heat resistance, for example, is not at all comparable to that of the material it is named after.

Modern printing processes achieve over 95% of the strength of injection-molded parts, especially with optimized layer adhesion. The Z-axis usually remains the weak point, but this can be improved through targeted process management (build chamber temperature).

Due to its high shrinkage rate during cooling, PEEK requires considerable expertise in print preparation (scaling factors). With optimized processes, tolerances in the range of +/- 0.1 mm are achievable.

The high processing temperatures make shaping very difficult and therefore expensive. The raw material must first be processed into granules and then, in a second step, into filament (plastic wire). Thus, costs increase with each processing step. Furthermore, the low global production compared to other plastics makes the price highly dependent on demand.

The same basic requirements apply as for other plastics in 3D printing with FDM (FFF, with filament) or FGF (with granules). The layer structure necessitates the support of undercuts and steep overhangs. These can be reduced through clever design (e.g., overhangs up to a 45° slope).

The processing takes place on specially designed machines. High temperatures at the extruder, print bed, and print chamber, as well as tailored software, must be perfectly coordinated. To date, there are no turnkey solutions in this segment.

You need a printer with a high-temperature extruder (up to 500°C), a heated print bed (ideally 200°C), and, most importantly, an actively heated build chamber (at least 90-120°C). Without this constant heat, warping and poor layer adhesion will occur.

Crystallinity determines the mechanical properties; excessively rapid cooling leads to amorphous (translucent-brown) PEEK, which is weaker. A controlled thermal process ensures the typical beige, semi-crystalline structure with maximum stability.

PEEK is the only thermoplastic that remains dimensionally stable even at temperatures up to 250 °C. Furthermore, it has high wear resistance, making it a good alternative to metallic materials, especially for wear parts.

Pure PEEK is an excellent electrical insulator. However, there are special compounds with carbon fibers or graphite that have been modified for ESD protection or electrical conductivity. Glass fiber reinforced PEEK is also an excellent electrical insulator and thus an easier-to-process alternative to pure PEEK.

The main disadvantage of PEEK is the complexity and high cost of its production, as well as its lack of thermoformability.

PEEK as a raw material (pellets) costs between €50 and €120/kg. As a filament (plastic wire), the price is around €500/kg. These prices always depend on the manufacturer and the specific material formulation.

Printed PEEK can be milled, drilled, or turned exceptionally well, similar to hard metals or very hard plastics. It is significantly more dimensionally stable during machining than, for example, PA6 or POM.

Chemical smoothing processes are currently not feasible on an industrial scale for PEEK due to its extreme resistance. Surface improvements are usually achieved mechanically through grinding, blasting, or polishing.

PEEK can be bonded without problems, both with and without fiber content. A two-component mixture is used for this purpose, which cures within 24 hours.

Due to its properties, PEEK is the king of plastics and correspondingly expensive. If its applications don't technically preclude other plastics, PEEK is not competitive. In applications that precisely define its load-bearing limits...

Yes, PEEK has an extremely low outgassing rate and is therefore ideally suited for applications in aerospace engineering or semiconductor manufacturing. This also applies to additively manufactured PEEK components.