02.Stereolithography (NXPowerLite)
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Transcript of 02.Stereolithography (NXPowerLite)
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STEREOLITHOGRAPHY
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Other Names for Rapid Prototyping:1. ?
2. ?3. ?
4. ?
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Other Names for Rapid Prototyping:1. Additive fabrication
2. 3D printing3. Solid Free-Form Fabrication
4. Layered Manufacturing
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HISTORY:
Term stereolithography was coined in 1986 by Charles
(Chuck) W.HullStereolithography was defined as a method and apparatusfor making solid objects by successively printing thin layers
of ultraviolet curable material one layer on top of other
Hull described concentrated beam of UV light focused ontosurface of vat filled with liquid photopolymer
Light beam draws object onto surface of liquid layer by layer,causing polymerization or cross-linking to give a solid
Because of complexity of process, it must be computer-controlled
Company aiming to generalize & commercialize procedure
was founded immediately alongside invention
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First Stereolithography Machine invented by Chuck Hull
http://en.wikipedia.org/wiki/File:First_working_Stereolithography_system.jpg -
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SLA
LIQUIDS v/s SOLIDS (incl. POWDERS)
FINE DETAIL,SURFACE FINISH
Optics Laser
XY Scanner
Photosensitive
Resin
ZLASER
low power initiator
*SAFE,UNMANNED
focussed to fine spot
*EFFECT LOCALISED
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RESINS
Continuous medium - no grain or structure of
own
Minimum feature size dictated by LASER
beam-width
Parts have clean,sharply-defined boundaries
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SL & RP
ROCESS PURELY ADDITIVE ADDITIVE& SUBTRACTIVE
SUPPORTS AUTOMATIC-as needed EVERY LAYER-regardless
LIQUIDS v/s SOLIDS (incl. POWDERS)
SUPPORTS
DIRECTION VERTICAL HORIZONTAL
OF SUPPORT/ 0.010 FULL AREA
ORIENTATION in contact / adhering
PARTS VISIBLE INVISIBLEREMOVAL EASY ----
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Flow chart of RP process model to
create a 3D objectTessellation/STL Format/De-facto Std. in RP
Boundary Surfaces of object are represented by
numerous tiny triangles (similar to FEM)
Generate supports in a separate CAD file (Reasons..?
Part & support must be sliced.The part is
mathematically sectioned by computer into series of
parallel horizontal planes ,like the floors of a tall
building.Layer thickness/intended building style / cure depth/
hatch spacing/line width compensation/shrinkage
compensation.
CAD Model
Translation
Supports
Slicing
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Parts + Support + Additional parts & supports are
merged for building concurrently on the sameplatform by merging their computer
representations (models).
Select Z Wait (sec) (pause after recoating to allow
any resin surface non-uniformities to undergo
fluid-dynamic relaxation.
Merge
Prepare
BuildResin polymerization begins & a physical
3-dimensional object is created.
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Stereolithography:
Additive Layer manufacturing process
Uses vat of liquid Photo-curable Polymer / resin & UV Laserto build parts one layer at time
On each layer, laser beam traces part cross-section patternon surface of the liquid resin
Exposure to laser light cures / solidifies pattern traced onresin & adheres it to layer below
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After pattern has been traced, elevator platform descendsby single layer thickness, typically 0.05 mm to 0.15 mm
Resin-filled blade sweeps across part cross section, re-coating it with fresh material
On new liquid surface, subsequent layer pattern is traced,adhering to the previous layer
Complete 3D part is formed
After building, parts are cleaned of excess resin byimmersion in a chemical bath & then cured in UV oven
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Stereolithography:
Requires use of support structures to attach part to elevator
platform & to prevent certain geometry from not onlydeflecting due to gravity, but to also accurately hold the 2-Dcross sections in place such that they resist lateral pressurefrom the re-coater blade
Supports are generated automatically during preparation of3-D models, although they may be manipulated manually
Supports must be removed from finished product manually
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ADVANTAGES
The machine can run unattended
Accuracy is good
Good detailed parts can be built Surface finish is good (compared to bending
operations)
Transparency of Parts
Dimensional stability on parts(?)
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ADVANTAGES
SLA Prototypes can be very beneficial as they arestrong enough to be machined and can be used asmaster patterns for
Injection molding
Thermoforming
Blow molding
Various metal casting processes
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FIG
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DISADVANTAGES High overall cost (?!)
Model requires support structures & separatesupports for overhanging sections
Parts can warp (shrink non-uniformly & curl due tophase change)
Resin handling problem
Toxic material & odor
Costly installation & maintenance cost
(LASER based) Requires post- curing
Materials-only Photo Polymers
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RP MACHINE COSTS:
SLA machine can cost from ~ $100,000 to $500,000
SLA resin costs ~ $300 to $800 per gallon
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LASER
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LASER
Laser: device capable of generating narrow uniform beamof concentrated high intensity light,made up almost
completely of single pure color
Precisely directed over small or large distances
(< millimeter to > thousands of km)
Vary greatly in size ;one type is as small as a grain of
sand,another as long as a football field
Beam Intensity(?) & diameter can be rigorouslycontrolled
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USE OF LASER IN INDUSTRY
In cutting, drilling, welding & annealing
operations. (Ex.Gear tooth
induction hardening)
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USE OF LASER IN MEDICINE
In Surgery for eyes
Treating brain tumors
Dermatology & other skin treatments Orthopaedics
Neurosurgery
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USE OF LASER IN GENERAL RESEARCH
Laser beams have been bounced of moon to
determine distance from earth to moon & to
check their movements in relation to each other Lasers used to detect slightest movements of
continents, or slight movement of crust that may
be a pre-cursor to earthquake
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NOTE:
MASER & LASER are acronyms
MASER stands for Microwave
Amplification by Stimulated Emission ofRadiation
LASER stands for Light Amplification by
Stimulated Emission of Radiation
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STEREOLITHOGRAPHYStereolithography, the first of the RP process and the most widely used rapid prototyping
technology is based on the instantaneous polymerization of the photo polymer resin onexposure to laser beam (ND:YVO4). Stereolithography builds prototypes directly from 3DCAD model layer by layer by tracing the cross-section of the layer on the surface of a vat(Vat-container holding the resin) of liquid photopolymer. Once a layer is completelytraced, the building platform is lowered by a distance equal to one layer thickness andthe next layer cross section is traced by the UV laser. The self-adhesive property of the
material causes the layers to bond to one another and eventually form a complete,three-dimensional object after many such layers are formed.
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StereoLithography Build
Process CAD Design (Pro-e, I-Deas, Catia) CAD Translator (STL) STL Verification Orient Support Prepare Build Post Process
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Principle of Stereolithography
How does SL work?
Laser Beam Cures LiquidResin Layer by Layer
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On layer-by-layerbasis, starting frombottom up, lasertraces outside of eachlayer profile (hatch),then fills in area in-between (fill)
COMPLETED WHEEL(ON RAISED PLATFORM)
LASER PATH(TIMED EXPOSURE)
LIQUIDBUILD MATERIAL
PART BUILDING
(SUBMERGED IN VAT)(WHEEL)
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# RP Technology Build Material
1 Stereolithography Photosensitive
Polymer
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http://en.wikipedia.org/wiki/File:Stereolithography_apparatus.jpg -
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Specifications
SLA-7000 Laser: 354.7 nm Nd-YV04 Power at vat 800 mW
Recoating: Zephyr
Min. Layer Thickness: 0.004 in(?)
Max. part drawing speed: 140 - 525 ips
Spot size: 0.01 in - 0.03 in
Vertical resolution: 0.00004 in Build Envelope: 20 x 20 x 24 in
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SLA Applications:
FIT , FORM and FUNCTIONAL
For Conceptualization & Presentation:
Industrial Design
Tradeshows/Exhibits
Bid Packages
Marketing/Sales Presentations
Focus Studies
Package Design
Concept Models
Product Design
Design, Analysis, verification and testingDesign Verification/AnalysisDesign Iteration/OptimizationPhoto-Stress AnalysisFlow VisualizationHigh Impact
Tooling applications
ACES tooling for Injection Moulds
Investment casting patterns
Sand Casting
Spray Metal
Vacuum Casting
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SLA Applications: Tooling
SL patterns used as master
patterns to RTV mold limitedquantities of parts in urethane.
Mold:RTV and others
Qty:1-30 parts
Material(s):Urethanes
Rapid Prototype Tooling
Rapid Soft Tools using RTV
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Design verification and Assembly Mock-up
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Development of tooling using SL Prototype
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SLA Applications: Tooling
Direct ACES Injection Molding(Direct AIM) in ABS plastic
Quickly and inexpensively provides
true prototypes in actual productionmaterials
Mold:Direct AIM(ACES Injection Molding)
Qty:10-1,000Material:Thermoplastics
Rapid Bridge Tools with Direct AIM
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SLA Machine Models:
Viper
SLA 7000
Viper Pro
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Assignment:
You now know ~80% of Stereolithography
There are many videos available in Youtube
Download them, edit to make them succinct & present
http://www.aperfectworld.org/clipart/cartoons/smiley01.gif -
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Thank [email protected]
http://www.aperfectworld.org/clipart/cartoons/smiley01.gif