ME 290P -- October 2002 Rapid Prototyping and its Role in Product Development Carlo H. Séquin EECS Computer Science Division University of California, Berkeley

Design is an Iterative Process Formal Specifications Detailed Description Clear Concept 1st `hack' Demo Prototype Usable Evaluation Series Marketable Systems Product Vague idea Revision of artifact Experiments, get feedback

A Specific Challenge Create as soon as possible a 3D "free-form" part (not a box-like thing that can be built from flat plates) for evaluation in its application context. This includes: l visualization l tactile feedback l function verification l simulation of final use.

Conceptual Prototyping The Traditional Options: u Model from clay u Carve from wood u Bend wire meshing u Carve from styrofoam – perhaps with surface reinforcement u Mill from a block of plastic or aluminum (3- or 4-axes machines)

New Ways of Rapid Prototyping Based on Layered Manufacturing: u Build the part in a layered fashion -- typically from bottom up. u Conceptually, like stacking many tailored pieces of cardboard on top of one another. u Part geometry needs to be sliced, and the geometry of each slice determined. u Computer controlled, fully automated.

What SFF exists in COE ? In Etcheverry: u A Fused Deposition Modeling Machine u A Z-Corp Color/Mono 3D Printer In Cory Hall: u Solid Printing / Imaging (3D Systems) u Stereolithography (3D Systems) You need to prepare: u A “watertight” boundary representation with less than 100’000 triangles u In.STL format.

SFF: Fused Deposition Modeling Principle : u Beads of semi-liquid ABS * plastic get deposited by a head moving in x-y-plane. u Supports are built from a separate nozzle. Schematic view ==> u Key player: Stratasys: * acrylonitrile-butadine-styrene

Fused Deposition Modeling

Looking into the FDM Machine

Layered Fabrication of Klein Bottle Support material

Klein Bottle Skeleton (FDM)

Fused Deposition Modeling (FDM) An Informal Evaluation u Easy to use u Rugged and robust u Could have this in your office u Good transparent software (Quickslice) with multiple entry points: STL, SSL, SML u Inexpensive to operate u Slow u Think about support removal !

What Can Go Wrong ? u Black blobs u Toppled supports

SFF: Solid Imaging u Droplets of a thermoplastic material are sprayed from a moving print head onto a platform surface. u Need to build a support structures where there are overhangs / bridges. u These supports (of the same material) are given porous, fractal nature. u They need to be removed (manually). u Key player: 3D Systems:

SFF: Solid Imaging Supports made from same material, but with a fractal structure

SFF: Solid Imaging Thermojet Printer (3D Systems) u Technology: Multi-Jet Modeling (MJM) u Resolution (x,y,z): 300 x 400 x 600 DPI u Maximum Model Size: 10 x 7.5 x 8 in (13 lb) u Material: neutral, gray, black thermoplastic: l ThermoJet 88: smooth surfaces for casting l ThermoJet 2000: more durable for handling

SFF: Solid Imaging u That’s how parts emerge from the Thermojet printer u After partial removal of the supporting scaffolding

9-Story Intertwined Double Toroid Bronze investment casting from wax original made on 3D Systems’ “Thermojet”

SFF: Solid Imaging An Informal Evaluation u Fast u Inexpensive u Reliable, robust u Good for investment casting u Support removal takes some care (refrigerate model beforehand) u Thermojet 88 parts are fragile

Powder-based Approaches Key Properties: u Needs no supports that must be removed! u Uniform bed of powder acts as support. u This powder gets selectively (locally) glued (or fused) together to create the solid portions of the desired part.

SFF: 3D Printing -- Principle u Selectively deposit binder droplets onto a bed of powder to form locally solid parts. Powder SpreadingPrinting Build Feeder Powder Head

3D Printing: Some Key Players u Z Corporation: Plaster and starch powders for visualization models. u Soligen: Metal and ceramic powders for operational prototypes.

3D Printing: Z Corporation The Z402 3D Printer l Speed: 1-2 vertical inches per hour l Build Volume: 8" x 10" x 8" l Thickness: 3 to 10 mils, selectable

3D Printing: Z Corporation

u Digging out

Optional Curing: ºF Keep some powder in place <-- Tray for transport

3D Printing: Z Corporation Cleaning up in the de-powdering station

3D Printing: Z Corporation The finished part u Zcorp, u 6” diam., u 6hrs.

120 Cell -- Close-up

3D Color Printing: Z-Corporation The Z402C 3D Color Printer Differences compared to mono-color printer: l Color print head with: Cyan, Yellow, Magenta, Black, and Neutral. l Smaller build area. Specs: l Speed: vertical inches per hour l Build Volume: 6" x 6" x 6" l Thickness: 3 to 10 mils, selectable l Color depth: 80 mils

3D Color Printing: Z Corporation Use compressed air to blow out central hollow space.

3D Color Printing: Z Corporation Infiltrate Alkyl Cyanoacrylane Ester = “super-glue” to harden parts and to intensify colors.

What Can Go Wrong ? u Blocked glue lines u Crumbling parts

Broken Parts

3D Printing: Z Corporation An Informal Evaluation u Fast ! u Running expenses: moderate, (but overpriced powder) u Color print head and tubes need some care in maintenance. u Somewhat messy cleanup ! u Lot’s of dust everywhere...

SFF: Stereolithography (SLA) u UV laser beam solidifies the top layer of a photosensitive liquid. Build Stage UV Laser Beam Photopolymer

SFF: Stereolithography (SLA) SLA Machine by 3D Systems u Maximum build envelope: 350 x 350 x 400 mm in XYZ u Vertical resolution: mm u Position repeatability: ±0.005 mm u Maximum part weight: 56.8 kg

Stereolithography An Informal Evaluation u Can do intricate shapes with small holes u High precision u Moderately Fast u Photopolymer is expensive ($700/gallon) u Laser is expensive ($10’000), lasts only about 2000 hrs.

Séquin’s “Minimal Saddle Trefoil” u Stereo- lithography master

Séquin’s “Minimal Saddle Trefoil” u bronze cast, gold plated

Consumer Electronics Prototypes Role of 3D Hardcopy -- Part 1: Modeling and Prototyping u Packaging of various electronics components. u Custom designed housing for other utility products. u The physical frame for an “instrument” …

Prototyping Consumer Products “Solarcator” and “Contact-Compact” Two student-designed “products” in ME221

Model  Prototype  Mold  Part Injection-Molded Housing for ST TouchChip

Artistics Parts, Abstract Sculptures Role of 3D Hardcopy -- Part 3: Maquettes for Visualization u All-round inspection, including light and shadows. u Parts that could not be made in any other way … u Prototyping modular parts, before an injection mold is made.

“Viae Globi” Sculptures FDM maquettes of possible bronze sculptures

Sculpture Design: “Solar Arch” u branches = 4 u storeys = 11 u height = 1.55 u flange = 1.00 u thickness = 0.06 u rim_bulge = 1.00 u warp = u twist = u azimuth = u mesh_tiles = 0 u textr_tiles = 1 u detail = 8 u bounding box: u xmax= 6.01, u ymax= 1.14, u zmax= 5.55, u xmin= -7.93, u ymin= -1.14, u zmin= -8.41

Competition in Breckenridge, CO

FDM Maquette of Solar Arch  2 nd place

Which Process Should You Pick? Do you need a prototype (not just a model)?  SLS, FDM (for robustness, strength). Do you need a mold for a small batch?  SLA (for smooth, hard surface). Does part need multiple colors?  3D Color-Printing. Does part have convoluted internal spaces?  3D-P, SLS, SLA (easy support removal).

Informal Process Ratings Matrix