2024 Annual International Solid Freeform Fabrication Symposium (SFF Symp 2024): Process Development: Vat Polymerization
Program Organizers: Joseph Beaman, University of Texas at Austin
Wednesday 8:00 AM
August 14, 2024
Room: 616 AB
Location: Hilton Austin
Session Chair: David Bourell, University of Texas
8:00 AM
Optical Expansion of Projection-based 3D Printing: Brian Lee1; Minsung Kim1; 1Sungkyunkwan University
This study explores the application of the infinity-corrected optical system (ICOS) to projection-based 3D printing technology to enhance print area without sacrificing the print resolution. Traditional 3D printer systems utilize finite optical elements that limit the print area due inversely proportional relationship between the print resolution and print area. ICOS, by contrast, employs a configuration that allows for an extended optical path by using parallel beams, which can incorporate additional optical components like mirrors and beam splitters, enhancing functionality. This arrangement facilitates the expansion of UV patterns over larger areas while maintaining high resolution. Experimental comparisons of illuminated image qualities between transmitted and reflected patterns demonstrate a negligible variance, suggesting effective scalability for mass production. A single UV light engine with ICOS can achieve the performance of multiple UV projectors, offering a cost-effective solution for large-scale manufacturing. Further research could vastly impact the future capabilities of 3D printing in industry.
8:20 AM
An Automated Vat Photopolymerization Process for Composite Parts with Multiple Spatially Steered Continuous Fibers: Vivek Khatua1; G. K. Ananthasuresh1; B. Gurumoorthy1; 1Indian Institute of Science
Fiber-reinforced polymer composite parts with continuous fibers embedded along bespoke spatial paths for a specific mechanical loading are shown to have superior stiffness and strength. We had presented a vat photopolymerization-based machine that can steer a single fiber along a spatial path within the layer-by-layer process. Here, we report an advancement that automates simultaneous spatial steering of multiple fibers. For this, we use permanent magnets that hold and steer the fibers in different directions with actuation provided by a cylindrical array of electromagnets. The method, machine, and process of actuating electromagnets along with the 3D-printed composite parts are presented.
8:40 AM
3D-Printing by Patterning and Advancing a Liquid Photo-Polymer Film: Vivek Khatua1; G. K. Ananthasuresh1; B. Gurumoorthy1; 1Indian Institute of Science
We present an additive manufacturing process, which uses the surface tension of a photo-polymer resin to suspend a film across a wide aperture and curing a pattern on the film. A horizontal film is made by dipping and raising an aperture from a shallow pool of resin and the film is polymerized selectively with a 405 nm laser. After each step of selective curing with a pattern, the build plate is moved backwards to advance the part. This process consumes a much smaller amount of resin as compared to a bottom-up vat photopolymerization machine. This paper presents the proof of concept of the process along with the machine and two parts printed using this process. Furthermore, the paper discusses the effect of process parameters such as pressure on the suspended film, and an extension of the process to a continuous interface polymerization. The process presented has the potential for in-situ additive manufacturing including 3D-printing in micro-gravity for space applications.
9:00 AM
Initial Layer Characterization for Multilayer Fluid Interface Supported Printing: Balaji Alagar1; Siva Appana1; Brody Oliver1; Stacy Ross1; Christian Sims1; Yongxin Wu1; Amit Jariwala1; 1Georgia Institute of Technology
A new technique for top-down Stereolithography (SLA) 3D printing that reduces the need for sacrificial supports is in development. SLA is a popular form of additive manufacturing, which leverages photocurable resin but requires sacrificial support structures for overhanging geometry. Sacrificial supports consume excess time and material, require extraneous post-processing, and reduce overall surface quality. To negate the need for additional support, a fluid interface supported printer (FISP) is being developed. The FISP prints from a thin resin layer above a static, immiscible supporting fluid. Density differences between the support fluid and cured resin prevent deflection from buoyant and gravitational forces. Printing a first layer without a solid support plate presents numerous challenges. Creating a uniform first layer will lay the foundation for more complex multilayer curing. Thus, the current research is directed at improving print quality through experimentation and multiphysics simulation.
9:20 AM
Development of a Testing Platform for High-viscosity Photopolymers: Martha Leach1; Roxana Carbonell1; Hongtao Song1; Carolyn Seepersad1; 1Georgia Institute of Technology
There has been increasing demand in recent years for additively manufactured elastomers with mechanical properties similar to commercially available molded silicones. Polydimethylsiloxane (PDMS) is a silicone rubber known for its exceptional mechanical properties and biocompatibility. UV-curable PDMS resins have been developed for vat photopolymerization (VPP), but the addition of silica nanoparticles is necessary to approach the mechanical properties of molded silicones. These reinforcement particles greatly increase the viscosity of the resin, making conventional VPP techniques unsuitable. This work details the development of a desktop top-down VPP system with selective laser sintering (SLS)-style recoating for high-viscosity resins. This printer will serve as a testbed for new formulations of PDMS resins and other high-viscosity photopolymers. It will also facilitate the validation of soft robots that have been optimized for use with existing PDMS resins.
9:40 AM
Use of an Acousto-Optic Deflector Light Engine to Improve Resolution and Speed of the Stereolithography Process: Kaya Bayazitoglu1; Tim Phillips1; Joseph Beaman1; Arthur Paolella2; Carrigan Braun2; James Ottaway2; Chris Corey2; Joe Dodd2; Nick Alban2; 1University of Texas Austin; 2L3Harris Technologies
In stereolithography (SLA) additive manufacturing (AM), a laser system creates part geometries using galvanometric mirrors and field lenses to locally polymerize raw materials. Small features require smaller laser spot sizes to achieve sufficient resolution and accuracy, while larger parts require longer scan times. The use of an acousto-optic deflector (AOD) to significantly reduce the time delay resolving the re-aiming of the laser to each disparate polymerization coordinate well below that of a galvo-system may allow for an increase in both speed and resolution of the SLA process. The use of an AOD to raster perpendicular to the regular galvo scan line enables the use of dynamic beam-shaping with smaller spot sizes while avoiding cure-through problems associated with the gaussian beam shape.