Additive Manufacturing File Format Hod Lipson [email protected] Chair, ASTM F42/Design Task...
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Transcript of Additive Manufacturing File Format Hod Lipson [email protected] Chair, ASTM F42/Design Task...
Additive Manufacturing File Format
Chair, ASTM F42/Design Task Group on File FormatsNovember 10, 2009
With Jonathan Hiller
Join The Discussion
http://groups.google.com/group/stl2 To join the task group visit
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
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n=162 survey submissions
+90 Rapid Manufacturing De Montfort University Materialise USA surface generation3M Healthcare Delcam plc Met-L-Flo Inc Synthes (USA)3T RPD Ltd. Delcam plc Mettis Aerospace Ltd Technical University of CataloniaA1Technologies Ltd Delft Spline Systems Mydea Technical University of DenmarkA3DM Delphi Diesel Systems Mydea Technologies Texas State University- San MarcosAdditive Manufacturing Research GroupDesign Prototyping TechnologiesNASA Langley The Argen CorporationAdvanced Laser Materials, LLC DeskArtes Oy National Institute of Standards and TechnologyThe MITRE CorporationAeronautics Institute of Technology, BrazilDirect Dimensions, Inc. National R&D Institute for Nonferrous and Rare MetalsTiconaAlign Technology EPFL, Switzerland National Univ. Singapore TranscenData Europe LtdAndong natl. univ. at S. Korea ETH Zürich NAVAIR U.S. NavyAPSOM INFOTEX LTD EXCELTEC netfabb GmbH Univ Texas AustinArizona State University Fab Folk New Balance Shoe Co University of Auckland, New ZealandASERM - AIJU fcubic NextFab Organization University of Duisburg-Essen (GER)Assa Ashuach Studio FIT North Carolina State University University of Erlangen-NurembergAstra Tech AB Ford Motor co Northern Lights, NRRI - UofM, DuluthUniversity of HuddersfieldBarco NV Belgium Freedom of Creation NTUT University of LouisvilleBath University Fundación Prodintec Nuhill Technologies, Inc.. University of ManchesterBathsheba Sculpture LLC Georgia Tech ON DEMAND MANUFACTURINGUniversity of Maribor, Faculty of Mechanical Engineering, SloveniaBerenschot Government (Army) Paramount Industries University of MichiganBiomedical Modeling Inc. GPI Prototype Phonak AG University of minnesota, NRRIBoeing GRZ Software LLC POM Group, Inc. University of Twente, NetherlandsBRP-Powertrain Halpin & Hines Prosthetics industry University of WashingtonC.R.P. Technology Hopkinson Protofacturing Group Inc. University of WolverhamptonCambridge Consultants IET Red Bull Technology US ArmyCardiff University IFW Dresden Renishaw PLC US Army RDECOMCastings Technology InternationalIowa State University Royal Plastic Mfg., Inc. Utah State UniversityCCSL Iowa State University RP Department, CMRDI Institute, EgyptUtah State UniversityCentral Piedmont Community CollegeIQS Self, UPenn, Siemens Industry VG Kunststofftechnik GmbHChrysler, LLC and the 3DSUG ISTI - CNR - Italy Shapeways Victoria UniversityChrysler, LLC and the 3DSUG Laboratory DIPI, ENISE, FranceShapeways VTTcirtes LAFITT S.A. Shapeways Washington State UniversityClemson University Las Palmas de Gran Canaria UniversityShore Design Widgetologyclonenature LEITAT, Tech.Center Solidscape, Inc. Z CorporationCOPROIN LGM and CADspan Status d.o.o Z CorporationCornell University Lockheed Martin Stratasys Zip-Bit, Inc.cstcc Loughborough University StratasysDalgarno Loughborough University Stratasys Inc.
Your interest in RP file format
11%
33%
28%
19%
9%
Chart Title
CAD software developer
Designer/User
Academic/Theoretic
RP Service Provider
RP Equipment manufacturer
n=246
http://www.mae.cornell.edu/lipson/stl2.htm
Prioritized Features
1
1.5
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2.5
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3.5
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4.5
5
n=162. Error bars = 1 Standard Deviation
Prioritized Features
1
1.5
2
2.5
3
3.5
4
4.5
5
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
Addresses needs: Small / Compressible
Need to look at dependency on # of digits
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 PATCHPLANNAR PATCH
NURBS PATCHPLANNAR 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
Process1. 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
http://groups.google.com/group/stl2 To join the task group visit
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 Multi-
Material 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.