2026 Annual International Solid Freeform Fabrication Symposium (SFF Symp 2026): Thermal Issues
Program Organizers: David Leigh, University of Texas at Austin
Wednesday 8:00 AM
August 5, 2026
Room: Zlotnick Ballroom 5
Location: AT&T Center
8:00 AM
Modular, Non-Invasive In-Situ Monitoring of Laser Powder Bed Fusion Systems: Reid Schaff1; Joshua Page1; Clark Hensley1; J Betts1; Matthew Priddy1; 1Mississippi State University
Part qualification in Laser Powder Bed Fusion (LPBF) additive manufacturing is a significant and complicated challenge, as it often requires destructive testing of high-value materials. This work presents a lightweight and non-invasive in-situ monitoring system that captures critical process data while maintaining a minimal number of sensors and a minimal amount of storge space required. As a start to this transferable open source in-situ monitoring framework, both infrared and visible-light cameras combined with thermocouples and photodiodes are integrated into an EOS M290 and recorded in a time-synchronized fashion using ROS2. OpenCV is utilized for edge detection and flagging of regions of interest within the part and helps reduce the size of each frame for efficient data handling. The proposed approach aims to identify process anomalies and provide a part-level thermal history to support user driven interpretation of part quality, without changing the LPBF system workflow.
8:20 AM
In-Situ Monitoring of the LPBF Process via MWP: Wyatt Hart1; 1W.M. Keck Center for 3d Innovatoin
Gathering thermal radiation signatures via in-situ monitoring allows a more comprehensive understanding of the complex thermal history inherent to the LPBF process — and its effect on part performance. One approach, integrated into our open-architecture LPBF system, involves multi-wavelength pyrometry (MWP). As described in our prior works, MWP permits accurate extraction of thermal signatures produced during the print process, including a measure of the emissive power of the target — solving the emissivity problem, and allowing experimentally accurate, spatially resolved temperature readings.In this work, we will discuss the steps and tests performed that contribute to that accuracy: angular dependence tests to characterize the effects of mirrors and viewports along the optical path, achromatic aberration tests to quantify the effects of measuring outside the instrument's focal length, exposure tests for fine-tuning data acquisition of features smaller than the target area, and a blackbody calibration to ensure accurate absolute thermal measurements.
8:40 AM
In-Situ Thermal Monitoring of the Laser-Powder Bed Fusion Process for Polyurethane-Modified Epoxy Thermosetting Polymer Networks: Jairam Raigar1; Rajkumar Velu1; Hadi Bakhshi2; 1Indian Institute of Technology Jammu; 2Fraunhofer Institute for Applied Polymer Research IAP
Laser-based powder bed fusion (L-PBF) of thermoplastics requires high processing temperatures (173–250 °C), which can lead to thermal aging and reduced part performance. Incorporation of thermosetting polymers offers a low-temperature alternative via in-situ crosslinking but is limited by rapid gelation and poor process control. This study experimentally investigates thermoplastic polyurethane (TPU)-modified epoxy powders for L-PBF using a selective laser polymerization (SLP) approach. TPU/epoxy blends (25/75, 50/50, 75/25 wt%) were characterized using SEM, DSC, and FTIR to assess morphology, thermal behavior, and processability. Single-layer SLP experiments combined with in-situ infrared thermography revealed improved powder flowability, melt stability, and layer uniformity with TPU addition. The 50/50 composition showed optimal performance, achieving effective melt coalescence and controlled epoxy curing at 0.304 J/mm². Results highlight the role of thermal gradients and process control in forming stable interpenetrating networks, demonstrating the potential of reactive L-PBF for advanced thermoset additive manufacturing.
9:00 AM Break
9:20 AM
Development of a Thermal Characteristics Monitoring System for the Laser-Powder Directed Energy Deposition Process: Hojin Lee1; Yoo-Ri Lee1; 1Kitech
Laser-powder Directed Energy Deposition (LP-DED) processes are widely used to develop new composite materials, repair damaged mechanical parts, and deposit dissimilar materials. The thermal characteristics of deposited parts directly affect their microstructural and mechanical properties. The purpose of this study is to develop a thermal characteristics monitoring system for the LP-DED process. An IR camera-based off-axis in-situ monitoring system was designed for the LP-DED process. Basic geometric deposition experiments, including single-line and hexahedral shapes, were performed to obtain thermal history data during the deposition process. Thermal characteristics, including maximum temperature, cooling rate, and accumulated heat, are discussed based on the thermal history data. In addition, the relationship between thermal characteristics and microstructural/mechanical properties is also discussed. From these results, the feasibility of the proposed thermal characteristics monitoring system for LP-DED is evaluated.
9:40 AM
Cooling Rate Measurement in Laser Directed Energy Deposition Using an Event-based Camera: Ainsley Soleta1; Aaron McMillen1; Samantha Webster1; 1Colorado School of Mines
Melt-pool behavior strongly influences microstructure and defect formation in laser powder-blown directed energy deposition (DED-LB). However, measuring melt-pool cooling rates in-situ remains difficult due to rapid solidification and noise while imaging. This work combines computational fluid dynamics, analytical heat transfer modeling, and in-situ sensing to estimate cooling rates during deposition. An infrared camera captures relative melt-pool temperature, while an event-based camera provides high-temporal resolution imaging of melt-pool behavior. Experimental data are coupled with numerical analysis to extract cooling rate trends and verify model predictions. Preliminary results demonstrate the feasibility of combining simulation and event-based imaging to characterize transient thermal behavior. Compared to traditional high-speed cameras, event-based imaging offers lower data throughput while still capturing rapid thermal changes, making it a more efficient option for in-situ monitoring. This approach establishes a framework for process monitoring, providing insight into the relationship between thermal history and resulting material properties in DED-LB systems.
10:00 AM
Isotherm-Based and Heat Cycle Aware Thermal Monitoring and Prediction in Directed Energy Deposition: Sung-Heng Wu1; Ranjit Joy1; Frank Liou1; 1Missouri University of Science & Technology
Directed Energy Deposition (DED) is highly sensitive to thermal instability, which strongly influences melt pool behavior, heat accumulation, microstructural evolution, and final mechanical properties. However, existing studies primarily focus on melt pool analysis alone, providing limited understanding of overall thermal distribution and penetration behavior during multilayer deposition. This study leverages multiple cameras for comprehensive thermal monitoring and prediction in DED. A top-view infrared camera captures melt pool geometry and thermal distribution, while a side-view camera monitors heat penetration and thermal cycling behavior. Instead of analyzing only the melt pool region, isothermal segmentation at hot zone is introduced to characterize thermal distribution with improved consistency and physical interpretability. Furthermore, a data-driven feedforward prediction framework is developed to predict thermal distribution under varying process conditions, establishing deeper relationships between process parameters and spatial thermal behavior in DED.
10:20 AM
Symbolic Regression for Infrared Camera and Pyrometer Calibration in Wire-Arc Additive Manufacturing: William Werner1; Thomas Mann1; Yousub Lee2; Yukinori Yamamoto2; Bradley Jared1; 1University of Tennessee, Knoxville; 2Oak Ridge National Laboratory
Wire-arc additive manufacturing (WAAM) processes have limited capability to control the material properties of deposited material. Real-time control of microstructural evolution in WAAM-produced parts requires that transient temperature gradients within parts can be predicted from deposited heat input and measured surface temperatures. A FLIR A50 thermal camera and an Omega OS37-10-K-HIE infrared pyrometer were used to capture infrared emissions during 410SS WAAM prints for use as boundary conditions in the computational modelling of three-dimensional thermal gradients within deposited material. Calibrations for the thermal camera and pyrometer mitigating the influence of part emissivity, geometry, material, and surface condition were generated using symbolic regression in Python to relate raw infrared data and part surface temperature. Calibrated measurements from both the infrared thermal camera and infrared pyrometer were compared under various conditions. Influences of viewing angle, soot presence, surface geometry, and surface reflectivity on resultant measurements are all considered in this evaluation.
10:40 AM
Multimodal In-Situ Monitoring of Laser-Based Direct Energy Deposition: Peter Shobowale1; Oumaima Guissem1; Lars Bachert2; Amelie Schatull2; Maik Schürmann2; Jörg Seewig2; Jan Aurich2; Lennart Hinz1; Markus Kästner1; 1Leibniz University Hannover; 2RPTU Kaiserslautern
Laser-based directed energy deposition (DED-LB) is an emerging additive manufacturing technology. However, part quality is still challenged by dimensional accuracy and defect formation. While previous studies have mainly focused on monitoring the melt pool, this study investigates the less-explored post-solidification cooling phase. To characterize components during this period, we developed a multimodal sensing system combining long-wave infrared thermography and laser line triangulation. Calibrating both sensors into a unified coordinate system enabled the synchronized acquisition of 3D geometry, surface temperature distributions, and visible-spectrum imagery.A feasibility study involving nine 316L single-track deposits produced at laser powers ranging from 800 W to 1200 W examined the relationship between track geometry and thermal distributions during cooling. Initial results show that higher laser powers consistently cause elevated residual temperatures. Alongside spatial emissivity variations that correlated with darker visible-spectrum regions, an isolated thermal anomaly was observed, hinting at the system's potential sensitivity to underlying irregularities.