CS 294-12 -- October 2002

1. CS 294-12 -- October 2002 Rapid Prototyping and its Role in Design Realization Carlo H. Séquin EECS Computer Science Division University of California, Berkeley

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

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

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

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

6. 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: • visualization • tactile feedback • function verification • simulation of final use.

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

8. “Hyperbolic Hexagon II” (wood) Brent Collins

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

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

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

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

13. Profiled Slice through the Sculpture • One thick slicethru “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, 3/4of one board.

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

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

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

17. “Heptoroid” • Collaboration byBrent Collins &Carlo Séquin(1997)

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

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

20. Fused Deposition Modeling

21. Looking into the FDM Machine

22. Zooming into the FDM Machine

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

24. Layered Fabrication of Klein Bottle Support material

25. Klein Bottle Skeleton (FDM)

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

27. What Can Go Wrong ? • Black blobs • Toppled supports

28. Solid Object Printing ModelMaker II (Solidscape)

29. SFF: Solid Object Printing ModelMaker II (Solidscape) • Alternate Deposition / Planarization Steps • Build envelope: 12 x 6 x 8.5 in. • Build layer: 0.0005 in. to 0.0030 in. • Achievable accuracy: +/- 0.001 in. per inch • Surface finish: 32-63 micro-inches (RMS) • Minimum feature size: 0.010 in. • Key Player:Solidscape*: http://www.solid-scape.com/ * formerly: Sanders

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

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

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

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

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

35. SFF: Solid Imaging • That’s how partsemerge from theThermojet printer • After partial removalof the supportingscaffolding

36. 9-Story Intertwined Double Toroid Bronze investment casting fromwax original made on3D Systems’“Thermojet”

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

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

39. SFF: 3D Printing -- Principle • Selectively depositbinder dropletsonto abed of powderto form locallysolid parts. Head Powder Spreading Printing Powder Feeder Build

40. 3D Printing: Some Key Players • Z Corporation: http://www.zcorp.com/Plaster and starch powders for visualization models. • Soligen: http://www.zcorp.com/Metal and ceramic powdersfor operational prototypes. • Therics Inc.:http://www.therics.com/Biopharmaceutical products,tissue engineering.

41. 3D Printing:Z Corporation The Z402 3D Printer • Speed: 1-2 vertical inches per hour • Build Volume: 8" x 10" x 8" • Thickness: 3 to 10 mils, selectable

42. 3D Printing:Z Corporation

43. 3D Printing:Z Corporation • Digging out

44. Optional Curing: 30 min. @ 200ºF Keep some powder in place <-- Tray for transport

45. 3D Printing:Z Corporation Cleaning up in the de-powdering station

46. 3D Printing:Z Corporation The finished part • Zcorp, • 6” diam., • 6hrs.

47. 120 Cell -- Close-up

48. 3D Color Printing: Z Corporation The Z402C 3D Color Printer Differences compared to mono-color printer: • Color print head with: Cyan, Yellow, Magenta, Black, and Neutral. • Smaller build area. Specs: • Speed: 0.33 - 0.66 vertical inches per hour • Build Volume: 6" x 6" x 6" • Thickness: 3 to 10 mils, selectable • Color depth: 80 mils

49. 3D Color Printing: Z Corporation

50. 3D Color Printing: Z Corporation Use compressed air to blow out central hollow space.