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Proceedings Paper

Assessing the use of an infrared spectrum hyperpixel array imager to measure temperature during additive and subtractive manufacturing
Author(s): Eric Whitenton; Jarred Heigel; Brandon Lane; Shawn Moylan
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Paper Abstract

Accurate non-contact temperature measurement is important to optimize manufacturing processes. This applies to both additive (3D printing) and subtractive (material removal by machining) manufacturing. Performing accurate single wavelength thermography suffers numerous challenges. A potential alternative is hyperpixel array hyperspectral imaging. Focusing on metals, this paper discusses issues involved such as unknown or changing emissivity, inaccurate greybody assumptions, motion blur, and size of source effects. The algorithm which converts measured thermal spectra to emissivity and temperature uses a customized multistep non-linear equation solver to determine the best-fit emission curve. Emissivity dependence on wavelength may be assumed uniform or have a relationship typical for metals. The custom software displays residuals for intensity, temperature, and emissivity to gauge the correctness of the greybody assumption. Initial results are shown from a laser powder-bed fusion additive process, as well as a machining process.

In addition, the effects of motion blur are analyzed, which occurs in both additive and subtractive manufacturing processes. In a laser powder-bed fusion additive process, the scanning laser causes the melt pool to move rapidly, causing a motion blur-like effect. In machining, measuring temperature of the rapidly moving chip is a desirable goal to develop and validate simulations of the cutting process. A moving slit target is imaged to characterize how the measured temperature values are affected by motion of a measured target.

Paper Details

Date Published: 11 May 2016
PDF: 13 pages
Proc. SPIE 9861, Thermosense: Thermal Infrared Applications XXXVIII, 986106 (11 May 2016); doi: 10.1117/12.2222575
Show Author Affiliations
Eric Whitenton, National Institute of Standards and Technology (United States)
Jarred Heigel, National Institute of Standards and Technology (United States)
Brandon Lane, National Institute of Standards and Technology (United States)
Shawn Moylan, National Institute of Standards and Technology (United States)

Published in SPIE Proceedings Vol. 9861:
Thermosense: Thermal Infrared Applications XXXVIII
Joseph N. Zalameda; Paolo Bison, Editor(s)

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