Numerical modeling of the polymer flow through the hot-end in filament-based material extrusion additive manufacturing

Serdeczny, Marcin P.; Comminal, Raphaël; Mollah, Md. Tusher; Pedersen, David Bue; Spangenberg, Jon

doi:10.1016/j.addma.2020.101454

Cited by 53 publications

(69 citation statements)

References 32 publications

(60 reference statements)

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“…The extrusion pressure range obtained in this study is comparable to that obtained using mathematical formulation discussed by Phan et al [32]. The pressure at inlet varies from 5 to 120 bar depending on the material and V e [33]. This corresponds to an inlet thrust force and torque rating consistent with most stepper motors used in extruders of FFF printers.…”

Section: Effect Of Melt Viscosity On Pressuresupporting

confidence: 83%

Implementation of viscosity and density models for improved numerical analysis of melt flow dynamics in the nozzle during extrusion-based additive manufacturing

et al. 2021

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Fused Filament Fabrication (FFF) is an Additive Manufacturing (AM) process that builds up a part via layer by layer deposition of polymeric material. The purpose of this study is to implement viscosity and density models for improving the assessment of melt flow behavior inside the nozzle during deposition. Numerical simulations are carried out for different combinations of important process parameters like extrusion velocity Ve, extrusion temperature Te, and filament material (Acrylonitrile Butadiene Styrene (ABS) and Polylactic Acid (PLA)). Cross-Williams–Landel–Ferry (Cross-WLF) viscosity and Pressure–Volume–Temperature (PVT) density models are incorporated to get realistic results. Distribution of printing parameters like pressure, temperature, velocity and viscosity inside the nozzle are observed at steady state and their relationship with the print quality is discussed. Effect of the PVT model on polymer deposition is illustrated by comparing it with deposition considering a constant density. Velocity profiles are obtained for the different cases considered and locations where the flow is fully developed, along the axial distance of the nozzle, are determined and termed as stable zones. A direct correlation between the position of the developed melt flow profile and printing quality is established and the best combination of printing parameters is proposed for ABS and PLA. Extended stable zones are obtained for the polymer melt in the nozzle at Ve = 60 mm/s, Te = 220 °C for ABS and Ve = 30 mm/s and Te = 195 °C for PLA and hence, these can be considered as the optimum values of the printing parameters.

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Section: Effect Of Melt Viscosity On Pressuresupporting

confidence: 83%

Implementation of viscosity and density models for improved numerical analysis of melt flow dynamics in the nozzle during extrusion-based additive manufacturing

et al. 2021

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“…In general, for polymer melts involved in extrusion processes the Reynolds number can be considered small, 30 hence the flow is laminar and the effects of both the inertial and gravity forces can be neglected. Besides that, the assumption shall be made that the material has an isotropic and incompressible behavior, which corresponds closely with the behavior of most metals and polymers.…”

Section: Hypothesis and Governing Equationsmentioning

confidence: 99%

Simulation of the viscoplastic extrusion process using the radial point interpolation meshless method

Costa

Belinha

Jorge

et al. 2021

Proceedings of the Institution of Mechanical Engineers, Part L:

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Additive manufacturing is an emergent technology, which witnessed a large growth demanded by the consumer market. Despite this growth, the technology needs scientific regulation and guidelines to be reliable and consistent to the point that is feasible to be used as a source of manufactured end-products. One of the processes that has seen the most significant development is the fused deposition modeling, more commonly known as 3D printing. The motivation to better understand this process makes the study of extrusion of materials important. In this work, the radial point interpolation method, a meshless method, is applied to the study of extrusion of viscoplastic materials, using the formulation originally intended for the finite element method, the flow formulation. This formulation is based on the reasoning that solid materials under those conditions behave like non-Newtonian fluids. The time stepped analysis follows the Lagrangian approach taking advantage of the easy remeshing inherent to meshless methods. To validate the newly developed numerical tool, tests are conducted with numerical examples obtained from the literature for the extrusion of aluminum, which is a more common problem. Thus, after the performed validation, the algorithm can easily be adapted to simulate the extrusion of polymers in fused deposition modeling processes.

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“…The simulations were run until a steady state was reached, or for 60 s, when the flow was inherently unsteady. A more in-depth discussion about the implementation of the numerical model can be found in [27]. Right: close-up on the contraction section.…”

Section: Implementation Detailsmentioning

confidence: 99%

“…It was hypothesized that the maximum feeding rate is limited by the heat transfer and the ability to melt the filament completely before it reaches the nozzle contraction. A more detailed explanation of the extrusion instability was given in a follow-up work [27] presenting numerical simulations of the flow inside the print head. The feeding force instability was hypothesized to be due to a fluctuation of the melt zone position inside the flow channel.…”

Section: Introductionmentioning

confidence: 99%

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Influence of Fibers on the Flow Through the Hot-End in Material Extrusion Additive Manufacturing

Serdeczny

Comminal

Pedersen

et al. 2020

Industrializing Additive Manufacturing

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Advancements in material extrusion additive manufacturing are driven by the need of fast production of high-quality parts. A key innovation was the introduction of short fibers into the built filament, which substantially improve the strength of manufactured components. However, the presence of fibers also affects the viscosity and thermal conductivity of the filament, which are important parameters for the extrusion flow and thus the maximum printing speed. In this paper, we numerically study the effect of fibers on the polymer flow and pressure drop inside the nozzle, which determines the maximum extrusion rate. The thermoplastic polymer flow is simulated with a non-isothermal computational fluid dynamics model and the inclusion of fibers is treated with a continuum approach. The simulations are performed for ABS polymer with short carbon fibers, however, other thermoplastic systems with short fibers (e.g. glass, wood, or nylon) can be integrated into the model. The model provides a virtual window into the process and illustrates that while fibers increase the viscosity of the filament and the pressure drop, they also improve the thermal conductivity and lead to faster melting of the polymer, which has an opposite effect on the pressure drop. Finally, the model quantifies the relationship between the fiber volume fraction and the maximum extrusion rate.

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Numerical modeling of the polymer flow through the hot-end in filament-based material extrusion additive manufacturing

Cited by 53 publications

References 32 publications

Implementation of viscosity and density models for improved numerical analysis of melt flow dynamics in the nozzle during extrusion-based additive manufacturing

Implementation of viscosity and density models for improved numerical analysis of melt flow dynamics in the nozzle during extrusion-based additive manufacturing

Simulation of the viscoplastic extrusion process using the radial point interpolation meshless method

Influence of Fibers on the Flow Through the Hot-End in Material Extrusion Additive Manufacturing

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