Session Sheet - 2026 Annual International Solid Freeform Fabrication Symposium (SFF Symp 2026): Control/Toolpath Pl

2026 Annual International Solid Freeform Fabrication Symposium (SFF Symp 2026): Control/Toolpath Pl
Program Organizers: David Leigh, University of Texas at Austin

Tuesday 1:30 PM
August 4, 2026
Room: Pecos
Location: AT&T Center

1:30 PM
Coordinated Motion Control for Multi-Agent Wire Arc Additive Manufacturing of Non-Gravity Aligned Multi-Directional Components: Alex Arbogast¹; Michael Sebok¹; Chris Masuo¹; William Carter¹; Andrzej Nycz¹; Patxi Fernandez-Zelaia¹; ¹Oak Ridge National Laboratory
    Multi-agent systems strengthen the production efficiency of wire arc additive manufacturing (WAAM) processes. While proof-of-concept systems have demonstrated substantial throughput gains, design complexity is often constrained to simplify multi-agent coordination and process control. This work investigates strategies for online trajectory generation and real-time coordinated motion control used within multi-agent WAAM production of multi-directional components. The framework aims to expand the range and complexity of geometries that can be manufactured using a multi-agent production process. We examine methods for generating feasible toolpath orientations within multi-directional geometries and propose a closed-loop control algorithm for regulating build geometry. A multi-agent coordinated control architecture is presented in which each agent tracks a continuously varying motion-control setpoint within a shared, dynamically changing positioner frame. The proposed control framework is experimentally validated through the production of a 1" thick hemispherical geometry using a three-robot system coordinated with a rotary-table workpiece positioner.

1:50 PM
Dynamic Layer Height Correction with Micro-Meander Tool Paths in 5-Axis Wire-DED: M. Ali Yikilmaz¹; Albert To¹; ¹University of Pittsburgh
    In Wire Arc Additive Manufacturing (WAAM), dynamically adjusting layer height usually requires altering travel speed or wire feed rates. However, fluid dynamics create a fundamental problem: forcing a taller weld bead inherently makes it wider. This leads to poor track overlapping, inconsistent geometric fidelity, and unstable heat buildup. This research presents a purely kinematic alternative. Rather than altering machine parameters, we use spatially varying "micro-meander" toolpaths to precisely control deposition volume. A custom forward-stepping algorithm dynamically adjusts the meander's amplitude and wavelength based on its exact spatial location, ensuring phase-locked, seamless track boundaries. This decouples the tool's travel speed from the actual material build-up rate, ensuring optimal arc stability and predictable thermal gradients. By maintaining constant process parameters, this approach successfully demonstrates adaptive surface planarization and variable-height deposition, effectively bypassing the physical fluid limitations of traditional WAAM.

2:10 PM
Towards Adaptive Heat Input in WAAM Processes: Steven Williams¹; Bradley Jared¹; ¹University of Tennessee
    Wire Arc Additive Manufacturing (WAAM) processes have a reputation for high material deposition rates, but the time taken to fully fabricate a part is significantly limited by heat buildup during the manufacturing process. The heat from the welding process can build up in parts produced through WAAM if sufficient methods for cooling are not utilized. Ignoring heat buildup can lead to inconsistent and often undesirable material properties. In contrast, allowing for a part to naturally cool between deposition layers may result in higher quality material deposition, but may come at a significant cost regarding time. To reduce total fabrication time while also accounting for heat accumulation, an adaptive approach is being developed in which welding parameters are modified in response to interpass temperature to reduce the time spent on cooling while also attempting to maintain high quality deposition.

2:30 PM
Vision-Based Monitoring and Feedback Control for Laser-Wire Directed Energy Deposition: Braden McLain¹; ¹Missouri University of Science and Technology
    Ideal process parameters in Laser Wire Directed Energy Deposition (LWDED) have a strong temporal and spatial dependence. Because of this, static process parameters over time will result in parts with non uniform geometry and non uniform thermal history. To account for this, it is important to implement process monitoring and control strategies. This study explores the use of visible light CMOS cameras for sensing and control in LWDED processes. Machine vision tools are developed to quantify process stability, measure deposition stickout height, and assess hotzone thermal state. Feedback control strategies are implemented for both wire stickout and meltpool area. By consolidating multiple sensing functions into a single low-cost camera system, this work aims to reduce the barrier to accessible, closed-loop control of LWDED processes.

2:50 PM
A Variable Bead Geometry Approach for Improving Conformal Slicing in Wire Arc Additive Manufacturing: Christopher Masuo¹; Alex Arbogast¹; Michael Sebok¹; William Carter¹; Andrzej Nycz¹; Patxi Fernandez-Zelaia¹; ¹Oak Ridge National Laboratory
    Conformal slicing is an advanced toolpath generation method for complex curved geometries and is applicable to wire arc additive manufacturing (WAAM). It improves local geometric uniformity and enhances surface quality and resolution by reducing stair-stepping on curved surfaces. Further improvements in reducing stair-stepping can be achieved by varying bead geometry to control material distribution across regions of changing curvature, enabling consistent layer formation. This is implemented by tagging bead segments with appropriate deposition parameters. The approach was validated on a metal inert gas (MIG) WAAM system using two case studies: a toroidal geometry fabricated with the assistance of a two-axis positioner, and a pressure-vessel dome fabricated using a non-gravity-aligned torch approach.

3:10 PM
Empirical Calibration and Slicer Implementation of Inclination-Aware Boundary Path Offsets for Wire-Fed Directed Energy Deposition: Liam White¹; Andrzej Nycz¹; Alex Arbogast¹; Chris Masuo¹; Michael Sebok¹; Alex Walters¹; William Carter¹; ¹Oak Ridge National Laboratory
    Wire-fed directed energy deposition can produce boundary-specific dimensional error when molten beads sag or spread at free edges, especially on overhanging or inclined deposition surfaces. Non-gravity-aligned torch planning expands printable overhangs, but boundary quality remains sensitive to angle-dependent melt-pool deformation, start/stop transients, and path placement. This paper presents an empirical boundary-offset calibration method for multi-bead WAAM. For a fixed material, process recipe, and torch-orientation schedule, calibration coupons are printed across selected overhang and deposition-surface angles with swept absolute offsets applied locally only to exterior and internal boundary paths. Laser scanning and sectioning quantify signed boundary error, edge-height loss, and overcorrection. These measurements define a response surface for selecting a boundary-normal offset as a function of local overhang and deposition-surface angle. The calibrated offset is implemented in a custom WAAM slicer on every layer while preserving interior bead spacing, heat input, and deposition parameters, and is validated on inclined boundary-feature coupons.