Rapid Prototyping

1. Advanced Manufacturing
Choices
MAE 156-256
Spring 2012, Dr. Marc Madou
Class 9: Rapid Prototyping
By Dr. Marc Madou

2. Two Ways for Fabrication:
Subtractive manufacturing Additive 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
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:
• Prototyping (90 %)
– 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 1 week Polycarbonat
e TrueForm
SandForm
light: 100%;
margin:
0">Casting
Patterns
Concept Models
Stereolithography
250 (SLA)
$33/hr 2 weeks Epoxy Resin
(Translucent)
Thin walls
Durable Models
Z402 3-D
Modeller (Jet)
$27.50/hr 1 week Starch/Wax Concept Models

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 24.00 x 36.00
in.
Min feature
size:
0.005 in.
Min layer
thickness:
0.0050 in.
Accuracy: 0.0050 in.
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:
– FAB@Home
– 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)
• FAB@Home • 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