3D Hardcopy: Converting Virtual Reality to Physical Models Sara McMains* Carlo Séquin Mike Bailey Rich Crawford U.C. Berkeley } U.T. Austin SDSC & UCSD *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 3D shapes from 2.5D 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 –3D Printing (3DP) –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 ModelMaker {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 Hyperbolic parabaloid w/ Braille annotations (Stewart Dickson) Séquin Klein Bottle Skeleton (Séquin) San Diego Harbor Bailey (Bailey)

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

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