2024 Annual International Solid Freeform Fabrication Symposium (SFF Symp 2024): Special Session: Metal Jetting and Droplet Deposition Processes II
Program Organizers: Joseph Beaman, University of Texas at Austin
Tuesday 8:00 AM
August 13, 2024
Room: Salon B
Location: Hilton Austin
Session Chair: Richard Hague, University of Nottingham; Negar Gilani, University of Nottingham
8:00 AM
Design and Fabrication of a Micro-Nozzle for Aerosol Jet Printing: Md Shihab Shakur1; Md Nazmus Sakib1; Erik Inman1; Srikanthan Ramesh1; 1Oklahoma State University
Aerosol jet printing is a micro-scale additive manufacturing technique that involves deposition of a polydisperse stream of aerosol through a converging nozzle. Typically, the smaller droplets in the aerosol stream tend to expand along with the gas flow and deviate from the central axis as soon as they leave the nozzle, leading to a printing defect known as overspray. In this study, we explore the feasibility of using a series of converging-diverging sections integrated into the nozzle to enhance stream collimation, improve print resolution, and minimize the occurrence of overspray. We discuss the design and fabrication of such micro-nozzles and compare their performance We discuss the design and fabrication of these micro-nozzles and compare their performance with commercially available nozzles in terms of overspray (i.e., quality) and the mean width of the printed features (i.e., resolution). Our preliminary results suggest that the proposed nozzle design is capable of yielding finer lines and significantly reducing overspray across a range of gas flow parameters. Future work will focus on optimizing the nozzle geometries and conducting a detailed analysis of the effect of nozzle design features on aerosol collimation, stream trajectories, and temporal stability.
8:20 AM
Further Developments of a Novel Low Cost Material Jetting Platform for 3D Printing: Craig Sturgess1; 1Added Scientific Ltd
Further progressing previous talks on the topic of entry level or low-cost material jetting platform this presentation goes into the detail surrounding subsystems, including control systems, ink fluid systems and the software architectures required.Presenting a cost effective solution to material jetting ink development for research organisations.
8:40 AM
Mitigating Overspray in Aerosol Jet Printing: A Deep Learning Approach for Process Optimization: Hasnaa Ouidadi1; Md Shihab Shakur2; Shubham Shah1; Shenghan Guo1; Srikanthan Ramesh2; 1Arizona State University; 2Oklahoma State University
Aerosol jet printing (AJP) is a micro-scale additive manufacturing technique for producing flexible electronics. The use of AJP for manufacturing electronics serving mission-critical needs is hindered by variability in printed features due to prevalent overspray. Overspray is the result of small droplets being deposited outside their intended area due to alterations in their trajectory. Although well-documented, understanding the origins of overspray and their relationships with process parameters is still ongoing. This study correlates morphological attributes of overspray to process parameters, establishing a basis for its mitigation. We introduce a deep learning-based method to analyze overspray type, location, and severity, relative to process parameters. A pretrained YOLO-V8 model was used to segment images of AJ-printed features to delineate regions corresponding to overspray. A correlation analysis was performed to evaluate overspray attributes relative to process parameters. Experiments involved AJ printing of conductive features with a PEDOT:PSS ink on a flexible substrate.
9:00 AM
Mechanical Performance of Lattice Structures Fabricated via Burst-Mode Drop-on-Demand Molten Metal Jetting (DoD MMJ): Paarth Mehta1; Usama Rifat1; Denis Cormier1; 1Rochester Institute of Technology
Lattice structures have been pivotal in advancing the field of lightweight and efficient material design, particularly in aerospace and automotive applications. This study explores the advanced capabilities of Drop-on-Demand Molten Metal Jetting (MMJ) for the support-free fabrication of strut-based lattice structures. The burst-mode jetting strategy involves ejecting a specific number of droplets at high frequency at the same location on a substrate, forming a larger-sized droplet. By manipulating the number of drops per burst, frequency, stepover distance, and pause time, this technique facilitates the fabrication of high strength lattice struts with varied diameters and inclination angles. Numerical simulations validated with experimental results will compare the microstructure and mechanical performance of lattices printed with varying diameters and inclination angles.
9:20 AM
Conformal Metal Additive Manufacturing Via Multi-axis Molten Metal Jetting: Kellen Traxel1; Nicholas Watkins1; Eric Elton1; Todd Weisgraber1; Andrew Pascall1; Jason Jeffries1; 1Lawrence Livermore National Laboratory
Molten metal jetting (MMJ) is an emerging metal additive manufacturing process that can print parts without the need for powder or wire feedstock that is ubiquitous in state-of-the-art metal AM techniques. Despite this advantage, MMJ is currently limited to planar printing applications using cartesian 3-axis printer designs. To this end, we report on the system design, toolpath strategies, and results from printing experiments involving non-flat metallic substrates with our custom multi-axis molten metal jetting system. We utilize planar-printing process parameters gained from previous work on printing Sn to inform toolpath strategies for use in printing on a non-flat surface, demonstrating the ability to transfer planar printing concepts into conformal printing strategies. Our work aims to increase the application space for non-powder-based metal additive manufacturing methods and applications. Prepared by LLNL under Contract DE-AC52-07NA27344. LLNL-ABS-863278.
9:40 AM Break
10:00 AM
Dissimilar Metal Bonding Using Molten Metal Jetting (MMJ): Mariusz Mika1; Paul McConville1; Priya Guggilapu1; Brendan McNamara1; Chu-Heng Liu1; Srirarm Manoharan1; Dinesh Krishna Kumar Jayabal1; 1ADDiTEC
Molten Metal Jetting (MMJ) is an economical method for producing components from a variety of aluminum (Al) alloys. This technology also enables the addition of Al alloy features to existing parts made from both similar and dissimilar materials. In this presentation, we will detail our measurement system used to evaluate the bonding quality between dissimilar materials and present data generated from these assessments.
10:20 AM
Understanding the Impact of Printing Strategies on Drop-on-Demand Molten Metal Jetting Technologies: Xiangyun Gao1; Negar Gilani1; Mark East1; Marco Simonelli1; Nesma Aboulkhair1; Richard Hague1; 1University of Nottingham
Drop-on-demand Molten Metal Jetting (DoD-MMJ) facilitates precise voxel-by-voxel deposition of metal droplets. However, this drop-on-drop deposition method may create pores between adjacent droplets, compromising printed part functionality. This study examines droplet packing strategies across various substrate temperatures to assess their impact on the physical and electrical properties of printed components. MetalJet, as a bespoke DOD-MMJ technology, is applied to print Sn at 650°C using four packing strategies across 50°C, 100°C and 150°C substrate temperatures. The effectiveness of each strategy in achieving full-density is determined through CT tomography scan analysis and the influence of the packing strategy on surface roughness and electrical conductivity is evaluated. The most effective strategies to create a full-dense part at high substrate temperatures and to mitigate challenges from residual stress at low substrate temperatures are identified. These insights are crucial for tailoring deposition strategies to specific functional requirements, thereby unlocking greater potential for future multi-material research.
10:40 AM
Molten Metal Jetting of Copper and Silver Electronic Traces: Usama Rifat1; Paarth Mehta1; Denis Cormier1; 1Rochester Institute of Technology
The additive manufacturing of printed electronic circuit patterns is typically done using conductive nanoparticle inks with Direct-Write (DW) printing processes. Although DW processes offer considerable flexibility for printing multiple materials and fine features, relatively low electrical conductivity and poor substrate adhesion are noted drawbacks of these processes. This talk will present recent advances in the use of molten metal droplet jetting (MMJ) to print solid copper and silver electronic traces that are functionally equivalent to solid core metal wires. MMJ eliminates drying and curing of nanoparticle inks, and the solidified metal's electrical conductivity matches that of the bulk material under optimized jetting conditions. Furthermore, the large cross-sectional area of the printed wires makes the traces well suited for power electronics applications involving high current.
11:00 AM
A Hybrid Aerosol Jet, Ultrasonic Spray, and Electrodeposition Approach for Additively Manufacturing Multi-layer Transformers on Magnetic Substrates: Lok-kun Tsui1; Jacob Manzi2; Thomas Hartmann2; Joshua Dye2; Judith Lavin2; 1University of New Mexico; 2Sandia National Laboratories
Planar transformers manufactured by direct write additive manufacturing on magnetic substrates are smaller, lighter weight, and more robust compared with traditional wire wound transformers. Aerosol jet printing (AJP) is a direct write AM process which can print features of 10s of µm in linewidth, but the nanoparticle inks have lower conductivity compared with bulk metal. When paired with electrodeposition of Cu and Ni onto AJP seed layers, high conductivity features can be manufactured while maintaining the resolution of AJP. Processes for AJP and ultrasonic spray of dielectric polymers were also developed as separation layers between inductors. These processes were evaluated for reproducibility, uniformity, conformal coating, and speed of processing. Finally, the electrical properties of the inductors and transformers were modeled in COMSOL and compared with experimental measurements of devices manufactured with this hybrid method. SNL is managed and operated by NTESS under DOE NNSA contract DE-NA0003525. SAND2024-04775A
11:20 AM
Minimizing Large Distortions in Binder Jetted Parts via Accurate Modeling and Compensation: Basil Paudel1; Albert To1; 1University of Pittsburgh
Binder jet parts undergo more than 15% shrinkage during sintering, a process that facilitates densification. This distortion, if not corrected, results in parts with unacceptable geometric accuracy. The current work investigates the scaling/spatial effects and proposes an approach to compensate input geometry based on mechanistic simulations and a data-driven method. A gaussian process approach is proposed to learn the deformation pattern in binder jetted parts and offset for the sintering deformation. A physics-based constitutive model is utilized to generate a training database, which is dimensionally reduced to extract the principal features. The trained model is utilized to predict the compensated part. Experimental results indicate that powder spreading process affects the green density of the fabricated parts by as much as 6-8% variation in density within the same build. The effectiveness of various corrective actions is validated both numerically and experimentally by comparing the deformed sintered shape against the target.
11:40 AM Panel Discussion