Spatter transport by inert gas flow in selective laser melting : a simulation study

Spattering is an unavoidable phenomenon during Selective Laser Melting (SLM). The distinctively large and dark solidified molten particles have always been observed on the powder bed, leading to the potential deterioration of the final printed parts. In commercial SLM machines, inert gas flow is pum...

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Main Authors: Ahmad Bin Anwar, Ibrahim, Imran Halimi, Pham, Quang-Cuong
Other Authors: School of Mechanical and Aerospace Engineering
Format: Article
Language:English
Published: 2020
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Online Access:https://hdl.handle.net/10356/141001
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Institution: Nanyang Technological University
Language: English
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spelling sg-ntu-dr.10356-1410012023-03-04T17:22:24Z Spatter transport by inert gas flow in selective laser melting : a simulation study Ahmad Bin Anwar Ibrahim, Imran Halimi Pham, Quang-Cuong School of Mechanical and Aerospace Engineering Singapore Centre for 3D Printing Engineering::Mechanical engineering Additive Manufacturing Selective Laser Melting Spattering is an unavoidable phenomenon during Selective Laser Melting (SLM). The distinctively large and dark solidified molten particles have always been observed on the powder bed, leading to the potential deterioration of the final printed parts. In commercial SLM machines, inert gas flow is pumped into the chamber over the powder bed to remove spatter and other unwanted by-products such as metal vapour and plasma plumes. However, traces of spatter still remain on the powder bed and the regions close to the chamber outlet. In this work, the trajectories of spatter particles were tracked using the Discrete Phase Model (DPM). The continuous fluid domain was solved using three-dimensional Computational Fluid Dynamics (CFD) simulations. The entrainment effects on the hot ejections as well as the recoil pressure driven ejections were considered. In other words, it was assumed that the latter were also entrained by the metal vapour and laser plume. The final distribution characteristics downstream of the cross-flow (-x direction) were validated by an earlier experimental study. The results show that a gradually decreasing trend in terms of the spatter size and mass distributions were obtained from the simulations which showed good agreement with the earlier experiments. It was also shown that the trajectories of the spatter particles were governed mainly by their initial momentum when the inert gas flow velocity was increased. While complete removal of the spatter particles from the powder bed was not achieved, the presence of the inert gas flow aided in the transport of a majority of the particles further downstream giving a more even mass distribution. Also, in spite of not accounting for the complete multi-physics of the SLM process and the associated recoil pressure driven ejections, the proposed spatter transport simulations can be applied in future gas cross-flow optimisation designs for the effective removal of spatter over the powder bed in commercial SLM machines. Accepted version 2020-06-03T06:30:32Z 2020-06-03T06:30:32Z 2019 Journal Article Ahmad Bin Anwar, Ibrahim, I. H., & Pham, Q.-C. (2019). Spatter transport by inert gas flow in selective laser melting : a simulation study. Powder Technology, 352, 103-116. doi:10.1016/j.powtec.2019.04.044 0032-5910 https://hdl.handle.net/10356/141001 10.1016/j.powtec.2019.04.044 2-s2.0-85064931375 352 103 116 en Powder Technology © 2019 Elsevier B.V. All rights reserved. This paper was published in Powder Technology and is made available with permission of Elsevier B.V. application/pdf
institution Nanyang Technological University
building NTU Library
continent Asia
country Singapore
Singapore
content_provider NTU Library
collection DR-NTU
language English
topic Engineering::Mechanical engineering
Additive Manufacturing
Selective Laser Melting
spellingShingle Engineering::Mechanical engineering
Additive Manufacturing
Selective Laser Melting
Ahmad Bin Anwar
Ibrahim, Imran Halimi
Pham, Quang-Cuong
Spatter transport by inert gas flow in selective laser melting : a simulation study
description Spattering is an unavoidable phenomenon during Selective Laser Melting (SLM). The distinctively large and dark solidified molten particles have always been observed on the powder bed, leading to the potential deterioration of the final printed parts. In commercial SLM machines, inert gas flow is pumped into the chamber over the powder bed to remove spatter and other unwanted by-products such as metal vapour and plasma plumes. However, traces of spatter still remain on the powder bed and the regions close to the chamber outlet. In this work, the trajectories of spatter particles were tracked using the Discrete Phase Model (DPM). The continuous fluid domain was solved using three-dimensional Computational Fluid Dynamics (CFD) simulations. The entrainment effects on the hot ejections as well as the recoil pressure driven ejections were considered. In other words, it was assumed that the latter were also entrained by the metal vapour and laser plume. The final distribution characteristics downstream of the cross-flow (-x direction) were validated by an earlier experimental study. The results show that a gradually decreasing trend in terms of the spatter size and mass distributions were obtained from the simulations which showed good agreement with the earlier experiments. It was also shown that the trajectories of the spatter particles were governed mainly by their initial momentum when the inert gas flow velocity was increased. While complete removal of the spatter particles from the powder bed was not achieved, the presence of the inert gas flow aided in the transport of a majority of the particles further downstream giving a more even mass distribution. Also, in spite of not accounting for the complete multi-physics of the SLM process and the associated recoil pressure driven ejections, the proposed spatter transport simulations can be applied in future gas cross-flow optimisation designs for the effective removal of spatter over the powder bed in commercial SLM machines.
author2 School of Mechanical and Aerospace Engineering
author_facet School of Mechanical and Aerospace Engineering
Ahmad Bin Anwar
Ibrahim, Imran Halimi
Pham, Quang-Cuong
format Article
author Ahmad Bin Anwar
Ibrahim, Imran Halimi
Pham, Quang-Cuong
author_sort Ahmad Bin Anwar
title Spatter transport by inert gas flow in selective laser melting : a simulation study
title_short Spatter transport by inert gas flow in selective laser melting : a simulation study
title_full Spatter transport by inert gas flow in selective laser melting : a simulation study
title_fullStr Spatter transport by inert gas flow in selective laser melting : a simulation study
title_full_unstemmed Spatter transport by inert gas flow in selective laser melting : a simulation study
title_sort spatter transport by inert gas flow in selective laser melting : a simulation study
publishDate 2020
url https://hdl.handle.net/10356/141001
_version_ 1759858084182753280