2003 International Solid Freeform Fabrication Symposium

Permanent URI for this collectionhttps://hdl.handle.net/2152/78319

Proceedings for the 2003 International Solid Freeform Fabrication Symposium. For more information about the symposium, please see the Solid Freeform Fabrication website.

The Fourteenth Solid Freeform Fabrication (SFF) Symposium, held at The University of Texas in Austin on August 4-6, 2003, was attended by over 100 national and international researchers from fourteen countries. Papers addressed SFF issues in computer software, machine design, materials synthesis and processing, and integrated manufacturing. The diverse domestic and foreign attendees included industrial users, SFF machine manufacturers, university researchers and representatives from the government. The Symposium organizers look forward to its being a continuing forum for technical exchange among the expanding body of researchers involved in SFF.

The Symposium was again organized in a manner to allow the multi-disciplinary nature of the SFF research to be presented coherently, with various sessions emphasizing process development, design tools, modeling and control, process parameter optimization, applications and materials. We believe that documenting the changing state of SFF art as represented by these Proceedings will serve both those presently involved in this fruitful technical area as well as new researchers and users entering the field.

This year is the first year for authors to elect to have their manuscript submissions rigorously reviewed as refereed submissions. At least two external reviewers assessed these manuscripts. Rejected manuscripts and manuscripts with mandatory revisions that were not revised have been included in the proceedings as unreviewed. There are a number of excellent manuscripts in the Proceedings for which the authors opted not to be reviewed. Reviewed manuscripts are noted as such before the paper abstract along with the date of acceptance.

The Organizing Committee held a best paper competition for the first time this year. Both oral presentations and the poster presentations were judged by at least two independent reviewers. The criteria included clarity of presentation as well as quality, significance and soundness of the research. The best oral presentation was awarded to Morgan Larsson from Arcam AB (Germany) who gave the paper “Rapid Manufacturing with Electron Beam Melting (EBM) – A Manufacturing Revolution?” The best poster presentation was awarded to Kun Dai, Xiaoxuan Li and Leon L. Shaw from the University of Connecticut-Storrs for the presentation entitled, “Comparisons Between Thermal Modeling and Experiments in Laser-Densified Dental Powder Bodies”.

The editors would like to extend a warm “Thank You” to Rosalie Foster for her detailed handling of the logistics of the meeting and the Proceedings, as well as her excellent performance as registrar and problem solver during the meeting. We are grateful to Cindy Pflughoft who helped with Proceedings production. We would like to thank the Organizing Committee, the session chairs, the attendees for their enthusiastic contributions, 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 SFF community in organizing the Symposium. We also want to thank Ralph Wachter and the Office of Naval Research (N00014-03-1-0913) for supporting this meeting financially. The meeting was co-organized by the University of Connecticut at Storrs, and the Mechanical Engineering Department, Laboratory for Freeform Fabrication and the Texas Materials Institute at The University of Texas at Austin.


Recent Submissions

Now showing 1 - 20 of 59
  • Item
    2003 International Solid Freeform Fabrication Symposium Table of Contents
    (2003) Laboratory for Freeform Fabrication and University of Texas at Austin
  • Item
    Laser Melting of Ti-Ni Shape Memory Alloy
    (2003) Kyogoku, Hideki; Ramos, Jorge A.; Bourell, David L.
    The applicability of laser melting in fabrication of Ti-Ni shape memory alloy was investigated experimentally. Elemental powders of Ti and Ni and mechanically alloyed (MA) TiNi powder were used to fabricate specimens. The effects of powder characteristics on the microstructure and shape memory characteristics of the alloy were examined. The morphology and microstructure of the laser-melted specimens were varied with fabrication conditions. Parts fabricated from elemental powders exhibited a shape memory effect, but those from MA powder did not exhibit it, although the latter showed more homogeneous microstructure than the former.
  • Item
    Direct Selective Laser Sintering of Tool Steel Powders to High Density: Part B -The Effect on Microstructural Evolution
    (2003) Akhtar, S.; Wright, C.S.; Youseffi, M.; Hauser, C.; Childs, T.H.C.; Taylor, C.M.; Baddrossamay, M.; Xie, J.; Fox, P.; O’Neill, W.
    This paper describes recent progress on the Direct Selective Laser Sintering of M2 [Fe6W-5Mo-4Cr-2V-0.8C] high speed steel (HSS) and H13 [Fe-5Cr-1V-1Si-1.5Mo-0.4C] tool steel powders. Part B will focus on the microstructural evolution of laser scanned powder beds. It has been found that H13 powders are more amenable to Direct Selective Laser Sintering than M2 powders. Densities up to 90% are possible with H13 powder compared with 70% for M2. The relationship between alloy composition, microstructure, post-scanned density and scan conditions will be discussed for single track, single layer and multi-layer constructions.
  • Item
    Direct Selective Laser Sintering of Tool Steel Powders to High Density: Part A - Effects of Laser Beam Width and Scan Strategy
    (2003) Hauser, C.; Childs, T.H.C.; Taylor, C.M.; Badrossamay, M.; Akhtar, S.; Wright, C.S.; Youseffi, M.; Kie, J.; Fox, P.; O’Neill, W.
    This paper describes progress on the Direct Selective Laser Sintering of M2 and H13 tool steel powders, comparing this with previous and further observations on stainless steel powders. The distinguishing feature is the melting of single tracks and layers in deep powder beds. The paper focuses on changing characteristics of the melt pool (mass, volume, aspect ratio, stability) and laser-powder interactivity as the laser beam width, power and scan speed change. It also compares the melt pool of neighbouring tracks during single layer construction. Simulations from a computer model to predict melt pool shape and dimension show reasonable agreement with experimental results at low scan speeds (0.5mm/s). But unexpected increases in melt depth above 1.0mm/s have been observed, suggesting higher values and more variability in laser absorptivity than expected, even approaching 1.0 for the CO2 laser radiation used in this work.
  • Item
    A Generic System for Homogenous SLS Steel Materials
    (2003) Boivie, Klas
    A generic approach to a variety if different steel materials for SLS based application has been examined. This approach is based on a base steel alloy powder mixed with a powder blend of much smaller particles. The powder blend is designed to both provide the highest possible density in the powder mass and melting material components for liquid phase sintering to full density. Furthermore, the liquid phase components in the powder blend are composed to both serve as a metallic binder for the green bodies and maintain the possibility to completely dissolve into the base material, forming a homogenous alloy. A powder blend with stainless steel base material was composed and tested and taken through the different process steps. While the formation of green bodies had limited success, to a large extent due to limitations in the process equipment, the sintering and diffusion behaviour showed promising results, both in respect to acquired densities, and homogeneity of the material.
  • Item
    Three Dimensional Printing of Tungsten Carbide-Cobalt Using a Cobalt Oxide Precursor
    (2003) Kernan, Brian D.; Sachs, Emanuel M.; Oliveria, Mark A.; Cima, Michael J.
    Tungsten Carbide 10 wt% Cobalt parts were formed by Slurry-based Three Dimensional Printing (3DPTM). The slurry contained a mixture of Tungsten Carbide and Cobalt Oxide powders, as well as dispersing and redispersing agents. The cobalt oxide is fully reduced to cobalt metal during the early stages of the sintering process. A new binder system, polyethylenimine, is described for use with powders with acidic surfaces, such as WC. Sintered densities approach the theoretical values for WC-10% Co, and the microstructures produced are similar to those of conventionally processed (press and sinter) materials. Up to four parts were produced in a single print run using a layer thickness of 25 Pm, with good dimensional agreement between them, and within the range of target dimensions after sintering.
  • Item
    Effects of Cryogenic Processing on Rapid Prototyping Materials (DSMSomos-8110 and DuraForm PA)
    (2003) Jackson, J.; Chapple, G.; Do, J.; Zhuang, X.; Bulman, J.; Foyos, J.; Mendelson, M.; Noorani, R.; Fritz, B.
    This research investigates the effects of cryogenic processing on the properties of rapid prototyped materials. Not much research has been done on the post-processing (aging) of rapid prototyped (RP) polymers at temperatures below 159K (–173˚F). Test specimens of RP thermoplastic resin DSM-Somos 8110 and DuraformPA Nylon were fabricated and cryogenically aged from 5-30 hours. The tensile strength and impact toughness were measured. The goal of this work was to study the effect of cryogenic aging on yield strength and ductility. This research investigated (1) the cryogenic aging of DSM-Somos 8110 and DuraformPA Nylon, (2) the effects of controlled ramp-downs/ups on the ultimate and tensile strengths of samples, (3) the experimental methods, and (4) the analysis and interpretation of the data.
  • Item
    Post-Processing of DuraForm� Polyamide with Small-Scale Features
    (2003) Zarringhalam, Hadi; Hopkinson, Neil
    In recent years layer manufacturing processes have evolved from Rapid Prototyping (the production of pre-production prototypes) to Rapid Manufacture (the production of end use parts) where limitations of the processes do not affect end use. There is no doubt that applications for Rapid Manufacture will grow in coming years, however there are a number of current limitations that will need to be addressed so as to maximise the scope for Rapid Manufacturing applications. One of the main limitations for the adoption of Rapid Manufacturing is material properties of the parts produced. This research has looked at the possibility of increasing the range of material properties that may be achieved from parts made using current commercial Laser Sintering systems. A series of tensile and impact test parts were built using DuraformTM powder on a 3DSystems Vanguard machine. These parts were then subjected to various form of post-processing including thermal treatment and infiltration with polymer infiltrants. The parts were subjected to tensile and impact tests with results showing that thermal post-processing achieved preferable results when compared with infiltration. Heating above the glass transition temperature yielded superior results though as the melt temperature was approached issues of deformation arose. These initial results have formed the basis for further work to consider how material properties for Rapid Manufacture by Laser Sintering may be improved.
  • Item
    Selective Laser Sintering of DuraForm Polyamide with Small-Scale Features
    (2003) Sriram, Vinay; Wood, Kristin; Bourell, David; Beaman, Joseph J.
    Selective Laser Sintering (SLS) has been used to make a fiber management module having very small feature size and ratios. Currently these modules are made out of Stereolithography using standard epoxy acrylate materials. SLS has been chosen to make these modules by the virtue of the material system it offers. The material system was chosen based on the flame retardant properties. The material used for this study is a DuraformTM Polyamide and Alumina-Ammonium Phosphate system. Ammonium Phosphate served as the binder in the Alumina-Ammonium Phosphate system. Experiments were done in order to find out the minimum feature size possible with the two material systems. Minimum hole diameters and maximum possible l/d ratios are determined by particle size, shape and processing conditions. Builds were made in different directions to understand the effect of the various processing parameters on the system. One particularly noteworthy observation was that part growth as a proportion of hole diameter became increasingly significant as hole size decreased. Optical microscopy was performed to measure the hole diameters and also to reveal the surface roughness. Results indicate material system determines the minimum diameter of micro-sized holes that can be effectively manufactured using Selective Laser Sintering.
  • Item
    Precision Extruding Deposition and Characterization of Cellular Poly-e-Caprolactone Tissue Scaffolds
    (2003) Wang, F.; Shor, L.; Darling, A.; Khalil, S.; Sun, W.; Güçeri, S.; Lau, A.
    Successes in scaffold guided tissue engineering require scaffolds to have specific macroscopic geometries and internal architectures in order to provide the needed biological and biophysical functions. Freeform fabrication provides an effective process tool to manufacture many advanced scaffolds with designed properties. This paper reports our recent study on using a novel Precision Extruding Deposition (PED) process technique to directly fabricate cellular Poly-ε-Caprolactone (PCL) scaffolds. Scaffolds with a controlled pore size of 250 µm and designed structural orientations were fabricated. The scaffold morphology, internal micro-architecture and mechanical properties were evaluated using SEM, Micro-Computed Tomography (µ-CT) and the mechanical testing. Preliminary biological study was also conducted to investigate the cell responses to the as-fabricated tissue scaffolds. The results and the characterizations demonstrate the viability of the PED process to the scaffold fabrication as well as a good mechanical property, structural integrity, controlled pore size, pore interconnectivity, and the anticipated biological compatibility of the as-fabricated PCL scaffolds.
  • Item
    Mechanics of the Selective Laser Raster-Scanning Surface Interaction
    (2003) Ramos, Jorge; Bourell, David
    In recent years, the use of a high power laser beam actuated by fast speed scanning mirrors has opened up novel selective laser raster-scan processing venues as extremely rapid motion and high overlapping of the beam can be attained. This permits distribution of laser energy precisely over geometric patterns such as rectangles, circles, triangles etc. The surface thermal history at any given point under such processing was estimated using an analytical solution for the 1D, semi-infinite, surface flux boundary condition heat conduction problem together with linear superposition theory. Presented here is the comparison of the thermal histories of different selective laser surface processes previously implemented, namely: laser surface polishing of flat surfaces, laser induced cementation of cylindrical surfaces and direct laser single layer masked deposition. It was possible to verify that in laser induced cementation, long-width and short-length scanned regions provided low average temperature and low heating rate with spaced out temperature peaks, whereas for direct laser single layer deposition in which a narrow-width – long-length region is scanned, the heating rate and peak temperature are higher and the peaks are squeezed. The analysis also provided ways to estimate the Andrew’s number associated with a raster-scan process for the sake of comparison with single-beam processes having a given number value. Understanding the influence of scan geometry and overlapping on the selective raster-scan processing provides a method to tailor the surface peak temperature as well as the heating and cooling rates, affecting the solidification or sintering conditions and therefore the mechanical properties of the parts obtained.
  • Item
    Characterization of High Alloy Steel Produced Via Electron Beam Melting
    (2003) Cormier, Denis; Harrysson, Ola; West, Harvey
    Electron Beam Melting (EBM) is a direct-to-metal freeform fabrication technique in which a 4 kW electron beam is used to melt metal powder in a layer-wise fashion. As this process is relatively new, there have not yet been any independently published studies of the high alloy steel microstructural properties. This paper describes the EBM process and presents results of microstructural analyses on H13 tool steel processed via EBM.
  • Item
    Particle Size Influence Upon Sintered Induced Strains Within 3DP� Stainless Steel Components
    (2003) Johnston, Scott; Anderson, Rhonda; Storti, Duane
    Three-dimensional printing (3DP™ 1 ) is a layer-by-layer manufacturing process whereby a three-dimensional (3D) component is created by the distribution of a liquid binder onto a powder media. A 3DP™ process using stainless steel powder as its printing media requires post-printing thermal processing for debinding and sintering of the printed green component. To minimize dimensional distortion while increasing structural integrity of the green component, 3DP™ thermal post-processing is designed to produce only neck growth between particles, defined as initial stage sintering. The accepted theoretical model governing initial stage sintering strain for spherical powder particles provides a qualitative account of strain development with respect to time and temperature variance; however, the model does not produce an accurate quantitative account for the magnitude of the strain when compared to dimensional experimental results. The theoretical model indicates that powder particle size is the dominant parameter governing sintering strain. The purpose of this study is to introduce an effective particle size into the theoretical model, thus enabling the application of the theoretical model to estimate dimensional change for components produced by 3DP™. Dimensional sintering experimentation has been performed using 3DP™ test specimens with spherical powder particles having mean diameters of 20 Pm, 80 Pm, and 200 Pm. Experimental results and progress on the theoretical model are discussed.
  • Item
    Fabrication of Laser Deposited TiC/Steel Matrix Composite Coatings
    (2003) Jiang, Wenhui; Kovacevic, Radovan
    The present work investigates the effect of laser scanning beam speeds and the content of TiC in injected powder on morphologies and microstructures of laser deposited beads of a TiC/H13 tool steel composite. The results show that the beam scanning speeds affect the size and morphology of the beads. During laser processing, TiC melts, decomposes, and subsequently, a number of fine TiC precipitates form during cooling that are uniformly distributed in the tool steel matrix. The beam scanning speeds and the amount of injected TiC exert a strong influence on the morphology and size of the fine TiC precipitates. It is believed that the precipitated TiC is the primary phase in hypereutectic Fe-TiC. Rapid cooling develops martensite with retained austenite in a steel matrix. The precipitated TiC can refine grains of the steel matrix as a solidified nucleus. TiC/H13 tool steel composite coatings with various contents of TiC were produced using the laser deposition processing technique.
  • Item
    Silicon Carbide Growth Using Laser Chemical Vapor Deposition
    (2003) Mi, Jian; Gillespie, Josh; Johnson, Ryan W.; Bondi, Scott N.; Lackey, W. Jack
    Silicon Carbide (SiC) has been grown from methyltrichlorosilane (MTS) and hydrogen using the Georgia Tech Laser Chemical Vapor Deposition (LCVD) system. A morphology study of LCVD-SiC fibers and lines was completed. Graphite and single crystal silicon were used as the substrates. In order to provide guidance to future growth of SiC, thermodynamic calculations for the C-H-Si-Cl system were performed using the SOLGASMIX-PV program.
  • Item
    Modeling and Characterization of a Novel, Low-Cost, Direct-Write Waveguide
    (2003) Mignatti, M.A.; Campbell, M.I.; Ruizpalacios, R.; Wood, K.L.; Beaman, J.J.
    Both the current long-term telecommunication trends toward optical networking and the recent growth in information bandwidth have pushed the necessity for improved optical communications. Our fabrication approach, which leverages our expertise in solid freeform fabrication in conjunction with sol-gel technology, has advantages over these other methods because of the inherent benefits of using a direct-write philosophy, such as design flexibility and minimal post-processing. However, fabrication of such novel optical components requires extensive knowledge of their light guidance capabilities. This paper will show the technical issues involved in both modeling and characterizing small optical components fabricated by locally densifying sol-gels in a modified directwrite process.
  • Item
    Laser Direct-Write of Nanoporous Optical Coatings: Preliminary Results
    (2003) Ruizpalacios, R.; Kyogoku, H.; Sriram, V.; Wood, K.L.; Beaman, J.J.
  • Item
    Instrumented Prototypes
    (2003) Shimek, M.; Lappo, K.; Wood, K.; Bourell, D.; Crawford, R.
    Full scale prototyping can be expensive and time consuming. Virtual prototypes reduce costs and time but often cannot be relied on for full scale production. Instrumented SFF prototypes update virtual prototypes, reducing cycle times and costs for full scale production. Both single and multi-layer access, two different methods for embedding sensors, are investigated at the University of Texas at Austin. Sensors are first embedded in a simulated SLS process to determine if embedding off the shelf sensors is feasible. Foil strain gages are then embedded into cantilever beams using multi-layer techniques. Both foil strain gages and bead type thermocouples are also embedded using single layer techniques. The results of the single layer tests will be used to construct a proof-of-concept prototype for single layer embedding.
  • Item
    A Study on the Manufacturing of Large Size Hollow Shape Parts for Prototype-Car Using Rapid Prototyping Technology and Vacuum Molding
    (2003) Yang, Hwa-Joon; Jang, Tae-Sik; Ryu, Choong-Ryeol; Lee, Il-Yup
    Rapid Prototyping(RP) techniques have revolutionized traditional manufacturing methods. These techniques allow the user to fabricate a part directly from a conceptual model before investing in production tooling and help develop new models with significant short time. This paper suggests the new process to manufacture large size hollow shape parts for prototype-car using Rapid Prototyping technology and Vacuum Molding with the reduction of delivery time. In addition, this paper introduces the dividing and combining method to make large size RP master model in spite of the limit of the build chamber dimensions of commercialized RP systems and post-processing method to achieve sufficient surface quality.
  • Item
    Recycling of RP Models by Solution - Casting Technique
    (2003) Prasad, K. Siva; Rathakrishnan, E.; Dhande, Sanjay G.
    Most of the Rapid Prototyping systems process polymeric materials for model making. Increased environmental concerns and waste minimization demands the recycle of these polymeric models. One way is to melt the models and cast it. However, in this method polymer degradation may occur leading to diminished functionality. In the present work a preliminary attempt has been made to reuse the polymer components by dissolving in a suitable solvent and casting the same into the required shape using soft tooling. Acrylonitrile Butadiene Styrene (ABS) polymer components, made by Fused Deposition Modeling (FDM) process were taken for the present study