Coaxial color channel focus evaluation to estimate standoff height in directed energy deposition additive manufacturing

Callan Herberger; Lauren Heinrich; Erik LaNeave; Brian Post; Kenton B. Fillingim; Eric MacDonald; Thomas Feldhausen; James Haley

doi:10.1007/s40964-024-00572-6

Coaxial color channel focus evaluation to estimate standoff height in directed energy deposition additive manufacturing

Callan Herberger, Lauren Heinrich, Erik LaNeave, Brian Post, Kenton B. Fillingim, Eric MacDonald, Thomas Feldhausen, James Haley

Research output: Contribution to journal › Article › peer-review

1 Scopus citations

Abstract

Directed energy deposition (DED) is an additive manufacturing process that is being rapidly adopted by industry and is well suited for the fabrication of complex components in a variety of metal alloys. In laser cladding systems such as DED, powder is blown in a stream to a metal substrate coincident with a laser necessary to deposit molten metal with 3D spatial control. The focus of both the laser and the powder stream are crucial, and best deposition occurs at a predetermined standoff height between the build surface and the print head. Generally, no monitoring of this distance is implemented in commercial DED systems. Due to potential over or under building, the standoff height often changes over time but tends to self-correct. However, inexpensive and minimally intrusive methods to identify optimal standoff are required to provide real-time control to maintain the optimal distance. The present work explores the quantification of the focus of the three-color channels of a coaxial camera to determine the standoff height. An experiment was performed in which a 254 mm wall is built and the standoff height, initially 5.0 mm below the optimal position, was then intentionally increased every 25.4 mm of wall length by an amount of 1.0 mm to a final position 7.0 mm above optimal. Computer vision is demonstrated to monitor the amount of focus in each color band and estimate standoff distance. A response can be calculated in under 40 ms using simple hardware and can work in most laser-based DED systems.

Original language	English
Pages (from-to)	2199-2211
Number of pages	13
Journal	Progress in Additive Manufacturing
Volume	9
Issue number	6
DOIs	https://doi.org/10.1007/s40964-024-00572-6
State	Published - Dec 2024

Funding

This manuscript has been authored by UT-Battelle, LLC under Contract No. DE-AC05-00OR22725 with the U.S. Department of Energy and University of Texas-El Paso under Contract No. FA8650-20-2-5700 with Air Force Research Laboratory. This effort was performed through the National Center for Defense Manufacturing and Machining under the America Makes Program entitled \u201CHybrid Manufacturing for Rapid Tooling and Repair\u201D. The United States Government retains and the publisher, by accepting the article for publication, acknowledges that the United States Government retains a non-exclusive, paid-up, irrevocable, world-wide license to publish or reproduce the published form of this manuscript, or allow others to do so, for United States Government purposes. The Department of Energy will provide public access to these results of federally sponsored research in accordance with the DOE Public Access Plan (http://energy.gov/downloads/doe-public-access-plan). The authors would like to highlight the support from the Murchison Chair at the University of Texas at El Paso. The views and conclusions contained in this document are those of the authors and should not be interpreted as necessarily representing the official policies or endorsements, either expressed or implied, of the Air Force Research Laboratory or the U.S. Government. This manuscript has been authored by UT-Battelle, LLC under Contract No. DE-AC05-00OR22725 with the U.S. Department of Energy and University of Texas-El Paso under Contract No. FA8650-20-2-5700 with Air Force Research Laboratory. This effort was performed through the National Center for Defense Manufacturing and Machining under the America Makes Program entitled \u201CHybrid Manufacturing for Rapid Tooling and Repair\u201D. The United States Government retains and the publisher, by accepting the article for publication, acknowledges that the United States Government retains a non-exclusive, paid-up, irrevocable, world-wide license to publish or reproduce the published form of this manuscript, or allow others to do so, for United States Government purposes. The Department of Energy will provide public access to these results of federally sponsored research in accordance with the DOE Public Access Plan ( http://energy.gov/downloads/doe-public-access-plan ). The authors would like to highlight the support from the Murchison Chair at the University of Texas at El Paso.

Funders	Funder number
Air Force Research Laboratory
United States Government
University of Texas at El Paso
DOE Public Access Plan
National Center for Defense Manufacturing and Machining
U.S. Department of Energy and University of Texas-El Paso	FA8650-20-2-5700

Keywords

Computer vision
Focus quantification
Hybrid directed energy deposition
Standoff height

UN SDGs

This output contributes to the following UN Sustainable Development Goals (SDGs)

Access to Document

10.1007/s40964-024-00572-6

Cite this

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title = "Coaxial color channel focus evaluation to estimate standoff height in directed energy deposition additive manufacturing",

abstract = "Directed energy deposition (DED) is an additive manufacturing process that is being rapidly adopted by industry and is well suited for the fabrication of complex components in a variety of metal alloys. In laser cladding systems such as DED, powder is blown in a stream to a metal substrate coincident with a laser necessary to deposit molten metal with 3D spatial control. The focus of both the laser and the powder stream are crucial, and best deposition occurs at a predetermined standoff height between the build surface and the print head. Generally, no monitoring of this distance is implemented in commercial DED systems. Due to potential over or under building, the standoff height often changes over time but tends to self-correct. However, inexpensive and minimally intrusive methods to identify optimal standoff are required to provide real-time control to maintain the optimal distance. The present work explores the quantification of the focus of the three-color channels of a coaxial camera to determine the standoff height. An experiment was performed in which a 254 mm wall is built and the standoff height, initially 5.0 mm below the optimal position, was then intentionally increased every 25.4 mm of wall length by an amount of 1.0 mm to a final position 7.0 mm above optimal. Computer vision is demonstrated to monitor the amount of focus in each color band and estimate standoff distance. A response can be calculated in under 40 ms using simple hardware and can work in most laser-based DED systems.",

keywords = "Computer vision, Focus quantification, Hybrid directed energy deposition, Standoff height",

author = "Callan Herberger and Lauren Heinrich and Erik LaNeave and Brian Post and Fillingim, {Kenton B.} and Eric MacDonald and Thomas Feldhausen and James Haley",

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AU - MacDonald, Eric

AU - Feldhausen, Thomas

AU - Haley, James

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