Additive Manufacturing File Format Hod Lipson [email protected] Chair, ASTM F42/Design Task Group on File Formats November 10, 2009 With Jonathan Hiller Join The Discussion To join the task group visit http://groups.google.com/group/stl2 Goals • • • • Identify needs of new file format Propose new standard Reach consensus Catalyze adoption Outline of presentation • Summarize survey • Outline proposed standard • Process and timetable for moving forward Survey http://www.mae.cornell.edu/lipson/stl2.htm Distribution Lists • • • • RPML SFF RM VRAP • • • • GARPA CIRP ASTM STL2 180 160 140 120 100 80 60 40 20 0 n=162 survey submissions +90 Rapid Manufacturing De Montfort University Materialise USA surface generation 3M Healthcare Delcam plc Met-L-Flo Inc Synthes (USA) 3T RPD Ltd. Delcam plc Mettis Aerospace Ltd Technical University of Catalonia A1Technologies Ltd Delft Spline Systems Mydea Technical University of Denmark A3DM Delphi Diesel Systems Mydea Technologies Texas State University- San Marcos Additive Manufacturing ResearchDesign Group Prototyping Technologies NASA Langley The Argen Corporation Advanced Laser Materials, LLC DeskArtes Oy National Institute of Standards and TheTechnology MITRE Corporation Aeronautics Institute of Technology, Direct Brazil Dimensions, Inc. National R&D Institute for Nonferrous Ticona and Rare Metals Align Technology EPFL, Switzerland National Univ. Singapore TranscenData Europe Ltd Andong natl. univ. at S. Korea ETH Zürich NAVAIR U.S. Navy APSOM INFOTEX LTD EXCELTEC netfabb GmbH Univ Texas Austin Arizona State University Fab Folk New Balance Shoe Co University of Auckland, New Zealand ASERM - AIJU fcubic NextFab Organization University of Duisburg-Essen (GER) Assa Ashuach Studio FIT North Carolina State University University of Erlangen-Nuremberg Astra Tech AB Ford Motor co Northern Lights, NRRI - UofM, Duluth University of Huddersfield Barco NV Belgium Freedom of Creation NTUT University of Louisville Bath University Fundación Prodintec Nuhill Technologies, Inc.. University of Manchester Bathsheba Sculpture LLC Georgia Tech ON DEMAND MANUFACTURING University of Maribor, Faculty of Mechanical Berenschot Government (Army) Paramount Industries University of Michigan Biomedical Modeling Inc. GPI Prototype Phonak AG University of minnesota, NRRI Boeing GRZ Software LLC POM Group, Inc. University of Twente, Netherlands BRP-Powertrain Halpin & Hines Prosthetics industry University of Washington C.R.P. Technology Hopkinson Protofacturing Group Inc. University of Wolverhampton Cambridge Consultants IET Red Bull Technology US Army Cardiff University IFW Dresden Renishaw PLC US Army RDECOM Castings Technology International Iowa State University Royal Plastic Mfg., Inc. Utah State University CCSL Iowa State University RP Department, CMRDI Institute,Utah Egypt State University Central Piedmont Community College IQS Self, UPenn, Siemens Industry VG Kunststofftechnik GmbH Chrysler, LLC and the 3DSUG ISTI - CNR - Italy Shapeways Victoria University Chrysler, LLC and the 3DSUG Laboratory DIPI, ENISE, France Shapeways VTT cirtes LAFITT S.A. Shapeways Washington State University Clemson University Las Palmas de Gran CanariaShore University Design Widgetology clonenature LEITAT, Tech.Center Solidscape, Inc. Z Corporation COPROIN LGM and CADspan Status d.o.o Z Corporation Cornell University Lockheed Martin Stratasys Zip-Bit, Inc. cstcc Loughborough University Stratasys Dalgarno Loughborough University Stratasys Inc. Chart Title Your interest in RP file format CAD software developer 9% 11% Designer/User 19% Academic/Theoretic 33% RP Service Provider 28% RP Equipment manufacturer n=246 http://www.mae.cornell.edu/lipson/stl2.htm Prioritized Features 5 4.5 4 3.5 3 2.5 2 1.5 1 n=162. Error bars = 1 Standard Deviation 5 Prioritized Features 4.5 4 3.5 3 2.5 2 1.5 1 n=162. Error bars = Standard Error Other features • • • • • • • • Main feature: keep it simple! ISO 9000-ish features like product tracking Interoperability within different manufacturers Compatible with FEA applications Identification of parent CAD program Restricted number of printings Support multiple shells Editable ASCII/Text format Other features • • • • • • • • Information about build orientation Stability/robustness No redundancy Volume validity Lock or encrypt the file with a password Ability to put a permanent 'watermark‘ Supporting geometry in native way Keep triangle mesh / No triangle mesh Existing Formats • 3D PDF – Proprietary, closed • ISO 14649 (STEP-NC) – Mostly for NC control, G-Code • STEP / IGES, SAT, Parasolid – Too complex, missing features e.g. no mesostructure • X3D VRML – Mesh, color, texture, lighting All: no provision for AM, e.g. materials, internal structure Existing Formats • PLY – 3D Scanner data • 3DS – Limited mesh size • SLC – Limited information All: no provision for AM, e.g. materials, internal structure Reaching consensus, adoption • • • • • • • • • • Non proprietary / open source Endorsement by major CAD / Manufacturers Use ASTM / Voting Backwards compatible (STL) Expandable, XML Publish for comments / discussion Open source software Conversion tools Limit the scope: Not a CAD model Make the format good Proposed Format Current STL Name • AMF – Additive Manufacturing Format – Additive Manufacturing File New format needed • Tailor to AM community needs – No content constraints • Retain Community Control – Not Proprietary • Neutral – Avoids association with existing companies XML • Meta-format: Format of formats – Text based – Easy to read/write/parse – Existing editing tools – Extensible – Highly compressible • Mentioned by a number of constituents – E.g. Materialise – Based on work by J. Hiller (Cornell) Addresses needs: Editable / Extensible / Readable / Open / Non proprietary General Concept • Part (objects) defined by regions and materials – Regions defined by triangular mesh – Materials defined by properties/names • Mesh properties can be specified – Color – Tolerance – Texture • Materials can be combined – Graded materials – Microstructure Basic Structure Addresses needs: Simple / Watertight / Backward Compatible (STL) Compressibility Need to look at dependency on # of digits Addresses needs: Small / Compressible Multiple Materials Addresses needs: Multiple Materials, No leaks between regions (shared vertices) Graded Materials Microstructure Addresses needs: Periodic meso/microstructure Material properties • By manufacturer’s name – <Name> ABS </Name> – <Name>Tango Black </Name> – <Name>Nylon 1234 </Name> • By physical property – </Property Type=“Elastic Modulus” Value=“4E9”> – </Property Type=“Poisson Ratio” Value=“1.2”> • External reference (URL) Addresses needs: Material specifications/libraries Color and Graphics • By volumetric region – Solid color • By vertex – Specify Vertex color – Specify Vertex coordinate in a bitmap Addresses needs: Color graphics Color and Graphics Tolerances • By volumetric region – Nominal tolerance – Allowed variation from original volume • By vertex – Specify point tolerance (?) – Point to point Addresses needs: Tolerance Non-meshed geometry? • Other representations are not mutually exclusive • Voxel maps – For digital/inkjet microstructure • NURBS – Add slope vectors to some triangle mesh edges – Other STEP types? • Functional Representations – implicit equations, e.g: NURBS PATCH PLANNAR PATCH NURBS PATCH PLANNAR PATCH Optionally add slope vectors to some triangle mesh edges to allow for very accurate geometry. Perfect sphere can be made with ~20 patches Print Constellation • Print orientation • Duplicated objects • Sets of different objects • Efficient nesting • Hierarchical Metadata <Metadata> <Datum ID=“Author” Data=“John Doe”></Datum> <Datum ID=“Company” Data=“…”></Datum> <Datum ID=“Description” Data=“…”></Datum> <Datum ID=“Originating CAD System” Data=“…”></Datum> <Datum ID=“Originating CAD File” Data=“…”></Datum> <Datum ID=“Comment” Data=“…”></Datum> </Metadata> Encryption <Metadata> <Datum ID=“Author” Data=“John Doe”></Datum> <Datum ID=“Company” Data=“…”></Datum> <Datum ID=“Description” Data=“…”></Datum> <Datum ID=“Comment” Data=“…”></Datum> <Datum ID=“Encryption” Data=“Prompt”></Datum> </Metadata> Key garbles vertex coordinates (e.g. using XOR); need key to un-garble Watermark / Copyright <Metadata> <Datum ID=“Author” Data=“John Doe”></Datum> <Datum ID=“Company” Data=“…”></Datum> <Datum ID=“Description” Data=“…”></Datum> <Datum ID=“Comment” Data=“…”></Datum> <Datum ID=“Copyright” Data=“Owner”></Datum> </Metadata> Copyright name garbles vertex coordinates (e.g. using XOR); copyright must be present to un-garble Other features • URL can be used in lieu of material data to allow for external libraries • Validation checksums – E.g. Original vs. actual part/region volumes • Automatic error checking – Readers/writers must check for intact topology, e.g. • All nodes referenced by at least 3 triangles • All edges referenced exactly twice per region Next steps Process 1. Initial basic format – – – – Triangle mesh Materials Colors Metadata 2. Experiment with new tags independently – – – Mesostructure Tolerances F-rep 3. Add new tags formally when mature – – Once a year With open source imlementation Process • Open source code – Slicer – Viewer – Bidirectional STL Converter • Any future feature – Requires open source implementation – BSD-Type license that allows free commercialization • Consensus – Identify liaison persons representing all major equipment manufacturers and CAD systems Optional Certification • Certified AMF readers/writers must support small set of mandatory tags – All mesh and region tags • Support of color, materials, etc not mandatory • Small suite of test cases to be validates Schedule • Draft for comments – April 1 • Draft for voting – July 1 Join The Discussion To join the task group visit http://groups.google.com/group/stl2 Bibliography • Extensible Markup Language (XML) 1.0 (Fifth Edition), W3C Recommendation 26 November 2008 http://www.w3.org/TR/REC-xml/ • Hiller, J., Lipson, H. (2009) "STL 2.0: A Proposal for a Universal MultiMaterial Additive Manufacturing File Format" Solid Freeform Fabrication Symposium (SFF'09), Aug 3-5 2009, Austin, TX, USA. • GILMAN, C. R. & ROCK, S. J. (1995) The use of STEP to integrate design and solid freeform fabrication. Solid Freeform Fabrication Symposium. Austin, TX.
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