Rapid Prototyping by Layered Manufacturing

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Rapid Prototyping by Layered Manufacturing
Product Realization Cycle ? Mock-Ups, Engg
prototypes
Why speed up prototyping? Quick product
entry into market ?captive market. Lower
operating costs of development group Longer
PRP time ? higher reluctance of managers to
change existing
technologies ?
causes stagnation of products
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Rapid Prototyping
Rapid prototyping quick fabrication of
geometric shape possibly use different materials
than designed materials possibly use different
process than production process
Uses of prototype models 1. Aesthetic
Visualization 2. Form-fit-and-function
testing 3. Casting models
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Layered Manufacturing Processes
Stereolithography
Selective Laser Sintering
Laminated Object Manufacturing (LOM)
Fused Deposition Modeling
Three Dimensional Printing (MIT ? ZCorp)
Laser Engineered Net Shaping
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Stereolithography (SLA)
1. Raw material viscous resin 2. Part
constructed in layers of thickness t 3.
Supporting platform ? in container at depth t 3.
UV laser solidifies part cross-section 4.
Platform lowered by t 5. Part cross-section
computed at current height t 6. Repeat Steps 4,
5 7. Removed completed part, 8. Break off
supporting structures 9. Cure the part in oven.
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SLA companies and applications
Companies that develop and sell SLA machines 1.
3D Systems Inc. (www.3Dsystems.com) 2. Aaroflex
Inc (www.aaroflex.com)
Shower head
Automobile Manifold (Rover)
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Selective Laser Sintering (SLS)
1. Deposit layer of powder on platform. 2. The
CO2 laser solidifies part cross-section 3. Lower
platform by t 4. Deposit new layer of powder
above previous layer 5. Repeat steps 2-4 to
complete part 5. Shake away surrounding powder
(re-used) 6. Bake model in oven to sinter
(melting point d) 7. Diffuse lower MP metal to
fill pores
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SLS companies and applications
First commercialized by Prof Carl Deckard (UT
Austin) Marketed by DTM Corp. DTM acquired by
3Dsystems Inc. 1. 3D Systems Inc.
(www.3Dsystems.com) 2. EOS GmbH, Munich, Germany.
Metal mold using SLS, injection molded parts
Plastic parts using SLS
both examples, source DTM inc.
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Fused Deposition Modeling (FDM)
? Part constructed by deposition of melted
plastic 1. A 0.05 wire of plastic pulled from
a spool into head 2. Plastic is melted (1ºF over
MP) 3. Molten plastic extruded through the pen
nozzle to build layer
Materials ABS, Polycarbonate (PC), Polyphenylsulf
onen (PPSF)
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FDM companies and applications
FDM is a patented technology of Stratasys Inc.
Gear assembly Toy design using FDM models of
different colors
Monkey Cinquefoil Designed by Prof Carlo Sequin,
UC Berkeley 5 monkey-saddles closed into a single
edged toroidal ring
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Laminated Object Modeling (LOM)
1. Paper is pulled across the table 2. Laser beam
cuts the outline of the part, plus removal
grids 3. A large, fixed size rectangle
surrounding the part is also cut. 4. The table is
lowered by t ( paper thickness) 5. Fresh paper
rolled on top of the previous layer 6. Laser cuts
new layer 7. A heated roller activates glue to
stick the fresh layer 8. Repeat steps 4-7 to
complete part 9. Break away removal blocks
to get final part
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LOM companies, applications
Original technology developed by Helisys
Inc. Helisys acquired by Corum. 1. Cubic
Technologies Inc www.cubictechnologies.com 2.
KIRA Corp, Japan www.kiracorp.co.jp
source Corum Inc
source KIRA corporation
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3D printing
Technology invented at MIT, Part constructed with
starch powder 1. Layer of powder spread on
platform 2. Ink-jet printer head deposits drops
of water/glue on part cross-section 3. Table
lowered by layer thickness 4. New layer of powder
deposited above previous layer 5. Repeat steps
2-4 till part is built 6. Shake powder to get part
Materials used starch, plaster-ceramic powder
Multi-colored water can be used to make
arbitrary colored parts (same as ink-jet printing)
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3D Printing companies, applications
1. Z-corporation www.zcorp.com 2. Soligen
www.soligen.com
Engine manifold for GM racing car Cast after
Direct Shell Production Casting source
www.soligen.com
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Laser Engineered Net Shaping (LENS)
Technology invented at Sandia Labs, USA, Part
constructed with metal powder 1. High power
laser melts site of deposition 1. Powder
deposited by nozzle into hot-spot 2. Laser builds
cross-section in raster-scan fashion 3. Table
lowered by layer thickness 4. New layer
constructed on top of previous layer 5. Repeat
process till build is complete
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LENS companies, applications
1. Optomec Inc, USA www.optomec.com
source www.optomec.com
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Rapid Prototyping Model and Software
Repeated cross-section operations ? 3D CAD model
is required Cross-section of complex surfaces ?
computationally slow Typical LM process surface
accuracy is low (10-50m) ? Approximation model
is used STL models
STL models Triangulated, surface models
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STL format
All commercial CAD systems can convert 3D models
? STL User specifies accuracy Higher accuracy
? many, small triangles ? large files
STL Rules 1. Surface of arbitrary (finite) genus
? object can have holes 2. Multiple shells are
allowed (assemblies) 3. Surface must be closed 4.
Vertex-to-vertex rule
WRONG
CORRECT
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Rapid Prototyping by Layered Manufacturing
The ASCII STL File Format Solid name facet
normal nx ny nz outer loop vertex
v1x v1y v1z vertex v2x v2y v2z
vertex v3x v3y v3z endloop endfacet e
ndsolid name
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Remarks
About STL STL is de facto standard for all RP
technologies ASCII STL files are LARGE, Binary
format is more compact
About LM Expensive, but gaining
popularity First popular technique
SLA Currently (2006) most popular FDM