Loose powder detection and surface characterization in selective laser sintering via optical coherence tomography

Defects produced during selective laser sintering (SLS) are difficult to non-destructively detect after build completion without the use of X-ray-based methods. Overcoming this issue by assessing integrity on a layer-by-layer basis has become an area of significant interest for users of SLS apparatu...

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Main Authors: Guan, Guangying, Hirsch, Matthias, Syam, Wahyudin P., Leach, Richard K., Huang, Zhihong, Clare, Adam T.
Format: Article
Published: Royal Society 2016
Online Access:https://eprints.nottingham.ac.uk/35287/
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author Guan, Guangying
Hirsch, Matthias
Syam, Wahyudin P.
Leach, Richard K.
Huang, Zhihong
Clare, Adam T.
author_facet Guan, Guangying
Hirsch, Matthias
Syam, Wahyudin P.
Leach, Richard K.
Huang, Zhihong
Clare, Adam T.
author_sort Guan, Guangying
building Nottingham Research Data Repository
collection Online Access
description Defects produced during selective laser sintering (SLS) are difficult to non-destructively detect after build completion without the use of X-ray-based methods. Overcoming this issue by assessing integrity on a layer-by-layer basis has become an area of significant interest for users of SLS apparatus. Optical coherence tomography (OCT) is used in this study to detect surface texture and sub-surface powder, which is un-melted/insufficiently sintered, is known to be a common cause of poor part integrity and would prevent the use of SLS where applications dictate assurance of defect-free parts. To demonstrate the capability of the instrument and associated data-processing algorithms, samples were built with graduated porosities which were embedded in fully dense regions in order to simulate defective regions. Simulated in situ measurements were then correlated with the process parameters used to generate variable density regions. Using this method, it is possible to detect loose powder and differentiate between densities of ±5% at a sub-surface depth of approximately 300 μm. In order to demonstrate the value of OCT as a surface-profiling technique, surface texture datasets are compared with focus variation microscopy. Comparable results are achieved after a spatial bandwidth- matching procedure.
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spelling nottingham-352872020-05-04T18:00:19Z https://eprints.nottingham.ac.uk/35287/ Loose powder detection and surface characterization in selective laser sintering via optical coherence tomography Guan, Guangying Hirsch, Matthias Syam, Wahyudin P. Leach, Richard K. Huang, Zhihong Clare, Adam T. Defects produced during selective laser sintering (SLS) are difficult to non-destructively detect after build completion without the use of X-ray-based methods. Overcoming this issue by assessing integrity on a layer-by-layer basis has become an area of significant interest for users of SLS apparatus. Optical coherence tomography (OCT) is used in this study to detect surface texture and sub-surface powder, which is un-melted/insufficiently sintered, is known to be a common cause of poor part integrity and would prevent the use of SLS where applications dictate assurance of defect-free parts. To demonstrate the capability of the instrument and associated data-processing algorithms, samples were built with graduated porosities which were embedded in fully dense regions in order to simulate defective regions. Simulated in situ measurements were then correlated with the process parameters used to generate variable density regions. Using this method, it is possible to detect loose powder and differentiate between densities of ±5% at a sub-surface depth of approximately 300 μm. In order to demonstrate the value of OCT as a surface-profiling technique, surface texture datasets are compared with focus variation microscopy. Comparable results are achieved after a spatial bandwidth- matching procedure. Royal Society 2016-07-20 Article PeerReviewed Guan, Guangying, Hirsch, Matthias, Syam, Wahyudin P., Leach, Richard K., Huang, Zhihong and Clare, Adam T. (2016) Loose powder detection and surface characterization in selective laser sintering via optical coherence tomography. Proceedings of the Royal Society A: Mathematical, Physical and Engineering Sciences, 472 (2191). 20160201/1-20160201/14. ISSN 1471-2946 http://dx.doi.org/10.1098/rspa.2016.0201 doi:10.1098/rspa.2016.0201 doi:10.1098/rspa.2016.0201
spellingShingle Guan, Guangying
Hirsch, Matthias
Syam, Wahyudin P.
Leach, Richard K.
Huang, Zhihong
Clare, Adam T.
Loose powder detection and surface characterization in selective laser sintering via optical coherence tomography
title Loose powder detection and surface characterization in selective laser sintering via optical coherence tomography
title_full Loose powder detection and surface characterization in selective laser sintering via optical coherence tomography
title_fullStr Loose powder detection and surface characterization in selective laser sintering via optical coherence tomography
title_full_unstemmed Loose powder detection and surface characterization in selective laser sintering via optical coherence tomography
title_short Loose powder detection and surface characterization in selective laser sintering via optical coherence tomography
title_sort loose powder detection and surface characterization in selective laser sintering via optical coherence tomography
url https://eprints.nottingham.ac.uk/35287/
https://eprints.nottingham.ac.uk/35287/
https://eprints.nottingham.ac.uk/35287/