Characterisation of powder-filled defects in additive manufactured surfaces using X-ray CT

Research output: Chapter in Book/Report/Conference proceedingConference contribution

Abstract

Assessing functional performance is the most important stage of any component verification. Mechanical properties can be evaluated by means of destructive testing which can be both expensive and lengthy in addition to loss of the original component under test. It is therefore advantageous where possible to utilise non-destructive techniques that can achieve the same or similar outcomes through collection of three-dimensional data that can then be used in simulation to determine functionality. Such non-destructive methods with 3D location ability are essentially density- and porosity-based testing methods. Additive manufacturing allows the creation of complex geometrical features that are often defined based on function.
Optimisation of AM component geometry based on functionality allows for the specification of components that have features that cannot be mapped efficiently to current GPS standards ISO 14638. In addition, the integrity of complex optimised AM structures that may lie on a critical stress or heat path must be assessed and any elements of unfused powder for example, must be detected. This seeks to investigate the ability of X-ray computer tomography to detect and characterised small scale empty and powder filled defects which may occur in AM manufactured parts. To achieve this, aim a Ti6AL4V artefact built using an Arcam Q10 electron beam-melting machine (EBM). Defects of between 50 and 1400 microns in diameter were machined into the surface of the artefact using a precision CNC machine equipped with micro-drills. Once this was achieved, the defects were characterised using focus variation microscope. Virgin Ti6AL4V powder was added to fill 50% of the defects and then the artefact was measured using a Nikon XTH225 industrial CT. This was used to analyse the relative size and volume of the defects and assess the capability of the inspection process to both assess the size of pores and to detect the powder-filled defects. To reduce the number of process variables, all the measurement process parameters, such as filament current, acceleration voltage and X-ray filtering material and thickness, were kept constant between the scans with hollow and powder filled defects. The acquired data processing, surface determination process and defect analysis was carried out using VgStudio Max (Volume Graphics, Germany). The focus of the study is on providing best practice regarding the selection of inspection parameters and identifying the capability of the process to detect unfused powder.
LanguageEnglish
Title of host publication8th Conference on Industrial Computed Tomography
Number of pages8
Publication statusPublished - 1 Feb 2018
Event8th Conference on Industrial Computed Tomography - University of Applied Science Upper Austria, Wels, Austria
Duration: 6 Feb 20189 Feb 2018
Conference number: 8
https://www.diondo.com/index.php/de/computertomografie/neuigkeiten/198-conference-industrial-computed-tomography-2018 (Link to Conference Details )

Publication series

NameOpen Access Database of Nondestructive Testing
ISSN (Electronic)1435-4934

Conference

Conference8th Conference on Industrial Computed Tomography
Abbreviated titleICT 2018
CountryAustria
CityWels
Period6/02/189/02/18
Internet address

Fingerprint

Powders
X rays
Defects
3D printers
Inspection
Electron beam melting
Testing
Density (specific gravity)
Tomography
Global positioning system
Microscopes
Porosity
Specifications
Mechanical properties
Geometry
Electric potential

Cite this

Tawfik, A., Bills, P., Blunt, L., & Racasan, R. (2018). Characterisation of powder-filled defects in additive manufactured surfaces using X-ray CT. In 8th Conference on Industrial Computed Tomography (Open Access Database of Nondestructive Testing).
Tawfik, Ahmed ; Bills, Paul ; Blunt, Liam ; Racasan, Radu. / Characterisation of powder-filled defects in additive manufactured surfaces using X-ray CT. 8th Conference on Industrial Computed Tomography. 2018. (Open Access Database of Nondestructive Testing).
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Tawfik, A, Bills, P, Blunt, L & Racasan, R 2018, Characterisation of powder-filled defects in additive manufactured surfaces using X-ray CT. in 8th Conference on Industrial Computed Tomography. Open Access Database of Nondestructive Testing, 8th Conference on Industrial Computed Tomography, Wels, Austria, 6/02/18.

Characterisation of powder-filled defects in additive manufactured surfaces using X-ray CT. / Tawfik, Ahmed; Bills, Paul; Blunt, Liam; Racasan, Radu.

8th Conference on Industrial Computed Tomography. 2018. (Open Access Database of Nondestructive Testing).

Research output: Chapter in Book/Report/Conference proceedingConference contribution

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N2 - Assessing functional performance is the most important stage of any component verification. Mechanical properties can be evaluated by means of destructive testing which can be both expensive and lengthy in addition to loss of the original component under test. It is therefore advantageous where possible to utilise non-destructive techniques that can achieve the same or similar outcomes through collection of three-dimensional data that can then be used in simulation to determine functionality. Such non-destructive methods with 3D location ability are essentially density- and porosity-based testing methods. Additive manufacturing allows the creation of complex geometrical features that are often defined based on function.Optimisation of AM component geometry based on functionality allows for the specification of components that have features that cannot be mapped efficiently to current GPS standards ISO 14638. In addition, the integrity of complex optimised AM structures that may lie on a critical stress or heat path must be assessed and any elements of unfused powder for example, must be detected. This seeks to investigate the ability of X-ray computer tomography to detect and characterised small scale empty and powder filled defects which may occur in AM manufactured parts. To achieve this, aim a Ti6AL4V artefact built using an Arcam Q10 electron beam-melting machine (EBM). Defects of between 50 and 1400 microns in diameter were machined into the surface of the artefact using a precision CNC machine equipped with micro-drills. Once this was achieved, the defects were characterised using focus variation microscope. Virgin Ti6AL4V powder was added to fill 50% of the defects and then the artefact was measured using a Nikon XTH225 industrial CT. This was used to analyse the relative size and volume of the defects and assess the capability of the inspection process to both assess the size of pores and to detect the powder-filled defects. To reduce the number of process variables, all the measurement process parameters, such as filament current, acceleration voltage and X-ray filtering material and thickness, were kept constant between the scans with hollow and powder filled defects. The acquired data processing, surface determination process and defect analysis was carried out using VgStudio Max (Volume Graphics, Germany). The focus of the study is on providing best practice regarding the selection of inspection parameters and identifying the capability of the process to detect unfused powder.

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M3 - Conference contribution

T3 - Open Access Database of Nondestructive Testing

BT - 8th Conference on Industrial Computed Tomography

ER -

Tawfik A, Bills P, Blunt L, Racasan R. Characterisation of powder-filled defects in additive manufactured surfaces using X-ray CT. In 8th Conference on Industrial Computed Tomography. 2018. (Open Access Database of Nondestructive Testing).