Thermal near infrared monitoring system for electron beam melting with emissivity tracking

Boone, Nicholas Andrew; Zhu, Chengxi; Todd, Iain; Willmott, Jon R.

doi:10.1016/j.addma.2018.06.004

Cited by 39 publications

(44 citation statements)

References 8 publications

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“…Non-contact monitoring methods, such as infra-red (IR) thermography, provide the most straightforward opportunity to achieve this. The area of in-situ monitoring in LBPF has seen a great deal of attention recently and there are now examples in the literature of taking part-scale thermal measurements of the process using IR thermography [19,20,21]. However these frequently lack calibration and do not report absolute temperature.…”

Section: Introductionmentioning

confidence: 99%

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In situ thermography for laser powder bed fusion: Effects of layer temperature on porosity, microstructure and mechanical properties

Williams

Piglione

Rønneberg

et al. 2019

Additive Manufacturing

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In laser powder bed fusion (LPBF) the surface layer temperature is continually changing throughout the build process. Variations in part geometry, scanned cross-section and number of parts all inuence the thermal eld within a build. Process parameters do not take these variations into account and this can result in increased porosity and dierences in local microstructure and mechanical properties, undermining condence in the structural integrity of a part. In this paper a wide-eld in-situ infra-red imaging system is developed and calibrated to enable measurement of both solid and powder surface temperatures across the full powder bed. The inuence of inter-layer cooling time is investigated using a build scenario with cylindrical components of diering heights. In-situ surface temperature data are acquired throughout the build process and are compared to results from porosity, microstructure and mechanical property investigations. Changes in surface temperature of up to 200°C are attributed to variation in inter-layer cooling time and this is found to correlate with density and grain structure changes in the part. This work shows that these changes are signicant and must be accounted for to improve the consistency and structural integrity of LPBF components.

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Section: Introductionmentioning

confidence: 99%

“…They are primarily used for process control, using arbitrary intensity values measured via IR as a control variable. Boone et al [20] were able to achieve calibrated temperature measurements in Electron Beam Melting (EBM), although information on the uncertainty is limited.…”

Section: Introductionmentioning

confidence: 99%

In situ thermography for laser powder bed fusion: Effects of layer temperature on porosity, microstructure and mechanical properties

Williams

Piglione

Rønneberg

et al. 2019

Additive Manufacturing

View full text Add to dashboard Cite

show abstract

“…Infrared (IR) spectroscopy and imaging are growing in demand due to the increasing number of applications in this spectral region, including optical tomography, 1 process monitoring, 2 food and agriculture quality control, 3 and night vision devices, 4 as well as LIDAR and remote sensing. 5,6 Commercial IR imaging detectors rely on the absorption of incident photons in narrow bandgap semiconductor materials and the release of electrons that are electrically detected.…”

Section: Introductionmentioning

confidence: 99%

Infrared upconversion imaging in nonlinear metasurfaces

Camacho‐Morales

Rocco

et al. 2021

Adv. Photon.

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Infrared imaging is a crucial technique in a multitude of applications, including night vision, autonomous vehicle navigation, optical tomography, and food quality control. Conventional infrared imaging technologies, however, require the use of materials such as narrow bandgap semiconductors, which are sensitive to thermal noise and often require cryogenic cooling. We demonstrate a compact all-optical alternative to perform infrared imaging in a metasurface composed of GaAs semiconductor nanoantennas, using a nonlinear wave-mixing process. We experimentally show the upconversion of short-wave infrared wavelengths via the coherent parametric process of sum-frequency generation. In this process, an infrared image of a target is mixed inside the metasurface with a strong pump beam, translating the image from the infrared to the visible in a nanoscale ultrathin imaging device. Our results open up new opportunities for the development of compact infrared imaging devices with applications in infrared vision and life sciences.

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“…[7] Metallization of the view port is usually counteracted by a sacrificial spooling Kapton film. [5][6][7] Drawbacks of this approach are the high amount of data to be processed [8] and the susceptibility to errors, for example, due to inaccurate temperature calibration or failing of the Kapton film. [7] To overcome these limitations regarding monitoring of an entire build process, a second type of IR imaging is applied.…”

Section: Introductionmentioning

confidence: 99%

In Operando Monitoring by Analysis of Backscattered Electrons during Electron Beam Melting

2019

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Additive manufacturing by electron beam melting (EBM) is a complex process, which still lacks reliable tools for process monitoring. Demanding processing conditions such as high temperature, high vacuum, and X‐ray radiation impede the continuous operation of standard process monitoring devices such as light‐optical camera systems. To overcome this deficit, the detection of backscattered electrons (BSEs) is a highly promising approach. A detection system for BSEs is used for recording the in operando signal during melting inside an EBM system. The acquired data are postprocessed by mapping the data points to spatial coordinates. A comparison between the obtained intensity map and the as‐built surface shows a remarkable correlation, which might be suitable for process monitoring and quality control purposes.

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Thermal near infrared monitoring system for electron beam melting with emissivity tracking

Cited by 39 publications

References 8 publications

In situ thermography for laser powder bed fusion: Effects of layer temperature on porosity, microstructure and mechanical properties

In situ thermography for laser powder bed fusion: Effects of layer temperature on porosity, microstructure and mechanical properties

Infrared upconversion imaging in nonlinear metasurfaces

In Operando Monitoring by Analysis of Backscattered Electrons during Electron Beam Melting

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