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Characterisation of 3D printed sand moulds using micro-focus X-ray computed tomography

Tharmalingam Sivarupan (Mechanics, Surfaces and Materials Processing, Laboratoire MSMP-EA7350, Arts et Métiers ParisTech – Centre d’Aix-en-Provence, France)
Mohamed El Mansori (Mechanics, Surfaces and Materials Processing, Laboratoire MSMP-EA7350, Arts et Métiers ParisTech – Centre d’Aix-en-Provence, France)
Keith Daly (Faculty of Engineering and the Environment, University of Southampton, Southampton, UK)
Mark Noel Mavrogordato (Faculty of Engineering and the Environment, University of Southampton, Southampton, UK)
Fabrice Pierron (Faculty of Engineering and the Environment, University of Southampton, Southampton, UK)

Rapid Prototyping Journal

ISSN: 1355-2546

Article publication date: 26 October 2018

Issue publication date: 25 February 2019

312

Abstract

Purpose

Micro-focus X-ray computed tomography (CT) can be used to quantitatively evaluate the packing density, pore connectivity and provide the basis for specimen derived simulations of gas permeability of sand mould. This non-destructive experiment or following simulations can be done on any section of any size sand mould just before casting to validate the required properties. This paper aims to describe the challenges of this method and use it to simulate the gas permeability of 3D printed sand moulds for a range of controlling parameters. The permeability simulations are compared against experimental results using traditional measurement techniques. It suggests that a minimum volume of only 700 × 700 × 700 µm3 is required to obtain, a reliable and most representative than the value obtained by the traditional measurement technique, the simulated permeability of a specimen.

Design/methodology/approach

X-ray tomography images were used to reconstruct 3D models to simulate them for gas permeability of the 3D printed sand mould specimens, and the results were compared with the experimental result of the same.

Findings

The influence of printing parameters, especially the re-coater speed, on the pore connectivity of the 3D printed sand mould and related permeability has been identified. Characterisation of these sand moulds using X-ray CT and its suitability, compared to the traditional means, are also studied. While density and 3PB strength are a measure of the quality of the moulds, the pore connectivity from the tomographic images precisely relates to the permeability. The main conclusions of the present study are provided below. A minimum required sample size of 700 × 700 × 700 µm3 is required to provide representative permeability results. This was obtained from sand specimens with an average sand grain size of 140 µm, using the tomographic volume images to define a 3D mesh to run permeability calculations. Z-direction permeability is always lower than that in the X-/Y-directions due to the lower values of X-(120/140 µm) and Y-(101.6 µm) resolutions of the furan droplets. The anisotropic permeability of the 3D printed sand mould is mainly due to, the only adjustable, X-directional resolution of the furan droplets; the Y-directional resolution is a fixed distance, 102.6 µm, between the printhead nozzles and the Z-directional one is usually, 280 µm, twice the size of an average sand grain.A non-destructive and most representative permeability value can be obtained, using the computer simulation, on the reconstructed 3D X-ray tomography images obtained on a specific location of a 3D printed sand mould. This saves time and effort on printing a separate specimen for the traditional test which may not be the most representative to the printed mould.

Originality/value

The experimental result is compared with the computer simulated results.

Keywords

Acknowledgements

The financial support provided by the rapid casting platform, at the MSMP laboratory, of the Low-Cast project is greatly acknowledged. Authors acknowledge the assistance provided by the μ-VIS CT Imaging Centre for the X-ray tomography and the IRIDIS High-Performance Computing Facilities of The University of Southampton, UK. The authors thank Prof Carlos H Caceres, The University of Queensland, for valuable feedback on the final draft. Tharmalingam Sivarupan’s current affiliation is School of Mechanical and Mining Engineering, The University of Queensland, Queensland, Australia.

Citation

Sivarupan, T., El Mansori, M., Daly, K., Mavrogordato, M.N. and Pierron, F. (2019), "Characterisation of 3D printed sand moulds using micro-focus X-ray computed tomography", Rapid Prototyping Journal, Vol. 25 No. 2, pp. 404-416. https://doi.org/10.1108/RPJ-04-2018-0091

Publisher

:

Emerald Publishing Limited

Copyright © 2018, Emerald Publishing Limited

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