Numerical Simulation and Experimental Study Regarding the Cross-Sectional Morphology of PEEK Monofilament Deposition During FDM-Based 3D Printing.

Polyether-ether-ketone (PEEK) is widely used in the field of biomedical engineering because of its excellent mechanical properties, chemical stability, and biocompatibility. Fused deposition modeling (FDM), which is a typical 3D printing process, can achieve low-cost and high-efficiency printing of complex PEEK structures. However, poor monofilament deposition quality leads to rough surfaces on macroscopic printed parts, low dimensional accuracy, and weak interlayer bonding, which are urgent problems to be solved. In this study, considering the shear thinning characteristic of PEEK, a numerical model for monofilament deposition was constructed by using the finite volume method. This model revealed the influences of process parameters on the monofilament cross-sectional profiles and achieved predictions of monofilament cross-sectional profiles during FDM-based 3D printing of PEEK. The average relative error of the monofilament cross-sectional area predictions was 7.68%. The average relative error of the monofilament cross-sectional aspect ratio predictions was 12.06%. It was also found that there are three typical deposited monofilament cross-sectional profile shapes, i.e., a capsule shape, a bread shape, and a circular shape. These three shapes occurred because of the combined effect of the layer thickness and the extrusion width during the extrusion and deposition of PEEK. These revealed monofilament cross-sectional profiles provide the basis for accurate nozzle motion trajectory planning, and they lay a foundation for surface roughness predictions and dimensional accuracy control during the FDM-based 3D printing of PEEK.