3 D Hardcopy Converting Virtual Reality to Physical

3 D Hardcopy: Converting Virtual Reality to Physical Models Sara Mc. Mains* U. C. Berkeley Carlo Séquin SDSC & UCSD Mike Bailey U. T. Austin Rich Crawford } *author of these slides – edited by C. H. Séquin

How Do We Make Physical Things ?

Main Types of Manufacturing • Subtractive - remove material selectively from stock. • Net shape - re-form material into new shape. • Additive - build up material in chosen locations. • Constructive - combine separately formed shapes.

Conventional Manufacturing • Subtractive – Start with simple stock – Remove unwanted volume – E. g. • Machining (NC Milling) Delcam

Conventional Manufacturing • Net shape – Start with simple stock (or powder) – Reshape in die or mold – E. g. • Forging • Molding • Casting

Manufacturing by casting, stamping, NC machining … • Appropriate for production runs – Incremental costs low • Not appropriate for small batch sizes or prototyping – Complex process planning – Special purpose tooling – Set-up costs high – Long lead times

How Do We Make Quickly Complex Prototypes ?

Conventional Manufacturing • Constructive – Combine complex sub-units – E. g. • Welding

Layered Manufacturing (LM) a. k. a. Solid Freeform Fabrication (SFF) { a. k. a. Rapid Prototyping (RP) } • Additive - build-up of complex 3 D shapes from 2. 5 D layers

Layered Manufacturing Characteristics • Perfect for prototyping • Automated process planning based on CAD model – Short lead times • No special purpose tooling • Highly complex parts economical at low production numbers

Benefits of Layers Layering the manufacturing process eliminates constraints: • No tool clearance constraints: – “Tool” is end of laser beam, – or a drop of glue. • No mold releasability constraints: – Can make overhangs and undercuts. • No fixture planning constraints: – As long as shape hangs together

Layers • 2. 5 -D slices through model – Slice interior defines part geometry – Slice complement may function as fixture and/or support

Supports: - Plan A • All complement geometry on layer serves as support, e. g. : – Same material in unbound form: (non-glued or un-fused powder). – Same material with weaker structure: (fractal-like support pillars). – Fill in with different sacrificial material: (which can be removed with solvent).

Supports: - Plan B • Supports with planned geometry – Identify overhanging features • Top-down, layer-by-layer analysis. – Selectively build supports beneath • Also layer by layer. – May use same material as for part • Less dense fractal like pillars • Loose, brittle support sheets – May use material different from part • Remove with selective solvent

LM Technologies ( Commercial – U. S. A. ) • Powder solidification – 3 D Printing (3 DP) – Selective Laser Sintering (SLS) • Additive with sacrificial supports – Stereolithography (SLA) {= Liquid solidification} – Thermoplastic deposition • Fused Deposition Modeling (FDM) • Solid Object Printing w/ Multi-Jet Modeling (MJM) • Solidscape’s Model. Maker {previously: Sanders} • “Subtractive” – Laminated Object Manufacturing (LOM)

LM Industrial Applications – Design review – Positives for molds – Functional testing

LM Medical Applications – Prosthetics – Pharmaceuticals • Micro-structure control – Tissue engineering

LM Educational Applications – Scientific Visualization – Topological Models – Tactile Mathematics San Diego Harbor (Bailey) Bailey Hyperbolic parabaloid w/ Braille annotations (Stewart Dickson) Klein Bottle Skeleton (Séquin) Séquin

LM Artistic Applications – Jewelry – Sculpture “Ora Squared” (Bathsheba Grossman)

CAD/RP Courses – Use of LM • • Scientific Parts Math Models Beautiful Artifacts Fun Stuff !