How to ensure dimensional accuracy of FDM 3D printed PEEK parts?Agnieszka
While FDM 3D printing, complications may occur when processing large-size elements, such as the two-piece 40 cm model shown in the photo above, which, in addition to restrictive dimensional parameters, required the clearance along the entire element to be maintained while maintaining high strength parameters.
Dimensional accuracy depends not only on the technology in which we produce a given 3D print but also on materials out of which we build our element. Polymer’s technical parameters define the mechanical features of the given printout. We can’t forget about the importance of additional parameters, such as printer calibration, the type of used filament, and finally, the ambient temperature conditions.
Regarding heat and chemical resistance, the PEEK (Polyether Ether Ketone) polymer, as one of the high-strength engineering materials used for additive printing in FDM technology, meets the highest technological standards.
In addition to very high dimensional resistance, PEEK is characterized by excellent thermal and chemical resistance, high mechanical strength, stiffness and hardness, and low flammability, accompanied by a low level of smoke emission during the material combustion. Thanks to such a compilation of mechanical properties, PEEK is increasingly used as a substitute for materials such as steel or aluminium, devoid of undesirable properties. Eliminated disadvantages include the formation of corrosion centers or the inability to release ions. Undoubtedly, its lightness and impulse strength testify to its quality. PEEK is at the top of the pyramid in the category of high-performance polymers.
Overall, technology (material shrinkage or the possibility of a minimum printhead feeding) and the material properties themselves influence the model’s actual dimensional representation. It is crucial because the dimensional accuracy requirements in specialist industries such as the automotive, military, or aviation go hand in hand with the use and development of innovative plastics. In the case of PEEK, for instance, abrasion resistance, accompanied by a low friction ratio, is a key factor in extreme operating conditions.
The use of this high-performance polymer with undoubted advantages, as an alternative to the metals, requires 3D printers that meet the stringent specifications of industrial prints, guaranteeing the final strength of the printed parts. Since models can experience significant temperature fluctuations during the forming process, it is essential to control printer functions such as adjusting optimal nozzle temperature and regulating a heated chamber, and a heated bed ensuring the heat treatment. These 3D printing machine properties affect the dimensional accuracy, namely allowing the production of different degrees of crystallinity and mechanical properties (among others modulus of elasticity, tensile strength) for various elements made of PEEK polymer, taking into account different areas of the same model.
The dimensional tolerances in 3D printing are relatively more significant compared to cutting or injection molding processes. Although the semi-crystalline structure of PEEK has many advantages, it must not be forgotten that this material’s crystallization process must be controlled in additive manufacturing. To efficiently print from PEEK, you will need a 3D printer (VSHAPER 270 PRO, VSHAPER 500 PRO) with an extruder that can reach 400 °C, a heated chamber up to 70-100 °C, and a build platform that can heat up to 100 °C.
A comprehensive delineation of the discussed topic also requires mentioning the support structures themselves, as poorly prepared support structures affect the dimensional accuracy and are essential for the precise preservation of the model geometry. FS11 is a material soluble in an alkaline solution that can be used in PEEK prints. It is an alternative to mechanically removed supports, especially when it is impossible to remove them safely out of the model. FS11 material is distinguished by good adhesion to model materials – which helps to prevent delamination of the base material and surface distortions.
3D printing aims to print to the highest standard in one automated production stage. First, setting the printout on the working platform, then verifying the generated supports, finally selecting the optimal fillings (optimization of technological parameters guaranteed by the SOFTSHAPER software with a wide range of filling structures). The 3D printing technology, thanks to the use of innovative polymer materials, makes the purchase of parts, which production with other methods is inaccessible or unprofitable, fast and easy. Even when rapid production is needed technology meets dimensional and durability requirements.