CS October 2002 Rapid Prototyping and its Role in Design Realization Carlo H. Séquin EECS Computer Science Division University of California, Berkeley

Focus of Talk u How can we use the visualization power offered by computer graphics and by computer-controlled rapid prototyping in design and in design realization?

DESIGN The following questions should be raised and be answerable: u What is the purpose of the artifact ? u What are the designer’s goals for it ? u How will the artifact be evaluated ? u What are the associated costs ? u How can we maximize the benefit / cost ratio ?

Example Task “Design an Instrument as an Interface to an Existing Data Base. u Purpose: Enhance access to data base. u Goals: Provide: novel insights, deeper understanding, better user interface. u Evaluation: Let several users use the device and observe what emerges. u Costs: Fabrication, as well as operation. u Optimization: Heavily dependent on approach taken.

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)

“Hyperbolic Hexagon II” (wood) Brent Collins

Brent Collins’ Prototyping Process Armature for the "Hyperbolic Heptagon" Mockup for the "Saddle Trefoil" Time-consuming ! (1-3 weeks)

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.

Slices through “Minimal Trefoil” 50%10%23%30% 45%5%20%27% 35%2%15%25%

“Heptoroid” ( from Sculpture Generator I ) Cross-eye stereo pair

Profiled Slice through the Sculpture u One thick slice thru “Heptoroid” from which Brent can cut boards and assemble a rough shape. Traces represent: top and bottom, as well as cuts at 1/4, 1/2, 3/4 of one board.

Emergence of the “Heptoroid” (1) Assembly of the precut boards

Emergence of the “Heptoroid” (2) Forming a continuous smooth edge

Emergence of the “Heptoroid” (3) Thinning the structure and smoothing the surface

“Heptoroid” u Collaboration by Brent Collins & Carlo Séquin (1997)

Some Commercial Processes Additive Methods with Sacrificial Supports: u Fused Deposition Modeling (Stratasys) u Solidscape (Sanders Prototype, Inc.) u Solid Printing / Imaging (3D Systems) u Stereolithography Powder-Bed Based Approaches: u 3D Printing (Z-Corporation) u Selective Laser Sintering

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

Zooming into the FDM Machine

Single-thread Figure-8 Klein Bottle As it comes out of the FDM machine

Layered Fabrication of Klein Bottle Support material

Klein Bottle Skeleton (FDM)

Fused Deposition Modeling 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

Solid Object Printing ModelMaker II (Solidscape)

SFF: Solid Object Printing ModelMaker II (Solidscape) u Alternate Deposition / Planarization Steps l Build envelope: 12 x 6 x 8.5 in. l Build layer: in. to in. l Achievable accuracy: +/ in. per inch l Surface finish: micro-inches (RMS) l Minimum feature size: in. u Key Player: Solidscape*: * formerly: Sanders

SFF: Solid Object Printing Projection of 4D 120-cell, made in “jewelers wax.” (2” diam.)

SFF: Solid Scape (Sanders) An Informal Evaluation u The most precise SFF machine around u Very slow u Sensitive to ambient temperature u Must be kept running most of the time u Poor software u Little access to operational parameters Based on comments by B. G.:

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. u Therics Inc.: Biopharmaceutical products, tissue engineering.

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

Minimal Trefoils -- cast and finished by Steve Reinmuth

What Can SFF Be Used For?

Use of 3D Hardcopy What is 3D Hardcopy good for? (cont.) u Consumer Electronics Design Prototypes ==> touch and feel ! u Mathematical & Topoplogical Models ==> visualization and understanding u Artistics Parts & Abstract Sculptures ==> all-round visual inspection, including light and shadows. My goal is to inspire you to put these SFF technologies to new and intriguing uses.

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

Geometrical / Topoplogical Models Role of 3D Hardcopy -- Part 2: Visualization of objects, when 2D is not quite enough. u Self-intersecting surfaces. u Projections of 4-D polytopes.

Single-thread Figure-8 Klein Bottle Modeling with SLIDE

Triply-Twisted Figure-8 Klein Bottle FDM, 9” diam.6 days

Projections of Reg. 4D Polytopes 4D Cross-Polytope

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.

Family of Scherk-Collins Trefoils

“Viae Globi” Sculptures FDM maquettes of possible bronze sculptures

Brent Collins at Bridges 2000

Photos by Brent Collins

Collin’s Construction Description SWEEP CURVE (FOR DOUBLE CYLINDER) IS COMPOSED OF 4 IDENTICAL SEGMENTS, FOLLOWS THE SURFACE OF A SPHERE.

Reconstruction / Analysis (v1) AWKWARD ALIGNMENT FROM THE FDM MACHINE

Further Explorations (v2: add twist)

A More Complex Design (v3)

Verification with 3D Model (v4) GALAPAGOS-4

Fine-tuned Final(?) Version (v5)

Galapagos-6 in the Making

Galapagos-6 (v6)

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

We Can Try Again … in L.A.

“Whirled White Web” u Design for the 2003 International Snow Sculpture Championship Breckenridge, CO, Jan.28 – Feb.2

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

The Most Challenging SFF Part 3 rd -order 3D Hilbert Curve: u much weight u much length u no supports u only two tube- connections between the two halves.

Informal Process Ratings Matrix

How Can You Get Access to SFF ? We have under our control: u A Fused Deposition Modeling Machine u A Z-Corp Color/Mono 3D Printer You need to prepare: u A “watertight” boundary representation with less than 100’000 triangles u In.STL format.