1. Advanced Manufacturing Choices
MAE
Spring 2012, Dr. Marc Madou
Class 9: Rapid Prototyping
By Dr. Marc Madou

2. Two Ways for Fabrication:
Additive Manufacturing
Subtractive manufacturing

3. Rapid Prototyping Some other names: Additive manufacturing
Computer controlled moldless additive manufacturing
Part is produced by producing multiple “slices” i.e. cross sections
From 3D model [STL file (see next slide)] to physical object, with a “click”
Layered manufacturing
Rapid prototyping:
Variety of methods: more and more functional products rather than just prototypes

4. STL File*
The STL (stereo lithography) file format is supported by many other software packages; it is widely used for rapid prototyping and computer-aided manufacturing (CAM). STL files describe only the surface geometry of a three dimensional object without any representation of color, texture or other common CAD model attributes.
*An STL file describes a raw unstructured triangulated surface by the unit normal and vertices (ordered by the right-hand rule) of the triangles using a three-dimensional Cartesian coordinate system.

5. Basic Principles of Rapid Prototyping
3d model generated
Sliced
Each slice manufactured and layers are fused together
A voxel (volumetric pixel or, more correctly, Volumetric Picture Element) is a volume element, representing a value on a regular grid in three dimensional space. This is analogous to a pixel, which represents 2D image data in a bitmap (which is sometimes referred to as a pixmap).

6. Materials For Rapid Prototyping
Materials covered:
Thermoplastics (FDM, SLS)
Thermosets (SLA)
Powder based composites (3D printing)
Metals (EBM, SLS)
Sealant tapes (LOM)
Stereolitography (SLA)
Selective Laser Sintering (SLS)
Fused Deposition Modeling (FDM)
Laminated Object Modeling (LOM)
3D Printing
Electron Beam Melting (EBM)

7. Examples of Rapid Prototyping Applications:
Concept models
Architectural models
Disney characters
Movies—or is that real and thus manufactured?
Etc
Manufacturing (10%)
Implants and custom medical devices
Aerospace parts
Pilot scale production of lab equipment
Molds .. A Stradivarius ?

8. Rapid Prototyping by Industry Sectors:

9. Methods for RP Stereolitography (SLA) Selective Laser Sintering (SLS)
Fused Deposition Modeling (FDM)
Laminated Object Modeling (LOM)
3D Printing
Electron Beam Melting (EBM)

10. Selection of Optimal Process
Functional parts:
FDM (ABS and nylon)
SLS (thermoplastics, metals)
EBM (high strength alloys, Ti, stainless steel, CoCr)
Non functional parts:
SLA: smoothest surface, good for casting
LOM, 3D Printing, marketing and concept protos.

11. Rapid Prototyping Techniques:
Machine
Cost
Response Time
Material
Application
Fused Deposition Modeler 1600 (FDM)
$10/hr
2 weeks
ABS or Casting Wax
Strong Parts
Casting Patterns
Laminated Object Manufacturing (LOM)
$18/hr
1 week
Paper (wood-like)
Larger Parts
Concept Models
Sanders Model Maker 2 (Jet)
$3.30/hr
5 weeks
Wax
Casting Pattern
Selective Laser Sintering 2000 (SLS)
$44/hr
Polycarbonate TrueForm
SandForm
light: 100%; margin: 0">Casting Patterns
Stereolithography 250 (SLA)
$33/hr
Epoxy Resin (Translucent)
Thin walls
Durable Models
Z402 3-D Modeller (Jet)
$27.50/hr
Starch/Wax

12. Process: Laminated Object Modeling (LOM)
Object made by deposition and cutting of layers of tapes
Introduced in 1991 by Helisys Inc of Torrance.
Cubic and Helisys offer this technology
Slow, sharp edges
Research on composites prepregnated moldless manufacturing
Inexpensive depending on accuracy, large scale models possible
Slow and inaccurate (knives vs lasers)

13. LOM Objects

14. Fused Deposition Modeling (FDM)
Extruder on a cartesian robot
Extrudes thermoplast polymers “spaghetti”
Moderately fast and inexpensive
Stratasys is the market leader
Functional parts, ABS and nylon
Best choice for mechanical engineers and product developers !
Can be used for direct digital manufacturing
Systems starting from $14,000

15. FDM Abbreviation: FDM Material type: Solid (Filaments) Materials:
Thermoplastics such as ABS, Polycarbonate, and Polyphenylsulfone; Elastomers
Max part size (LxWxH):
36.00 x x in.
Min feature size:
0.005 in.
Min layer thickness:
in.
Accuracy:
Surface finish:
Rough
Build speed:
Slow

16. Most common FDM Systems
High Res:
Dimension ELITE
Large FootPrint (12x12)
Dimension SST1200
Low cost
uPrint ($14,900)
Do it Yourself:
RepRap

17. Stereolitography (SLA)
Patented in 1986
3D System is the market leader
Highest resolution and smoothness
UV Laser beam cure cross-sections of parts in a liquid batch of photoreactive resin
Subvariants: DLP entire layer projection

18. Stereolitography (SLA)

19. Selective Laser Sintering (SLS)
Can be used for both thermoplastics and metal
Powder is fed into a continuous layer
Laser is used to fuse/sinter powder particles layer-by-layer
Produces functional parts
Layer thickness 0.004” or less

20. SLS samples

21. 3D Printing Layer of powder is first spread across build area
Inkjet-like printing of binder over the part cross-section
Repetition of the process with the next layer
Can produce multi-colored parts
Useful only for presentation media
Lowest resolution of all techniques
Market Leader: Z-Corp

22. 3D Printing

23. Electron Beam Melting (EBM)
Dispensed metal powder in layers
Cross-section molten in a high vacuum with a focused electron beam
Process repeated until part is completed
Stainless steel, Titanium, Tungsten parts
Ideal for medical implants and injection molds
Still very expensive process

24. Examples of EBM

25. Do it Yourself FDM rapid prototyping (cost under $5K)
RepRap

26. The Future ? Self-replication !
RepRap achieved self-replication at 14:00 hours UTC on 29 May 2008 at Bath University in the UK. The machine that did it - RepRap Version 1.0 “Darwin” - can be built now - see the Make RepRap Darwin link there or on the left, and for ways to get the bits and pieces you need, see the Obtaining Parts link.

27. Questions and Answers ?

28. Rapid Prototyping Process Flow
Solid Modelling
Tesselation/Generation of STL file
Support Generation
“Slicing” of the Model
Model Physical Buildup
Cleanup and Post Curing
Surface Finishing