SME's Additive Manufacturing Community is pleased to announce that the following individuals have been recognized for their contribution to additive manufacturing. The Dick Aubin Distinguished Paper Award is presented annually at SME's RAPID + TCT event.
Authors: Archish Muralidharan, Asais Uzcategui, Robert McLeod and Stephanie Bryant
Abstract: 3D printing enables integration of multiple materials with divergent properties through spatially patterned 3D-printed parts. While the spectrum of available materials affords large property variations, the interface between dissimilar materials is vulnerable to failure. The interface that forms between two materials is critical to the stability and function of a device. Hence, strategies are needed to predictably and precisely control integration. In this study, we explore integration of crosslinked polymers (hydrogels) for their widespread applications in 3D printing. The objectives were to establish a link between printing parameters to material properties to enable deterministic spatial control over integration via diffusion processes. By characterizing polymerization kinetics and mapping conversion to effective dose, it is possible to link printing parameters of light intensity and exposure time directly to conversion and ultimately to material properties of the printed resin. Applying this approach to grayscale exposures enabled spatial control over polymer mesh size, which then controls diffusion of the precursors of a second material. By precisely prescribing material properties, we demonstrate controlled integration of two heterogenous materials of different stiffness with interfacial regions that range from 10s of microns to millimeters, spatial defined patterns of integration and extended to layer-by-layer 3D printing using stereolithography.
Authors: Michael C. Chang, Sean R. Niemi, Christopher Kabb, Thomas E. Angelini, Frank J. Bova, Scott A. Banks
Abstract: The recent introduction of three-dimensional (3D) printing (also known as additive manufacturing) techniques into the field of medicine and neurosurgery has provided methods for fabricating patient-specific models for neurosurgical training, teaching, simulation, and pre-surgical planning. Soft matter technology, using a granular gel as the supporting material for 3D printing photopolymer hydrogels, now permits printing of anatomically complex models with realistic textures and tactile properties.
However, there hasn’t been a promising soft matter 3D printing system that could be used for fabricating neurosurgical patient-specific models. A major limitation is that current soft matter 3D printing technologies are unavailable to directly print these models with the same anatomical size in a timely fashion.
The aim of this project is to create a robotic soft matter 3D printing (RSM3DP) system using the soft matter 3D printing technology for fast fabrication of patient-specific models with anatomically realistic appearance and textures.
The prototype system consists of a SCARA (4-axis) robotic arm, two large-volume-closed-loop-pressure-controlled hydrogel dispensing pumps, and a high-level controller for coordinating and synchronizing the robot and the pumps. The method consists of path planning for single and multi-material 3D printing, fast motion control of the robotic arm, and precise hydrogel dispensing control. Models are directly fabricated from hydrogels extruded into the granular gel. It significantly improves the time and cost for fabricating similar sized models, making it feasible to fabricate neurosurgical anatomical models for surgeons to practice/prepare in advance of surgical cases, or for realistic teaching exercises.
Authors: T.A. Le Néel, Centrale Nantes; P. Mognol, École Normale Supérieure de Rennes; and J.Y. Hascoët, Centrale Nantes
Paper Title: Design for Additive Manufacturing: Multi Material Sand Mold (PDF)
Abstract: Indirect additive manufacturing is an alternative way to produce metal parts by using foundry practices. This paper will detail a novel method that uses the additive manufacturing process of binder jetting with different powders such as silica, aluminum, alumina and steel to create a multimaterial mold. Multimaterial, 3D-printed molds and cores can improve parts’ design freedom; this methodology gives the ability to have a specific thermal conductivity at a specific location in order to remove or displace hot spots. The reduction of hot spots enables geometries that are more complex and are said to be impossible via traditional sandcasting. A binder-jetting 3D printer was developed to additively manufacture molds and core with an inorganic binder. Simulation software indicate material’s properties and design pertinence.
Authors: Swati Chandran Thirumangalath, Scott Vader and Zachary Vader, Vader Systems
Paper Title: Liquid Metal 3D Printing: A Magnetohydrodynamic Approach (PDF)
Abstract: Liquid metal 3D printing has been of interest in the additive manufacturing industry since the 1990s because it's dramatically faster and cheaper than powder bed fusion for aluminum additive manufacturing. It is highly scalable to meet the demand for large/high-volume additive manufacturing processes. This paper describes the characteristics of the LM3DP process: Drop on-demand liquid metal printing using MagnetoJet technology (based on Magnetohydrodynamics and inkjet printing technology).
Author: Kenneth Cooper and Phillip Steele of Marshall Space Flight Center, and Bo Cheng and Kevin Chou, PhD, of the University of Alabama
Abstract: This paper elaborates the theory and implementation of heat-support structures that can reduce or eliminate overhang distortions, and yet require no or minimal post-processing for support structure removals.
Author: James Novak, Queensland College of Art Lecturer and Industrial Design PhD Candidate, Griffith University
Abstract: This paper reflects upon the development of a 3D-printed bicycle frame developed as part of the author’s university Honours project.
Author: Jason B. Jones, PhD, Hybrid Manufacturing Technologies
Abstract: Since its inception, additive manufacturing (AM) has been dominated by standalone system architectures. This has fostered implementation of AM independent from other manufacturing technologies. With mirrored myopia, the CNC world has largely been an idle spectator to the advancements in additive manufacturing of metals during the last decade.
Author: Michael Stern and Eli Cohen, MIT Lincoln Laboratory
Abstract: A low-cost, highly flexible and modular Variable AirSpeed Telescoping wing additive manufactured unmanned aerial vehicle (VAST AUAV) for atmospheric sensing is presented. A novel aerodynamic design was realized with a lightweight, efficient additive manufactured mechanical structure to meet performance requirements. The aerodynamic design features telescoping wings to permit both dash and loiter flight depending on the exposed wing area and airfoil.
Authors: E. Magalini,1 P. Robotti,1 S. Stubinger,2 B. Von Rechnberg,2 S. Ferguson,3 P. Buma,4 E. Biemond,4 and E. Preve,1 Eurocoating spa,1 University of Zürich,2 University Bern3 and Radboud University Nijmegen Medical Center4
Abstract: This paper presents some of the results obtained by Eurocoating with the help of external research partners (i.e., universities) in years of research activities performed on two specific additive manufacturing technologies used with Ti-6Al-4V: electron beam melting (EBM) or direct metal laser sintering (DMLS). In particular, the mechanical characterization of Ti-6Al-4V obtained with two technologies and in comparison with a conventional manufacturing method (i.e., wrought and annealing) is presented. Furthermore, in-vivo characterization data for several engineered trabecular highly porous surfaces suitable for bone colonization are given.
Authors: Jan T. Sehrt, Dr.-Ing., and Gerd Witt, Prof. Dr.-Ing. habil., University of Duisburg-Essen
Abstract: Today’s trend of the market requires innovative thoughts and further development of additive manufacturing processes such as beam melting. Especially with regard to the increasing diversity of different product versions with decreasing batch sizes at the same time the additive manufacturing itself becomes more and more important. In general, the additive manufacturing differs from conventional technologies by its layer wise and additive joining together material to a physical part instead of removing material. Because the trend of beam melting moves from prototype production to rapid manufacturing (production of end products with series characteristics), the identification and management of beam-melted parts can be achieved by using RFID technology. In this paper, feasibility studies for producing smart parts by the direct integration of RFID tags into beam-melted parts underneath the surface are investigated. It can be demonstrated that signals from RFID tags can be transmitted through dense metal material. This individual labeling of beam-melted parts leads to new possibilities, especially with regard to the quality management for rapid manufacturing purposes.
Authors: Philip Kilburn,1 Ian Halliday2 and Jason Watson,3 3T RPD Ltd.1,2 and Nottingham University Hospital Trust3
Abstract: Cranial bone defects following craniotomy (bone removal) arise due to trauma, tumor removal, or more commonly, decompression craniotomy. Custom-made cranial implants are often used to replace missing bone. The traditional method of using self-curing polymethylmethacrylate (PMMA) bone cement molded by hand has been updated to new methods such as the use of cobalt chrome, heat-cured PMMA, and more recently, titanium (Ti) for its biocompatible performance. This paper investigates the manufacture of cranial plates using computer tomography (CT) data, 3D CAD and direct metal laser sintering (DMLS) to reduce lead times for cranial bone implant manufacture and improve clinical outcome.
Authors: Frank Liou,1 PhD, and Mary Kinsella,2 PhD, Missouri University of Science and Technology1 and Air Force Research Laboratory, Wright-Patterson Air Force Base2
Abstract: High-performance metals, such as titanium alloys, nickel superalloys, tool steel, stainless steels, etc., can benefit from the hybrid manufacturing process described in this paper. Coupling the additive and the subtractive processes into a single workstation, the hybrid process can produce metal parts with accuracy. The surface quality of the final product is similar to the industrial milling capability. Therefore, the hybrid process is potentially a very competitive process for fabrication and repair of fully dense metallic parts with precision requirements. It will certainly impact the future rapid manufacturing industry. To achieve such a system, issues, including the understanding of the direct laser deposition process and the automated process planning of the hybrid manufacturing process, are presented.
Authors: Jayanthi Parthasarathy, Binil Starly and Shivakumar Raman, University of Oklahoma
Abstract: Cranioplasty surgical procedures that are performed to correct defects of the skull require reconstruction of both form and function. Custom implants have gained importance due to their better performance over their generic counterparts owing to their precise adaptation to the region of implantation and reduction of surgical time and better cosmesis. Recent introduction of electron beam melting (EBM) has opened a new horizon for the possibility of direct fabrication of patient specific titanium prosthesis from CT scan data. This paper will discuss the design strategy for the fabrication of craniofacial implants using EBM technology, taking into account mechanical, biological and manufacturing constraints. Finite element analysis has been used to predict the effective mechanical properties of the porous structures.
Authors: G.E. Knoppers, J. Dijkstra and W.P. van Vliet, TNO Science and Industry
Paper Title: The Design of Graded Material Objects
Abstract: Rapid manufacturing utilizes the application of different materials in parts by stacking a sequence of layers. Based on the requirements of the part, mixtures of materials, so-called functionally graded materials, can be used to compose the product functionality. This process depends completely on the availability of CAD information of the part geometry. Unfortunately, commercially available CAD systems do not allow the design of graded material structures. TNO developed a computer tool that enables the user to specify functionally graded materials. The system is based on a new approach to define the material composition at any point in the solid.
Authors: Paul Jacobs, PhD, and Thomas J. Mueller, Express Pattern Inc
Abstract: The QuickCast™ build style was first developed by 3D Systems in June 1992. The goal was to use stereolithography (SL) to rapidly fabricate a resin pattern suitable for use in the investment casting process, but which did NOT require fabrication of wax pattern tooling. The SL QuickCast pattern would then be used directly in the investment casting process, yielding a metal prototype. If the process was successful, end users could quickly proceed from a concept to a CAD model to a functional metal prototype, eliminating the time-consuming and expensive step of building wax pattern tooling.
Authors: Ryan Wicker, PhD;1 Atul Ranade;1 Francisco Medina;2 and Jeremy Palmer,3University of Texas at Austin,1 W.M. Keck Border Biomedical Manufacturing and Engineering2and Sandia National Laboratories3
Abstract: In an effort to directly manufacture unique microfluidic devices with embedded complex and three-dimensional microchannels on the order of several microns to millimeters, issues associated with microfabrication using current commercially available stereolithography technology were investigated. Practical issues associated with the successful fabrication of embedded microchannels were divided into part preparation, part manufacture and post-cleaning with emphasis on channel geometry, size, number and orientation for successful microfabrication. Build issues investigated included accurate spatial registration of the build platform, building without base support and Z-stage position accuracy during the build.
Authors: Peter Regenfuss, Lars Hartwig, Sascha Klötzer, Robby Ebert and Horst Exner, University of Applied Sciences Mittweida
Abstract: Microparts with a structural resolution of <30 µm and aspect ratios of >10 have been generated by selective laser sintering. The technique includes sintering under conditions of vacuum or reduced shield gas pressure. A novel setup and raking procedure is employed. The material is processed by a 1,064 nm Nd-YAG laser. The procedure allows the workpieces to be generated from powders of high melting metals like tungsten as well as lower melting metals such as aluminum and copper. Contingent on the parameters, the generated bodies are either firmly attached to the substrate or can be dissevered by a nondestructive method.