Steady melting in material extrusion additive manufacturing
ISSN: 1355-2546
Article publication date: 12 December 2023
Issue publication date: 2 January 2024
Abstract
Purpose
A main cause of defects within material extrusion (MatEx) additive manufacturing is the nonisothermal condition in the hot end, which causes inconsistent extrusion and polymer welding. This paper aims to validate a custom hot end design intended to heat the thermoplastic to form a melt prior to the nozzle and to reduce variability in melt temperature. A full 3D temperature verification methodology for hot ends is also presented.
Design/methodology/approach
Infrared (IR) thermography of steady-state extrusion for varying volumetric flow rates, hot end temperature setpoints and nozzle orifice diameters provides data for model validation. A finite-element model is used to predict the temperature of the extrudate. Model tuning demonstrates the effects of different model assumptions on the simulated melt temperature.
Findings
The experimental results show that the measured temperature and variance are functions of volumetric flow rate, temperature setpoint and the nozzle orifice diameter. Convection to the surrounding air is a primary heat transfer mechanism. The custom hot end brings the melt to its setpoint temperature prior to entering the nozzle.
Originality/value
This work provides a full set of steady-state IR thermography data for various parameter settings. It also provides insight into the performance of a custom hot end designed to improve the robustness of melting in MatEx. Finally, it proposes a strategy for modeling such systems that incorporates the metal components and the air around the system.
Keywords
Acknowledgements
Portions of this work is supported by the National Science Foundation (NSF) under GOALI Grant No. #1914651 and NIST Science and Technical Research and Services. Any opinions, findings, and conclusions or recommendations expressed in this material are those of the author(s) and do not necessarily reflect the views of the NSF or NIST. The authors also acknowledge Stratasys, Ltd. as the University of Massachusetts (UMass) Lowell team’s GOALI partner, and especially Tim Diekmann for his ongoing interest and support.
Since submission of this article, the following author has updated their affiliation: Austin R. Colon is at the Materials Science and Engineering Division, National Institute of Standards and Technology, Gaithersburg, Maryland, USA.
Citation
Colon, A.R., Kazmer, D.O., Peterson, A.M. and Seppala, J.E. (2024), "Steady melting in material extrusion additive manufacturing", Rapid Prototyping Journal, Vol. 30 No. 1, pp. 85-94. https://doi.org/10.1108/RPJ-06-2023-0185
Publisher
:Emerald Publishing Limited
Copyright © 2023, Jonathan E. Seppala.