2023 Annual International Solid Freeform Fabrication Symposium (SFF Symp 2023): Applications: Process Techniques for Part Production
Program Organizers: Joseph Beaman, University of Texas at Austin
Tuesday 1:40 PM
August 15, 2023
Room: 412
Location: Hilton Austin
Session Chair: C. Hasbrouck, The Pennsylvania State University
1:40 PM
Characterizing Thermomechanical Performance of Large-format Printed Composite Polymer Structures: Tyler Corum1; Johnna O'Connell1; Maximilian Heres2; Jeff Foote2; Chad Duty1; 1University of Tennessee; 2Loci Robotics, Inc.
Large-format additive manufacturing (LFAM) is a manufacturing technique where a high volume of material is extruded in a layer-by-layer fashion to form structures that typically measure several meters in scale. The LOCI-One system is an LFAM-type system operated by Loci Robotics, Inc. that features a high throughput extruder mounted on a 6-axis robot arm. This research used the LOCI-One system to print single bead walls of 20% by weight carbon fiber reinforced acrylonitrile butadiene styrene (CF-ABS) at various layer deposition methods, print speed, layer times, and bead widths. The coefficient of thermal expansion (CTE) of the printed structures was measured to quantify effects of print conditions on thermomechanical performance. The CTE of the LFAM printed walls was measured using a large-scale digital image correlation system to characterize the distortion of the fiber reinforced composite material in the x- (print direction) and z- (between layers) directions. This study determined that with varying print parameters the CTE measured in the x-direction was largely influenced by bead geometry with the CTE measured in the z-direction relatively unaffected by either the varying parameters or the method in which layer deposition occurred.
2:00 PM
Evaluating the Compressive Strength of AM Risers for Green Sand Metalcasting: C. Hasbrouck1; Samantha Melnik1; 1The Pennsylvania State University
While many metalcasting foundries have experimented with using additive manufacturing (AM) for patternmaking, the compressive strength of the tapered AM risers for green sand metalcasting has not yet been explored. This study investigates the effects of infill pattern type, infill density, and shell thickness on the compressive strength of a standard 3-inch diameter by 5-inch tall by 3-degree taper cylindrical riser manufactured with PLA using a material extrusion process. The findings for these AM risers include plots and mathematical models of compressive strengths at three different scales of the standard geometry (full, three-quarters, and half), predicted build times and masses using other common infill patterns, potential failure mechanisms during use of AM and conventionally manufactured riser patterns, and considerations on design for both additive manufacturing and green sand metalcasting. It is concluded that AM risers can be incorporated into and perform well as part of conventional green sand metalcasting patterns.
2:20 PM
A Novel Metric for Geometric Accuracy Quantification using Point Clouds in Additive Manufacutring: Chuan He1; Sushmit Chowdhury2; Robert Bedard2; Chinedum Okwudire1; 1University of Michigan; 2Ford Motor Company
Additive manufacturing (AM) possesses a significant advantage over traditional manufacturing methods due to the complexity of parts it can produce. Nevertheless, this complexity introduces challenges in quantifying geometric errors, which significantly affect AM process quality. An automated print quality inspection framework is indispensable for differentiating the performance of various AM processes and machines, particularly in high-value applications. This study presents an approach employing the Iterative Closest Point (ICP) algorithm for registration, establishing a one-to-one correspondence between point clouds based on geometric features. A novel metric, the Similarity Score, is proposed to represent the quality of printed parts. Validated on printed parts, the Similarity Score accurately characterizes print quality with high computational efficiency. Despite the limitations of current commercial software packages and research, this approach holds potential for advancing AM error reduction and compensation strategies.
2:40 PM
An Adaptive Meshing Framework using Octree Data Structure for Voxel Based Meshes: Pradeep Chalavadi1; 1Ansys Inc.
We present an adaptive meshing framework for voxel-based meshes, designed for use in various process simulations for additive manufacturing, such as thermal, distortion, grain growth, etc. The framework uses an octree data structure to represent the meshes, and a coarsening/refinement algorithm to generate coarser and finer meshes. The algorithm preserves a 2:1 ratio of coarse to fine meshes to maintain desired accuracy. Efficient tree traversal is used for fast nodal/Gaussian solution mapping. In many cases, selective element coarsening enables the reduction of the number of nodes to be solved by the iterative matrix solver. To maintain accuracy at boundary, the algorithm can be configured to maintain a certain level of fine mesh at boundary. When part and support mesh touch, they are automatically flagged to be not combined to be coarsened at any stage. Overall, the algorithm enables reduction of solution nodes while maintaining desired accuracy at areas of interest.
3:00 PM
In-situ Defect Detection for Laser Powder Bed Fusion with Active Laser Thermography: Philipp Peter Breese1; Tina Becker1; Simon Oster1; Christian Metz2; Simon J. Altenburg1; 1Bundesanstalt für Materialforschung und -prüfung (BAM); 2THETASCAN GmbH
Defects are still common in metal components built with Additive Manufacturing (AM). Process monitoring methods for laser powder bed fusion (PBF-LB/M) are used in industry, but relationships between monitoring data and defect formation are not fully understood yet. Additionally, defects and deformations may develop with a time delay to the laser energy input. Thus, currently, the component quality is only determinable after the finished process. Here, active laser thermography, a non-destructive testing method, is adapted to PBF-LB/M, using the defocused process laser as heat source. The testing can be performed layer by layer throughout the manufacturing process. The results of the defect detection using infrared cameras are presented for a custom research PBF-LB/M machine.Our work enables a shift from post-process testing of components towards in-situ testing during the AM process. The actual component quality is evaluated in the process chamber and defects can be detected between layers.
3:20 PM
Hybrid Manufacturing: How Interleaving Processes Enables Local Control of Material Performance: Thomas Feldhausen1; Brian Post1; Kenton Fillingim1; Lauren Heinrich1; Peeyush Nandwana1; Rangasayee Kannan1; Yousub Lee1; 1Oak Ridge National Laboratory
The convergence of multiple manufacturing techniques and processing domains has enabled new uses of existing manufacturing equipment in novel workflows. For example, integration of additive and subtractive techniques by means of hybrid manufacturing has enabled manufacturers to reduce labor and material costs by mitigating disjointed processing. While these systems are more capable than single-purpose systems, the science of interleaving multiple operations is complex. A lack of fundamental understanding of factors like residual stress, microstructure evolution, and geometric distortion in these complex processes remains the primary barrier to success. However, recent work has shown that hybrid manufacturing has the potential to enable localized control of material performance characteristics. This presentation details how research into the fundamental understanding of hybrid processes is being translated to real-world applications. By covering specific developments like the world's largest metal-wire laser-directed energy deposition hybrid system and novel programming strategies, the audience will gain an appreciation of the challenges and future opportunities for hybrid additive manufacturing systems.
3:40 PM
Digital Model Generation Strategy for Printing Miniaturized Replica of Historical Cast Iron Objects - A Use Case Study: Detlev Borstell1; Barbara Friedhofen2; Dominik Kunz1; 1Koblenz University of Applied Sciences; 2Cast Iron Museum
The Cast Iron Museum at Sayn (Germany) hosts a wide range of historic cast iron objects ranging from highly detailed fly-size figures to oversize eagles and church bells. Replicating the historical cast iron, i.e. free formed objects, as miniaturized 3D prints for a new exhibition requires scanning to create the digital model. High quality of the digital model is a fundamental prerequisite for the production of the miniaturized 3D print. Size, color and surface quality of the object determine the selection of scanner and scanning method. The influence of software selection and settings during data preparation from digital photos to point cloud, mesh and finally solid is highlighted. Printing process selection is the final step in achieving the required print quality. A scanning and model generation strategy is developed using several exemplary objects from the Sayn Museum. The final print quality resulting from the selected scanning process is evaluated.
4:00 PM
Mechanical Properties of Polymer-bonded Magnets Fabricated using Magnetic Field Assisted Additive Manufacturing (MFAAM): Mandesh Khadka1; Wilhemus Geerts1; Jitendra Tate1; 1Texas State University
Magnetic Field Assisted Additive Manufacturing (MFAAM) is an additive manufacturing process that employs an external magnetic field in an extrusion-based additive manufacturing technology to fabricate polymeric magnetic structures. The traditional method of magnet fabrication, such as sintering, cannot produce magnets of complex structures. However, MFAAM can print polymer-bonded magnets with complex shapes. MFAAM can produce polymer-bonded magnets, the mechanical and magnetic properties of such magnets remain a great field to explore. In this research using MFAAM, the magnetic field was implemented during the printing of composites comprising Polyamide 12 as matrix and strontium ferrite magnetic particles as filler, at different orientations. The tensile and flexural properties are compared with neat Polyamide 12, composites printed in the magnetic field and without the magnetic field. Finally, by developing polymer-bonded magnets using MFAAM, this project achieved structures with mechanical properties like or even higher than the matrix material. This work was supported in part by NSF through DMR- MRI Grant under awards 2216440 and in part by DOD instrumentation grant (78810-W911NF-21-1-0253).