Poly‐Ether‐Ether‐Ketone Melt Behavior in Fused Deposit Modeling Printing Moves

ABSTRACT Polyetheretherketone (PEEK) offers superior mechanical and thermal properties for use in non‐assembly mechanisms manufactured by fused deposition modeling (FDM). However, the required precise control of the shear and cooling behavior during printing is still not sufficiently explored, which is limiting tolerance, accuracy, and functionality. This work investigates the shear viscosity and transient heat transfer of PEEK melt in FDM using rheological measurements, polarized light microscopy (PLM), differential scanning calorimetry (DSC), and a one‐dimensional numerical simulation including power‐law viscosity and heat conduction. Experiments show a thin solidified layer (~47–54 μm) at the print bed interface that solidifies rapidly without significant shear, leading to higher effective shear rates in the remaining melt and thus a larger orientation gradient across the strand height. PLM investigations indicate increasing birefringence at shear rates up to ~350 s −1 , consistent with growing molecular orientation, though contributions from crystalline morphology cannot be fully excluded. Surface instabilities follow at critical shear rates of approximately 750–810 s −1 . The simulation results align with the obtained solidified layer thickness and the shear profiles obtained by the experiments. A corrected shear rate equation is proposed to correct the effect of the unsheared, solidified layer. The findings presented in this work enhance the understanding of melt kinematics in FDM‐PEEK printing and provide a basis for informed parameter selection in the fabrication of non‐assembly mechanisms, contributing to improved tolerance control and reduced risk of surface defects.