Views: 0 Author: Site Editor Publish Time: 2025-12-31 Origin: Site
Polyetheretherketone (PEEK) is a semi-crystalline aromatic thermoplastic specialty engineering plastic. Since its introduction in the late 1960s, it has occupied an important position in the field of new materials due to its outstanding comprehensive performance. The melting point of PEEK is 343℃, its glass transition temperature is 143℃, the continuous service temperature can reach 260℃, and the short-term temperature resistance can be as high as 300℃. Its density is only 1.3g/cm³, yet it possesses mechanical strength comparable to that of metals - tensile strength exceeds 100MPa, and flexural strength can reach 165MPa.
High-temperature resistance
high strength and rigidity
excellent chemical stability (showing outstanding resistance to most chemicals and solvents)
biocompatibility (meeting medical implant standards), Flame retardancy (UL94 V-0 grade)
wear resistance and cut resistance .
These characteristics have enabled it to be widely applied in high-demand fields such as aerospace, medical implants, automotive manufacturing, and electronic and electrical engineering.
Fused Deposition Modeling (FDM) is the most commonly used 3D printing technology for thermoplastic materials in additive manufacturing. A typical FDM printer mainly consists of a heat sink, a throat tube, a heating block and a nozzle. The print head uses friction as the driving force to push the unmelted material at the rear forward, thereby forcing the melted material at the front end out of the nozzle. As the inner diameter of the throat is larger than that of the filament, if the throat does not dissipate heat in time during the printing process, the melted material at the front end will not only be squeezed out from the nozzle but also form a backflow in the gap between the throat and the filament, increasing the friction between the filament and the throat. In severe cases, the material may overflow from the rear end of the throat, resulting in a "plug" phenomenon. [citation:1][citation:2]
The high melting point characteristic of PEEK material poses extremely strict requirements for 3D printing equipment:
High-temperature Nozzle System : The nozzle temperature must be stably maintained between 400 and 450℃. It is necessary to be equipped with high-temperature resistant heating blocks, thermocouples and nozzles (hardened steel, ruby or ceramic nozzles are recommended).
High-temperature heating bed : One of the biggest challenges in printing PEEK is to prevent warping. The temperature of the heating bed needs to reach 120-150℃ to reduce the temperature difference between the printed part and the build plate and lower internal stress.
Closed constant temperature chamber : Absolutely necessary. PEEK is extremely sensitive to temperature fluctuations. Cold air can cause poor interlayer bonding, cracking and severe warping. The chamber temperature needs to be controlled between 60 and 300 degrees Celsius to ensure temperature uniformity.
High-precision temperature control system : It is necessary to be equipped with a PID closed-loop control system to keep the melt viscosity fluctuation within 3%, ensuring uniform "welding" between layers and no visible holes to the naked eye.
3.1 Core Process Parameter Settings
Nozzle Temperature : The melting point of PEEK material is 343℃, but during actual printing, the nozzle temperature needs to be set between 360 and 440℃. Too low a temperature will prevent the material from melting fully, affecting its fluidity. If the temperature is too high, it may cause the material to melt excessively, resulting in problems such as dripping and carbonization. It is recommended to set the nozzle temperature at 420℃ (with an error of ±2℃). [citation:6][citation:9]
Hot bed temperature : It is generally recommended to set it between 120 and 180℃. A higher temperature of the hot bed can effectively prevent the bottom of the printed part from warping and ensure the adhesion of the first layer. For large or complex models, the temperature of the hot bed can be appropriately increased to around 180℃. [citation:9]
Chamber temperature : It needs to be controlled between 90 and 160℃, and in some high-end equipment, it can even exceed 200℃. An appropriate chamber temperature helps maintain the crystalline state of the material and improve the mechanical properties of the printed parts. [citation:9]
Printing speed : It is generally recommended to be between 20 and 100mm/s. It is recommended to set the base speed at around 20mm/s to ensure the flatness and firmness of the base. Other layers can be set at around 30-60mm/s according to the complexity of the model. [citation:9]
Layer thickness parameter : Set between 0.1 and 0.3mm. A smaller layer height (0.1-0.15mm) is suitable for medical devices or precision parts. For models with low precision requirements, a layer thickness of 0.2 to 0.3mm can be adopted to enhance efficiency. [citation:9]
3.2 Sensitivity Analysis of Process Parameters
Through orthogonal experiments and range analysis, the order of the influence degree of each process parameter on the performance of PEEK printed parts is: printing path > pass spacing > insulation chamber temperature > layer thickness . Among them, the contribution rate of nozzle temperature to tensile strength is as high as 45.2%, which is the most crucial influencing factor. The contribution rate of layer thickness to surface roughness is 38.7%, playing a significant role in controlling surface quality. [citation:6]
The optimal combination of process parameters is as follows: nozzle temperature 420℃, scanning speed 20mm/s, platform temperature 140℃, and layer thickness 0.2mm. Under this parameter, the tensile strength of PEEK specimens can reach 86.28MPa, approaching the strength of injection-molded PEEK parts. The elastic modulus is 2.14GPa, the elongation at break is 11.36%, and the surface roughness is 12.17μm. [citation:6]
Iv. Challenges and Solutions of PEEK FDM Printing
4.1 Main Technical Challenges
High melting point and high viscosity : The melting point of PEEK is as high as 343℃, and its melt viscosity is as high as 1200Pa·s at 390℃, and still remains at 500Pa·s at 420℃. High viscosity leads to poor fluidity and is prone to clogging. [citation:1][citation:2]
Insufficient interlayer bonding force : The interlayer bonding force in the Z direction of FDM printed parts is much lower than that in the X and Y directions, which is an important factor limiting its application. Due to the rapid crystallization rate of PEEK, when the temperature of the molten PEEK is lower than the crystallization temperature, it begins to crystallize rapidly. The presence of crystals restricts the movement of molecular chains, resulting in a severe weakening of interlayer strength. [citation:3][citation:25]
Shrinkage and warping issues : PEEK is a semi-crystalline polymer. During the printing process, partial crystallization occurs. When cooled, the material significantly shrinks, which can easily lead to warping, deformation, and poor interlayer adhesion. [citation:28]
Material water absorption : PEEK material is prone to absorbing water. Wires with high water content may cause nozzle overflow and stringing during printing, resulting in poor surface quality of the model or printing failure. [citation:28]
4.2 Innovative Solutions
Fluid circulation temperature Control Print Head : By adding a fluid circulation temperature control system to the print head, the throat temperature can be reduced in a timely manner, improving the gap backflow during high-temperature printing and maintaining stable printing accuracy during long-term continuous printing. [citation:1][citation:2]
Molecular design slows down crystallization : By introducing specific copolymer groups (such as fluoroenyl rigid monomers) to modify the repeating units of PEEK, the crystallization rate is slowed down, the interlayer fusion effect is improved, and thereby the interlayer strength is enhanced. [citation:25]
Precise temperature control of the insulation chamber : When the temperature of the insulation chamber is set at 82℃, the tensile strength can reach 383.75MPa. When the temperature of the insulation chamber is 73℃, the bending strength can reach 510.13MPa. By precisely controlling the temperature of the insulation chamber, the comprehensive mechanical properties of the printed parts can be significantly improved. [citation:13]
Material Pretreatment : Before printing, dry the PEEK filament in a drying oven for 12 hours to ensure that the moisture content of the material is less than 0.02%, avoiding nozzle overflow and filament pulling during the printing process.
V. Post-processing Technology and Performance Enhancement
5.1 Annealing treatment
PEEK printed parts usually need to undergo annealing treatment to optimize their mechanical properties and dimensional stability. The annealing process steps are as follows: Prepare a dedicated oven, bake at 100℃ for 10 minutes, and then bake at 150℃ for 15 minutes after completion. After good annealing treatment, the internal stress of the material is eliminated, and the toughness and strength of the parts will also be more superior.
Annealing treatment can increase the crystallinity of PEEK printed parts from about 70% of injection-molded PEEK to close to the injection molding level, and the tensile strength can be increased to more than 100MPa (ASTM D638 standard).
5.2 Surface treatment
Due to the high-temperature characteristics and crystallization behavior of PEEK, the surface quality of the printed parts may be poor and additional surface treatment is required. Surface treatment methods, including processes such as smoothing, polishing, sandblasting, penetration or milling, can significantly improve the appearance quality and surface roughness of parts.
5.3 Vacuum venting performance
The vacuum venting performance test of FDM molded PEEK parts material shows that the mass loss rate is 0.72% and the amount of condensable volatile matter is 0.03%, meeting the vacuum venting performance requirements of space environment materials and providing a reliable guarantee for aerospace applications.
Vi. Composite Material Reinforcement Technology
6.1 Short fiber reinforced PEEK composite material
The mechanical properties of the composite material can be significantly improved by adding chopped carbon fibers (CF) or chopped glass fibers (GF) to PEEK. Among them, the maximum tensile strength of the 5wt% CF/PEEK material reaches 94MPa. The maximum flexural strength of 5wt% GF/PEEK reaches 165MPa. The introduction of fibers not only enhances the rigidity and strength of the printed parts, but also makes the crystallinity more uniform.
6.2 Continuous Fiber Reinforced PEEK composite material
Continuous fiber-reinforced PEEK composites exhibit more outstanding mechanical properties. When the temperature of the insulation chamber is 82℃, the layer thickness is 1.0mm, the printing path is 0°/0°/0°/0°, and the track spacing is 0.7mm, the tensile strength can reach 383.75MPa. When the temperature of the insulation chamber is 73℃, the layer thickness is 0.75mm, the printing path is 0°/0°/0°/0°, and the track spacing is 1.0mm, the bending strength can reach 510.13MPa.