Additive Manufacturing File Format Hod Lipson Hod lipsoncornell

  • Slides: 49
Download presentation
Additive Manufacturing File Format Hod Lipson Hod. lipson@cornell. edu Chair, ASTM F 42/Design Task

Additive Manufacturing File Format Hod Lipson Hod. lipson@cornell. edu Chair, ASTM F 42/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/stl 2

Join The Discussion To join the task group visit http: //groups. google. com/group/stl 2

Goals • • Identify needs of new file format Propose new standard Reach consensus

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

Outline of presentation • Summarize survey • Outline proposed standard • Process and timetable for moving forward

Survey

Survey

http: //www. mae. cornell. edu/lipson/stl 2. htm

http: //www. mae. cornell. edu/lipson/stl 2. htm

Distribution Lists • • RPML SFF RM VRAP • • GARPA CIRP ASTM STL

Distribution Lists • • RPML SFF RM VRAP • • GARPA CIRP ASTM STL 2

n=162 survey submissions

n=162 survey submissions

Your interest in RP file format n=246

Your interest in RP file format n=246

http: //www. mae. cornell. edu/lipson/stl 2. htm

http: //www. mae. cornell. edu/lipson/stl 2. htm

Prioritized Features n=162. Error bars = 1 Standard Deviation

Prioritized Features n=162. Error bars = 1 Standard Deviation

Prioritized Features n=162. Error bars = Standard Error

Prioritized Features n=162. Error bars = Standard Error

Other features • • Main feature: keep it simple! ISO 9000 -ish features like

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

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 • 3 D PDF – Proprietary, closed • ISO 14649 (STEP-NC) –

Existing Formats • 3 D 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 • X 3 D VRML – Mesh, color, texture, lighting All: no provision for AM, e. g. materials, internal structure

Existing Formats • PLY – 3 D Scanner data • 3 DS – Limited

Existing Formats • PLY – 3 D Scanner data • 3 DS – 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

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

Proposed Format

Current STL

Current STL

Name • AMF – Additive Manufacturing Format – Additive Manufacturing File

Name • AMF – Additive Manufacturing Format – Additive Manufacturing File

New format needed • Tailor to AM community needs – No content constraints •

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 –

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

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)

Basic Structure Addresses needs: Simple / Watertight / Backward Compatible (STL)

Compressibility Need to look at dependency on # of digits Addresses needs: Small /

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)

Multiple Materials Addresses needs: Multiple Materials, No leaks between regions (shared vertices)

Graded Materials

Graded Materials

Microstructure Addresses needs: Periodic meso/microstructure

Microstructure Addresses needs: Periodic meso/microstructure

Material properties • By manufacturer’s name – <Name> ABS </Name> – <Name>Tango Black </Name>

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=“ 4 E 9”> – </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 –

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

Color and Graphics

Tolerances • By volumetric region – Nominal tolerance – Allowed variation from original volume

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

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 Optionally add slope vectors to some triangle mesh edges to

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 •

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

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”

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>

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

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

Next steps

Process 1. Initial basic format – – Triangle mesh Materials Colors Metadata 2. Experiment

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 •

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 –

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

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/stl 2

Join The Discussion To join the task group visit http: //groups. google. com/group/stl 2

Bibliography • Extensible Markup Language (XML) 1. 0 (Fifth Edition), W 3 C Recommendation

Bibliography • Extensible Markup Language (XML) 1. 0 (Fifth Edition), W 3 C Recommendation 26 November 2008 http: //www. w 3. 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.