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Geometric characterization of orthogonally printed layers in material extrusion additive manufacturing: numerical modeling and experiments

Authors:
Sina Jafarzadeh at Technical University of Denmark
Sina Jafarzadeh
Raphaël Comminal at Flow Science Inc.
Raphaël Comminal
  • Flow Science Inc.
Marcin P. Serdeczny
Marcin P. Serdeczny
Marcin P. Serdeczny
  • This person is not on ResearchGate, or hasn't claimed this research yet.
Mohamad Bayat at Technical University of Denmark
Mohamad Bayat
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Abstract and Figures

This study shows how a computational fluid dynamics (CFD) model can be used as a complementary approach to investigate the influence of processing parameters on the morphology of printed strands, in material extrusion additive manufacturing (AM). Experimental investigations were also realized to validate the numerical model. Both experiments and numerical simulations were employed to quantify the deformation of a molten polymeric strand extruded on top of an uneven substrate constituted of previously printed parallel strands. This configuration occurs when a structure is printed with a rectilinear infill pattern and alternate raster angles from layer to layer. The deformation of the molten strand is mainly influenced by the gap distance between the strands of the previous layer and the speed ratio of the nozzle displacement to the extrusion volumetric flux. Numerical simulations are able to capture variations in the strand’s shape, under different printing conditions. Finally, the numerical model also provides an estimate of the interlayer contact area, which was not possible to measure in experiments, but constitutes a critical parameter for the mechanical properties of 3D-printed parts.
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Vol.:(0123456789)
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Progress in Additive Manufacturing (2023) 8:1619–1630
https://doi.org/10.1007/s40964-023-00426-7
FULL RESEARCH ARTICLE
Geometric characterization oforthogonally printed layers
inmaterial extrusion additive manufacturing: numerical modeling
andexperiments
SinaJafarzadeh1 · RaphaëlComminal2,3· MarcinP.Serdeczny2,3· MohamadBayat2· ChristianR.H.Bahl1·
JonSpangenberg2
Received: 4 October 2022 / Accepted: 19 February 2023 / Published online: 9 March 2023
© The Author(s), under exclusive licence to Springer Nature Switzerland AG 2023
Abstract
This study shows how a computational fluid dynamics (CFD) model can be used as a complementary approach to investigate
the influence of processing parameters on the morphology of printed strands, in material extrusion additive manufacturing
(AM). Experimental investigations were also realized to validate the numerical model. Both experiments and numerical
simulations were employed to quantify the deformation of a molten polymeric strand extruded on top of an uneven substrate
constituted of previously printed parallel strands. This configuration occurs when a structure is printed with a rectilinear infill
pattern and alternate raster angles from layer to layer. The deformation of the molten strand is mainly influenced by the gap
distance between the strands of the previous layer and the speed ratio of the nozzle displacement to the extrusion volumetric
flux. Numerical simulations are able to capture variations in the strand’s shape, under different printing conditions. Finally,
the numerical model also provides an estimate of the interlayer contact area, which was not possible to measure in experi-
ments, but constitutes a critical parameter for the mechanical properties of 3D-printed parts.
Keywords Material extrusion additive manufacturing· Fused deposition modeling· Computational fluid dynamics
modeling· Experimental validation· Strand’s morphology· Interlayer contact area
1 Introduction
Material extrusion additive manufacturing (AM) is used for
rapid prototyping, but also to produce functional parts. A
wide variety of materials can be 3D printed, which is an
alternative reference to AM, including (but not limited to)
plastics [1, 2], hydrogels [3–5], ceramic pastes [6], metals
[7], and concrete [8, 9] as well as multi-material 3D print-
ing [10, 11,18]. Different extrusion technologies exist for
the different types of materials and their typical ranges of
print volumes.
For thermoplastics, the main technology is fused filament
fabrication (FFF) also known as fused deposition modeling
(FDM) or material extrusion additive manufacturing (MEX),
where a filament is pushed through and melted inside a liq-
uefier mounted on the printhead. The soften thermoplastic
is then extruded from the hot-end nozzle and deposited layer
by layer. Thermoplastics cool down rapidly after extrusion
to below glass temperature. The printhead toolpath is gen-
erated from the CAD geometry of the part and the chosen
infill parameters. The typical FFF workflow is illustrated
in Fig.1. The resolution of the print depends on the layer
height and the nozzle diameter. However, several other
parameters influence the quality of the prints, including the
extrusion temperature, the substrate temperature, the 3D
printing speed, the extrusion speed, and the infill pattern
of the layers.
Some of the challenges in FFF—and extrusion AM in
general—include improving the geometrical conformity
(dimensional tolerance and surface quality) and mechanical
* Sina Jafarzadeh
sinja@dtu.dk
1 Department ofEnergy Conversion andStorage,
Technical University ofDenmark, Anker Engelunds Vej,
2800Kgs.Lyngby, Denmark
2 Department ofMechanical Engineering, Technical University
ofDenmark, Produktionstorvet, 2800Kgs.Lyngby, Denmark
3 Flow Science, Inc, 683 Harkle Road, SantaFe, NM87505,
USA
Content courtesy of Springer Nature, terms of use apply. Rights reserved.
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