AccScience Publishing / ESAM / Volume 2 / Issue 4 / DOI: 10.36922/ESAM026360019
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ORIGINAL RESEARCH ARTICLE

Vision-derived stability indicators from melt pool and wire dynamics in laser hot-wire directed energy deposition

Mario Rodriguez-Parra1,2* ,  Miguel Hoffmann2 ,  Mithulan Paramanathan2 ,  Thomas Feldhausen1,2 ,  Eric MacDonald2,3
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1 Aerospace and Mechanical Engineering, The University of Texas at El Paso, El Paso, Texas , United States of America
2 Manufacturing Science Division, Oak Ridge National Laboratory, Tennessee , United States of America
3 Industrial and Systems Engineering, University of Florida, Gainesville, Florida , United States of America
ESAM 2026, 2(4), 026360019 https://doi.org/10.36922/ESAM026360019
Received: 1 September 2026 | Revised: 2 October 2026 | Accepted: 15 October 2026 | Published online: 2 November 2026
© 2026 by the Author(s). This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution 4.0 International License ( https://creativecommons.org/licenses/by/4.0/ )
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Abstract

Laser hot-wire directed energy deposition (LHW-DED) improves process performance by enhancing wire preheating. Reliable in situ assessment of process stability remains challenging because the melt-pool behavior and wire transfer are commonly evaluated separately. This study develops vision-derived stability indicators by jointly characterizing melt-pool geometry and wire dynamics during the deposition of stainless steel 316LSi under varying laser power and hot-wire power. Optical videos were analyzed using multi-Otsu segmentation for melt-pool area extraction and the Segment Anything Model 2 for temporal wire segmentation. Melt-pool area was used to characterize the energy input, while frame-to-frame Intersection over Union (IoU), IoU volatility, and angle variability were evaluated as indicators of wire stability. Low energy conditions produced smaller melt pools and greater wire flutter, whereas sufficient energy inputs produced larger melt pools and more consistent wire behavior. Parameter-level correlations showed that melt-pool area for single beads was related to penetration depth and total cross-sectional area measured by optical microscopy. Melt-pool area was also associated with wire stability during the single-bead laser-power sweep. These results establish melt-pool geometry and wire dynamics as complementary indicators of LHW-DED stability and support future process qualification and in situ feedback control.

Graphical abstract
Keywords
Laser hot-wire directed energy deposition
Computer vision
Additive manufacturing
In situ monitoring
Funding
This material is based on research sponsored by Air Force Research Laboratory under Agreement Number FA8650-20-2-5700. The U.S. Government is authorized to reproduce and distribute reprints for Governmental purposes notwithstanding any copyright notation thereon. This research was supported in part by an appointment to the Oak Ridge National Laboratory GRO Program, sponsored by the U.S. Department of Energy and administered by the Oak Ridge Institute for Science and Education. This work was supported by the US Department of Energy, Office of Energy Efficiency and Renewable Energy, Advanced Materials and Manufacturing Technologies Office under contract number DE-AC05-00OR22725.
Conflict of interest
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.
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