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

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

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.

3D sand mould, Alloys, Casting, Computer simulation, Gas permeability, X-ray tomography
1355-2546
404-416
Sivarupan, Tharmalingam
50cdeb08-688c-4837-908d-350165d54d68
El Mansori, Mohamed
e280f7e4-34b4-4907-a407-a094673d4c8a
Daly, Keith
86eba68d-74e8-4db8-aaea-141705d079f6
Mavrogordato, Mark Noel
f3e0879b-118a-463a-a130-1c890e9ab547
Pierron, Fabrice
a1fb4a70-6f34-4625-bc23-fcb6996b79b4
Sivarupan, Tharmalingam
50cdeb08-688c-4837-908d-350165d54d68
El Mansori, Mohamed
e280f7e4-34b4-4907-a407-a094673d4c8a
Daly, Keith
86eba68d-74e8-4db8-aaea-141705d079f6
Mavrogordato, Mark Noel
f3e0879b-118a-463a-a130-1c890e9ab547
Pierron, Fabrice
a1fb4a70-6f34-4625-bc23-fcb6996b79b4

Sivarupan, Tharmalingam, El Mansori, Mohamed, Daly, Keith, Mavrogordato, Mark Noel and Pierron, Fabrice (2019) Characterisation of 3D printed sand moulds using micro-focus X-ray computed tomography. Rapid Prototyping Journal, 25 (2), 404-416. (doi:10.1108/RPJ-04-2018-0091).

Record type: Article

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.

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More information

Accepted/In Press date: 10 July 2018
e-pub ahead of print date: 26 October 2018
Published date: 2019
Keywords: 3D sand mould, Alloys, Casting, Computer simulation, Gas permeability, X-ray tomography

Identifiers

Local EPrints ID: 427737
URI: http://eprints.soton.ac.uk/id/eprint/427737
ISSN: 1355-2546
PURE UUID: 6a51a039-930c-4dba-9ce6-64a866c98bd7
ORCID for Fabrice Pierron: ORCID iD orcid.org/0000-0003-2813-4994

Catalogue record

Date deposited: 25 Jan 2019 17:30
Last modified: 26 Nov 2021 02:55

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Contributors

Author: Tharmalingam Sivarupan
Author: Mohamed El Mansori
Author: Keith Daly
Author: Fabrice Pierron ORCID iD

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