Session Sheet - 2026 Annual International Solid Freeform Fabrication Symposium (SFF Symp 2026): Metal Jetting and Droplet Deposition Processes II

2026 Annual International Solid Freeform Fabrication Symposium (SFF Symp 2026): Metal Jetting and Droplet Deposition Processes II
Program Organizers: David Leigh, University of Texas at Austin

Wednesday 8:00 AM
August 5, 2026
Room: Brazos
Location: AT&T Center

8:00 AM
Making it Snappier: Fast Pneumatic Actuation for Versatile Drop-on-demand Metal Jetting: Nicholas Watkins¹; Viktor Sukhotskiy¹; Jesse Ahlquist¹; Jason Jeffries¹; Andrew Pascall¹; ¹Lawrence Livermore National Laboratory
    Pneumatic droplet-on-demand liquid metal jetting (LMJ) provides a powder-free method of generating metal parts with a unique combination of advantages over other jetting methods: jetting feedstock of any conductivity, no moving parts contacting the molten feedstock, versatile switching between constant jetting and droplet-on-demand modes, and straightforward miniaturization for multi-nozzle jetting. However, pneumatic LMJ typically has momentum pulses that are too slow to match the capillary timescale at the nozzle, resulting in reduced jetting performance, coarser resolution, and consequently diminished part quality. We present our continued development of a fast pneumatic printhead and evaluate its performance in jetting water, tin, and bismuth droplets using a push-pull waveform. Results demonstrate improvements in resolution, jetting stability, droplet pinch-off speed, and droplet velocity while linking these enhancements in performance to underlying process physics. Prepared by LLNL under Contract DE-AC52-07NA27344. LLNL-ABS-2018960.

8:20 AM
Surface Wetting and Roughness-Aware Droplet Solidification Model for Metal-Droplet Based Additive Manufacturing: Viktor Sukhotskiy¹; Benedikt Kirchebner²; Andrew Pascall¹; ¹Lawrence Livermore National Laboratory; ²Technical University of Munich
    Droplet-based additive manufacturing methods, such as Molten Metal Jetting (MMJ), rely on effective bonding between the first deposited layer and the heated substrate. To date, CFD models have been used to understand interfacial heat transfer. Temperatures, velocities, density, and thermal conductivity of the melt remain the strongest variables that affect sequential solidification of molten droplets. Surface roughness and wetting angle are typically not considered, though empirically they have a pronounced effect. We simulate and experimentally test a model of roughness and contact angle that describes wetting and heat transfer effects of droplets impacting a rough surface, showing that the droplet bonding and solidification shape can be affected by the preparation of the surface (surface roughness) and a careful selection of the substrate material (contact angle). We use a coupled thermal-fluid simulation to test this on molten tin and propose recommendations on first-layer bonding. Prepared by LLNL under Contract DE-AC52-07NA27344. LLNL-ABS-2019010

8:40 AM
Quantifying and Optimizing Part Adhesion in Liquid Metal Jetting: Laura Marquez¹; Eric Elton¹; Viktor Sukhotskiy¹; Andrew Pascall¹; ¹Lawrence Livermore National Lab
    Liquid metal jetting requires a reliable build plate and part interface that provides sufficient adhesion during printing for part stability and heat transfer, while still allowing low-force removal after the build. This work examines adhesion behavior and build plate durability for LMJ parts printed on nickel-coated brass plates. Adhesion is quantified using a torque-based removal method under just printed, room-temperature, and quenched states, to compare how thermal history affects release behavior. Repeated printing at the same build locations is used to evaluate how adhesion changes with plate reuse and coating degradation. Surface metrology and microscopy are used to assess coating loss, surface damage, and material transfer at the part-plate interface, and these observations are related to removal behavior and interface quality. The results provide a practical framework for balancing attachment, release, and plate life in LMJ, and establish a starting point for future studies of alternative interfacial coatings.

9:00 AM
Assessment of Droplet Formation Consistency in Multi-Nozzle Molten Metal Jetting: Daniel Cormier¹; Isaac Chin¹; Denis Cormier¹; Zipeng Guo¹; ¹Rochester Institute of Technology
    Monitoring molten metal droplet characteristics through an optoelectronic sensing system shows strong potential for real-time jetting evaluation, while challenges remain in signal-to-droplet correlation and measurement repeatability under varying jetting conditions. This work presents recent progress in an optoelectronic droplet sensing framework for monitoring molten droplet consistency without fully relying on high-speed imaging approaches. A collimated light source and silicon photodiode are used to capture transient droplet signals for evaluating droplet size, velocity, and trajectory behavior. The study also investigates methods to improve signal fidelity and data interpretation through an improved illumination scheme, a high-resolution imaging reference, and comparative analysis across different sensing modalities. The presentation will discuss the signal acquisition architecture, data processing workflow, and approaches for interpreting jetting consistency across different operating conditions. Preliminary results demonstrate the capability of the sensing approach to distinguish droplet formation characteristics and detect variations in jetting stability.

9:20 AM
In-Situ Surface Modification in Molten Metal Jetting: Gabriel Stash¹; David Trauernicht¹; Denis Cormier¹; ¹Rochester Institute of Technology
    Drop-on-Demand (DoD) Molten Metal Jetting (MMJ) is a promising additive manufacturing technique capable of high throughput and fine feature resolution. However, like other metal additive technologies, MMJ parts have a textured surface finish which can negatively affect mechanical properties and necessitate post-processing. We propose a novel in-situ surface modification method in which an external tool manipulates deposited molten metal droplets as they solidify at the part boundary. This continuous engagement during solidification yields a smoother surface, reducing post-processing requirements and improving as-built part quality. Preliminary results show that this approach considerably reduced as-built surface roughness in flat samples and has demonstrated promising surface modification in more complex geometries. We further discuss strategies for tool development and toolpath implementation to enable processing of arbitrary shapes.