2016 International Solid Freeform Fabrication Symposium
Permanent URI for this collectionhttps://hdl.handle.net/2152/89344
Proceedings for the 2016 International Solid Freeform Fabrication Symposium. For more information about the symposium, please see the Solid Freeform Fabrication website.
The Twenty-Seventh Annual International Solid Freeform Fabrication (SFF) Symposium – An Additive Manufacturing Conference, held at The University of Texas in Austin on August 8-10, 2016, was attended by 544 researchers from 19 countries. The number of oral and poster presentations increased to 424 this year. The meeting was held on the campus of The University of Texas at Austin in the AT&T Executive Education and Conference Center. The meeting consisted of a Monday morning plenary, 40 parallel technical sessions and a poster session.
The conference attendance is growing rapidly, clearly reflective of the interest at large in the area.
The recipient of the International Outstanding Young Researcher in Freeform and Additive Manufacturing Award was Dr. Li Yang from The University of Louisville. Dr. Brent Stucker from 3DSIM, LLC won the International Freeform and Additive Manufacturing Excellence (FAME) Award.
There are 197 papers in this conference proceedings volume. Papers marked “REVIEWED” on the first page heading were peer reviewed by two external reviewers. Papers have been placed in topical order and numbered sequentially to facilitate citation. Manuscripts for this and all preceding SFF Symposia are available for free download below and at the conference website: http://sffsymposium.engr.utexas.edu/archive.
The editors would like to thank the Organizing Committee, the session chairs, the attendees for their enthusiastic participation, and the speakers both for their significant contribution to the meeting and for the relatively prompt delivery of the manuscripts comprising this volume. We look forward to the continued close cooperation of the additive manufacturing community in organizing the Symposium. We also want to thank the Office of Naval Research (N00014-16-1-3004) and the National Science Foundation (CMMI-1639406) for supporting this meeting financially. The meeting was co-organized by The University of Connecticut at Storrs, and the Mechanical Engineering Department/Lab for Freeform Fabrication under the aegis of the Advanced Manufacturing and Design Center at The University of Texas at Austin.
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Item 2016 International Solid Freeform Fabrication Symposium Table of Contents(2016) Laboratory for Freeform Fabrication and University of Texas at AustinItem 3D Inkjetting Droplet Formation of Bacterial Cellulosic Exopolysaccharide Gel(University of Texas at Austin, 2016) Aguiar, Daniel; Albuquerque, Amanda; Li, BingbingOn-demand 3D printing of scaffolds and cell-laden structures has shown promising results that can significantly impact human welfare. The objective is to fully understand the behavior of bacterial cellulosic exopolysaccharide gel (BCEG) as a new bioink with low toxicity and high biocompatibility for regenerative medicine. Its possible application is to construct scaffolds that can be used for several biomedical applications, especially tissue engineering and treatment of critical bone defects. By using a MicroFab inkjet micro dispenser, BCEG was dispersed to create drops on demand that can be used to fabricate scaffolds. In order to fully understand the material’s behavior and droplet formation, we analyzed the physical and mechanical properties of the BCEG in different concentrations (0.1% 0.5% and 1%) and characterized it by its macroscopy, microscopy, rheology and particle size distribution.Item 3D Printing Enabled-Redistributed Manufacturing of Medical Devices(University of Texas at Austin, 2016) Munguia, J.; Honey, T.; Zhang, Y.; Drinnan, M.; Di Maria, C.; Bray, A.; Withaker, M.Recently the home-use segment of medical devices has entered in the loop of Additive Manufacturing (AM) enabled optimizations, this includes CPAP masks, insulin delivery packs and diagnostic tools such as urine-flow meters. Here we analyze the supply chain provision of a specific uroflowmetry device which is originally designed in Europe, manufactured in Asia and which has a range of distribution channels across healthcare systems. This paper analyses the impact of various AM technologies that can enable near-patient manufacture of devices on-demand. Our analysis shows that the cost of design-changes (or product updates), when reflected on the overall lifecycle cost, can be comparable to producing the device locally with a different supply chain arrangement. Furthermore it is suggested that in order to fully exploit the capabilities afforded by AM, the original product’s design features must be modified so that built-times are reduced allowing a larger 3D printing-based production capacity.Item 3D Printing in the Wild: A Preliminary Investigation of Air Quality in College Maker Spaces(University of Texas at Austin, 2016) McDonnell, Bill; Jimenez Guzman, Xavier; Dolack, Matthew; Simpson, Timothy W.; Cimbala, John M.Additive manufacturing is a popular method for prototyping and manufacturing custom parts, especially on college campuses. While there is widespread use of 3D printers as part of many engineering classwork, there is little regulation or knowledge regarding emissions. Many plastics, including polycarbonates, ABS, and PLA are known to emit high counts of volatile organic compounds (VOCs) and particulate matters (PMs). This study focuses on VOC and PM counts in several natural environments and dedicated “maker spaces” on a large college campus to gauge the exposure that students and operators experience. Emissions were measured using a photoionization detector and two particle sizers. The photoionization detector measured total VOCs, and the particle size counters measured both total nanoparticles and individual micro-particles based on relative particle diameter. Measurements were taken in hourly increments and then analyzed to determine the degree with which desktop printers emitted VOCs and PM. Our data can be used to determine whether additional ventilation or filtration is needed when 3D printing “in the wild” to enhance operator and bystander safety.Item 3D Printing of a Polymer Bioactive Glass Composite for Bone Repair(University of Texas at Austin, 2016) Murphy, C.; Kolan, K.C.R.; Long, M.; Li, W.; Leu, M.C.; Semon, J.A.; Day, D.E.A major limitation of synthetic bone repair is insufficient vascularization of the interior region of the scaffold. In this study, we investigated the 3D printing of adipose derived mesenchymal stem cells (AD-MSCs) with polycaprolactone (PCL)/bioactive glass composite in a single process. This offered a three-dimensional environment for complex and dynamic interactions that govern the cell’s behavior in vivo. Borate based bioactive (13-93B3) glass of different concentrations (10 to 50 weight %) was added to a mixture of PCL and organic solvent to make an extrudable paste. AD-MSCs suspended in Matrigel was extruded as droplets using a second syringe. Scaffolds measuring 10x10x1 mm3 in overall dimensions with a filament width of ~500 µm and pore sizes ranging from 100 to 200 µm were fabricated. Strut formability dependence on paste viscosity, scaffold integrity, and printing parameters for droplets of ADMSCs suspended in Matrigel were investigated.Item 3D Printing of Shape Changing Polymer Structures: Design and Characterization of Materials(University of Texas at Austin, 2016) Kantareddy, S.N.R.; Simpson, T.W.; Ounaies, Z.; Frecker, M.Additive manufacturing (AM) gives engineers unprecedented design and material freedom, providing the ability to 3D print polymer structures that can change shape. Many of these Shape Memory Polymer (SMP) structures require multi-material composites, and different programmed shapes can be achieved by designing and engineering these composites to fold and unfold at different rates. To enable SMP applications involving shape-changing geometries, it is important to have an understanding of the relationships between intermediate shapes and the initial and final designed shapes. To accomplish this, we investigated readily available 3D printable polymer materials and their thermo-mechanical characteristics to create multi-member structures. This paper demonstrates a way to generate different temporary geometric profiles on a single 3D printed shape with the same material. This paper also includes insights from thermo-mechanical analysis of the materials to help create multi-member shape-changing geometries using 3D printing.Item 3D Printing Technology Insertion: Sociotechnical Barriers to Adoption(University of Texas at Austin, 2016) Chang, Shawn H.; Moser, Bryan R.Since the initial development of three dimensional printing (3DP) in the 1980s, companies have relentlessly researched for applications of the technology. The potential benefit is large, beginning with improved cost and schedule to manufacture plastic and metal articles. As such, governments and industry from advanced economies continue to invest heavily to accelerate 3DP adoption. Amid advancements in the pillars of three dimensional printing – the technology, material, and software – practitioners across industries are steadily deploying 3DP in product development, prototyping, and small scale production of parts and products. However, a large gap remains between promise and the reality of larger scale adoption. The potential benefits, risks, and specific steps to adopt and realize the benefits are not clearly understood, resulting in overly zealous (at risk) or overly cautious (opportunity avoided) approaches to 3DP adoption. Traditional manufacturers rely on decades of know-how in manufacturing practices across a large portfolio of parts, making first steps on a path to adopt new processes more challenging. This paper identifies the variables that complicate or impair judgement when considering the adoption of 3DP. A systematic approach to evaluate 3DP adoption across a portfolio is needed. A methodology is proposed to analyze the relative value of 3DP at the part and product system level for prototyping and production. The outcome is a framework that combines part-level feasibility with systemic benefit of cost and schedule improvements as prototyping and production alternatives. In building this framework and in interviews with experienced manufacturers, several key insights were gained. Part by part consideration of 3DP feasibility is daunting, while adoption requires readiness not only of 3DP technology but also the receiving systems and organization. By viewing 3DP insertion as a sociotechnical system implementing the changes, attention is drawn to the tacit knowledge of critical characteristics in existing manufacturing processes, design for manufacturing decisions embedded in existing part assemblies, the pre-processing and post-processing capabilities available to shift 3DP feasibilities, and the alignment of organizational learning across parts.Item 3D-Printable Electronics - Integration of SMD Placement and Wiring into the Slicing Process for FDM Fabrication(University of Texas at Austin, 2016) Wasserfall, Florens; Ahlers, Daniel; Hendrich, Norman; Zhang, JianweiSeveral approaches to the integration of wires and electronic components into almost every existing additive fabrication process have been successfully demonstrated by a number of research groups in the last years. While the pure mechanical process of generating conductive wires inside of a printed object has proved to be feasible, the design, integration, routing and generation of toolpaths is still a laborious manual task. In this paper, we present a novel approach to place and wire SMDs in a three-dimensional object, based on schematics generated by conventional PCB design tools such as CadSoft EAGLE. Routing wires in an object for FDM manufacturing requires certain knowledge about the printer’s properties to meet the extruder characteristics, avoid non-fillable regions and electric shorts. Correspondingly for the slicing of conductive wires, the software must respect appropriate channel widths, avoid interrupted traces and ensure proper endpoints serving as contact pads for the SMDs. To fulfill those requirements, we implemented the design and routing software as a native extension of an existing slicing software. The user works in a three-dimensional representation of the final extruder toolpath, augmented by the routing information. The actual computing step is executed at the layer level by manipulating the polygons which represent the two-dimensional object topology and toolpath for each single layer, allowing the routing algorithm to avoid the generation of nonprintable traces. We successfully designed and printed some test objects including a force-sensor prototype, demonstrating a significant improvement in the usability and efficiency over manual solutions.Item 3D-Printing Graphene Oxidize Based on Directional Freezing(University of Texas at Austin, 2016) Zhang, Feng; Zhang, Qiangqiang; Grove, Weston; Lin, Dong; Zhou, ChiThis paper aims to provide a new process that is based on micro-dispensing and directional freezing to fabricate macro and micro controllable 3D graphene aerogel. In the first section, a design model of the proposed system to print 3D graphene oxide is presented, and the configurations are discussed in detail. The presented new method is contrasted to other few graphene 3D printing process. A process planning is provided includes the complete fabrication process and printing process. The physics mechanism behind the process is illustrated. A list of 2.5D and 3D printed samples are shown. Graphene Oxide solution is an easy to print material for micro-dispensing device, we successfully printed GO solutions in a stable and reliable way. Our freezing based 3D printing process matches well with freeze drying technology, which together composes the key step for fabricating truly 3D graphene aerogel.Item Additive Fabrication of 3D Structures by Holographic Lithography(University of Texas at Austin, 2016) Shusteff, Maxim; Panas, Robert M.; Henriksson, Johannes; Kelly, Brett E.; Browar, Allison E.M.As additive manufacturing (AM) technologies advance and mature, the geometric constraints imposed by fabricating 2D planar layers become increasingly important to overcome. In the realm of light-driven AM fabrication, holography provides a promising avenue toward true 3D structures. Being capable of recording and reconstructing 3D information, holographic shaping of the light field can enable direct 3D fabrication in photopolymer resins. We have conceptualized, designed, and built a prototype holographic additive micromanufacturing system, incorporating a liquid-crystal-on-silicon (LCoS) spatial light modulator (SLM) to redirect light energy at the build volume by spatial control of the phase distribution. Here we report the system design, design parameter trade-offs relevant for producing 3D structures, and initial fabrication results.Item Additive Manufacturing of Carbon Fiber and Graphene – Polymer Composites using the technique of Fused Deposition Modelling(University of Texas at Austin, 2016) Girdis, Jordan; McCaffrey, Matthew; Proust, GwénaëlleAdding micro or nano-carbon reinforcements to polymers enhances their mechanical and electrical properties. In this paper, the effects of the addition of short carbon fibres (SCF) and graphene into acrylonitrile butadiene styrene (ABS) and polylactic acid (PLA) polymer to create composite filaments for fused deposition modelling (FDM) are investigated. After creating carbon polymer composite filaments, using a commercial 3D printer, samples were printed and tested for mechanical and electrical properties. The measured values for these composites were compared to those obtained for pure ABS and pure PLA. It was found that by using only 2% SCF it was possible to achieve a 22% increase in tensile strength with no significant impact on printability. With addition of graphene, PLA was made to be conductive. These results show the feasibility of developing new materials for 3D printing that will create structurally sound and conductive designs.Item Additive Manufacturing of High Performance Semicrystalline Thermoplastics and Their Composites(University of Texas at Austin, 2016) Kishore, Vidya; Chen, Xun; Ajinjeru, Christine; Hassen, Ahmed Arabi; Lindahl, John; Failla, Jordan; Kunc, Vlastimil; Duty, ChadThis work investigates the use of two semi-crystalline high performance thermoplastics, polyphenylene sulfide (PPS) and poly (ether ketone ketone) (PEKK), as feedstock for fused filament fabrication process. Composites of PPS and PEKK are emerging as viable candidates for several components in aerospace and tooling industries and additive manufacturing of these materials can be extremely beneficial to lower manufacturing costs and lead times. However, these materials pose several challenges for extrusion and deposition due to some of their inherent properties as well as thermal and oxidative responses. To better understand the properties of such systems specific to 3D printing and determine the critical parameters that make them “printable”, various rheological and thermal properties have been studied for neat as well as short fiber reinforced PPS and PEKK systems. Attempts were also made to print these materials in a customized high temperature fused filament fabrication system.Item Additive Manufacturing of High Resolution Embedded Electronic Systems(University of Texas at Austin, 2016) Wasley, T.; Li, J.; Ta, D.; Shephard, J.; Stringer, J.; Smith, P.; Esenturk, E.; Connaughton, C.; Kay, R.Additive Manufacturing (AM) processes can facilitate the rapid iterative product development of electronic devices by optimising their design and functionality. This has been achieved by combining two additive manufacturing processes with conventional surface mount assembly to generate high resolution embedded multilayer electronic circuits contained within a 3D printed polymer part. Bottom-up DLP Stereolithography and material dispensing of isotropic conductive adhesives have been interleaved to deposit microscale features on photopolymer substrates. The material dispensing process has demonstrated the high density deposition of conductors attaining track widths of 134µm and produced interconnects suitable for directly attaching bare silicon die straight to the substrate. Interconnects down to a diameter of 149µm at a pitch of 457µm have been realized. In addition, this research developed a novel method for producing high aspect ratio z-axis connections. These were simultaneously printed with the circuit and component interconnects by depositing through-layer pillars with a maximum aspect ratio of 3.81. Finally, a method to accurately embed the packaged circuit layer within the printed part has been employed using bottom-up stereolithography.Item Additive Manufacturing Process Design(University of Texas at Austin, 2016) Clymer, Daniel; Beuth, Jack; Cagan, JonathanA current issue in metal-based additive manufacturing (AM) is achieving consistent, desired process outcomes in manufactured parts. When process outcomes such as strength, density, or precision need to meet certain specifications, these specifications can be met by changes in process variable selection. However, the changes required to achieve a better part performance may not be intuitive, particularly because process variable changes can simultaneously improve some outcomes while decreasing others. In this work, the tradeoffs between multiple process outcomes are formalized and the design problem is explored throughout the design space of process variables. User input for each process outcome is considered and the best combination of process variables is found to achieve a user’s desired outcome.Item Additively Manufactured Fasteners(University of Texas at Austin, 2016) Dressler, Amber; Scharnberg, William; Abousleiman, Anthony; Harris, Samantha; New, PhilAdditive manufacturing (AM) has reached a critical point which enables production of complex, high resolution, custom parts from robust materials. However, traditional fasteners are still use to join these complex parts together. Integrating fasteners into additively manufactured parts is beneficial for part production but there is uncertainty in their design. To understand how the fasteners fit and function, mechanical property data was collected on the prototypes. This data along with insights gained while building and testing the prototypes increased the knowledge base of design for additive manufacturing and build-to-build variability in selective laser sintering (SLS).Item Aging Behavior of Polyamide 12: Interrelation Between Bulk Characteristics and Part Properties(University of Texas at Austin, 2016) Wudy, K.; Drummer, D.The high process temperatures in combination with long building times during the laser sintering process lead to chemical and physical aging mechanisms on the polymeric feed material. The unmolten partcake material, which acts as a supporting structure, can be removed after each building process and reused for further processes. However, material as well as bulk properties are changed due to thermal and mechanical load during the laser sintering process. Within this paper the interrelation between the aging state, bulk values and resulting part properties like porosity, surface roughness and mechanical behavior are derived. Therefore, polyamide 12 powder is used for at least five processing cycles without refreshing. Before and after each building process, bulk characteristics and changes of the particle surface were determined. Specimens were manufactured during the laser sintering process in order to study the part density, roughness and mechanical behavior.Item Analyzing the Tensile, Compressive, and Flexural Properties of 3D Printed Abs P430 Plastic Based on Printing Orientation Using Fused Deposition Modeling(University of Texas at Austin, 2016) Hernandez, R.; Slaughter, D.; Whaley, D.; Tate, J.; Asiabanpour, B.To achieve the optimum functionality and mechanical properties in the AM-based parts, it is vital to fully characterize parts under static mechanical loadings (tension, compression, and flexure) that are built in different orientations. This research reports the results of the compression (ASTM standard D695), 4-point flexure (ASTM D790), and tensile (ASTM D 638 Type I) tests on the ABS plastic specimens that are designed according to the ASTM standards and are built in different orientations using the uPrint SE Plus 3D printer. This study examined the effects that printing 3D parts in different orientations (build angles) has on the mechanical properties of ABS P430 plastic. A total of 45 samples (15 tension, 15 compression, and 15 flexure) were printed in 5 orientations; 0 degrees in the XY plane, 45 degrees in the XY plane, 90 degrees in the XY plane, 45 degrees in the Z plane, and 90 degrees in the Z plane. The hypothesis was that the samples printed 0 degrees in the XY plane would be the strongest in compression and flexure, and also have the greatest modulus of elasticity. The samples printed 90 degrees in the XY plane were predicted to be the strongest in tension, having the largest tensile strength and lowest modulus of elasticity. The findings showed that printing 90 degrees in the XY plane resulted in the highest tensile strength compared to the other orientations, but not by a significant margin. Printing 0 degrees in the XY plane significantly increased the compressive and flexure strengths of the material compared to other orientations.Item Applications of 3D Topography Scanning and Multi-Material Additive Manufacturing for Facial Prosthesis Development and Production(University of Texas at Austin, 2016) Mohammed, Mazher I.; Tatineni, Joseph; Cadd, Brenton; Peart, Greg; Gibson, IanProsthetic based rehabilitation offers several advantages over surgical intervention, however, devices are generally handmade using labour intensive and subjective manufacturing techniques. We investigate the use of optical scanning to capture the surface topography from a volunteer’s facial anatomy, reconstruct this into a 3D CAD model, and from that design a patient specific prosthesis. This approach offers many advantages over existing techniques as data collection is non-intrusive, rapid and provides anatomically precise information. A CAD approach affords greater flexibility when evaluating design iterations and allows for the creation of ‘parts libraries’ for use with patients with no initial reference anatomy. The final prosthesis is realised through high resolution, multi-material 3D printing for precise model reproduction and to add functionalities such as mimicry of soft and hard tissues. Ultimately, we believe our approach provides an optimised, low-cost approach for streamlining the complete methodology for prosthesis production.Item Approaches to Geometric Data Analysis on Big Area Additively Manufactured (BAAM) Parts(University of Texas at Austin, 2016) Dreifus, G.D.; Jin, Y.; Ally, N.; Post, B.K.The promise of additive manufacturing is that a user can design and print complex geometries that are very difficult, if not impossible, to machine. The capabilities of 3D printing are restricted by a number of factors, including properties of the build material, time constraints, and geometric design restrictions. In this paper, a thorough accounting and study of the geometric restrictions that exist in the current iteration of additive manufacturing (AM) fused deposition modeling (FDM) technologies on a large scale are discussed. Offline and online methodologies for collecting data sets for qualitative analysis of large scale AM, in particular Oak Ridge National Laboratory’s (ORNL) big area additive manufacturing (BAAM) system, are summarized. In doing so, a survey of tools for designers and software developers is provided. In particular, strategies in which geometric data can be used as training sets for smarter AM technologies in the future are explained.Item Automated Lattice Optimization of Hinge Fitting with Displacement Constraint(University of Texas at Austin, 2016) Dakshnamoorthy, Vignesh; Taylor, Robert V.Additive manufacturing enables fabrication of complex lattice cell structures that are not manufacturable using conventional methods. In order to exploit this lattice capability in structural designs, the effect on structural performance must be considered. This paper uses a goose neck door hinge component to illustrate the effects of lattice structure optimization when stiffness criteria drive part design. The effect of intermediate lattice cell density parameters on resulting lattice configurations from automated lattice structure optimization are studied and it is found that the compliance of the model depends upon the range of intermediate density elements present. The paper then compares the effect of a displacement constraint on optimized weight from rib-stiffened and lattice-stiffened shell models. It is shown that optimized weight results from the lattice configuration depend on part stiffness requirements. The results show that lattice structures can be successfully implemented in weight-critical components where relaxation in the displacement constraint is acceptable.