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CH2 CH2 STEREOLITHOGRAPSTEREOLITHOGRAP

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StereoLithography (SL) is the first process StereoLithography (SL) is the first process ever developed in rapid prototyping field ever developed in rapid prototyping field with the meaning of 3-dimensional with the meaning of 3-dimensional printing. Charles Hull developed and printing. Charles Hull developed and patented the completed system in 1986. patented the completed system in 1986. Then he founded 3D Systems, inc. to Then he founded 3D Systems, inc. to develop commercial applications of the develop commercial applications of the process. process. Stereolithography builds plastic parts or objects a layer at a time by tracing a laser beam on the surface of a vat of liquid photopolymer. This class of materials originally developed for the printing and packaging industries, quickly solidifies wherever the laser beam strikes the surface of the liquid

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PROCESSPROCESS Stereolithography uses additive fabrication Stereolithography uses additive fabrication

method where a UV-sensitive photopolymer method where a UV-sensitive photopolymer resin is cured by a laser to build parts a layer resin is cured by a laser to build parts a layer at a time. at a time.

Parts are traced by the laser beam on the Parts are traced by the laser beam on the surface of the photopolymer, causing it to cure surface of the photopolymer, causing it to cure and solidify the prototype layer. and solidify the prototype layer.

After each layer has been traced, the build After each layer has been traced, the build platform lowers the part by a single layer platform lowers the part by a single layer thickness, typically 0.002" to 0.006", and thickness, typically 0.002" to 0.006", and sweeps a blade filled with photopolymer sweeps a blade filled with photopolymer ("resin") across the part to deposit fresh SLA ("resin") across the part to deposit fresh SLA Resin.Resin.

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PROCESSPROCESS

This creates a new surface for the part This creates a new surface for the part and a subsequent layer is traced, and a subsequent layer is traced, fusing it to the previous layer. fusing it to the previous layer.

After each layer is built the Prototype After each layer is built the Prototype is ready for post-processing and excess is ready for post-processing and excess resin is removed using a solvent such resin is removed using a solvent such as alcohol and cured using a uv light as alcohol and cured using a uv light source. source.

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PROCESS PARAMETERSPROCESS PARAMETERSSLA SLA 250/50HR250/50HR

SLA 3500SLA 3500 SLA5000SLA5000 SLA7000SLA7000

Laser type, Laser type, wavelength, wavelength, powerpower

HeCd,325nmHeCd,325nm,,

6mW6mW

Solid state Solid state Nd:YVONd:YVO4 4

354.7nm 354.7nm 160mW160mW

Solid state Solid state frequency frequency tripled tripled Nd:YVONd:YVO44 354.7nm 354.7nm 216mW216mW

Solid state Solid state frequency frequency tripled tripled Nd:YVONd:YVO44 354.7nm 354.7nm 800mW800mW

Layer Layer thicknessthickness

mmmm

0.0625-0.10.0625-0.1 0.05-0.10.05-0.1 0.05-0.10.05-0.1 0.0254-0.1270.0254-0.127

Beam Beam diameter mmdiameter mm

0.06-00.080.06-00.08 0.20-0.300.20-0.30 0.20-0.300.20-0.30 0.23-0.28 to 0.23-0.28 to 0.685-0.8380.685-0.838

Drawing Drawing speedspeed

635 mm/s635 mm/s 3.45 m/s3.45 m/s Up to 5.0 m/sUp to 5.0 m/s 2.54-9.52 2.54-9.52 m/sm/s

Max part Max part weight,weight,

KgKg

9.19.1 56.856.8 68.0468.04 68.0468.04

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PROCESS PARAMETERSPROCESS PARAMETERSElevator Elevator resolution resolution and and repeatabilitrepeatability mmy mm

0.00250.0025 0.00177,+/- 0.00177,+/- 0.0050.005

0.00177,+/- 0.00177,+/- 0.0130.013

0.001,+/- 0.001,+/- 0.0010.001

Vat Vat capacity,Lcapacity,L

32.232.2 99.399.3 253.6253.6 253.6253.6

Max build Max build envelop ,menvelop ,mmm

250 x 250 x 250 x 250 x 250250

350 x 350 x 350 x 350 x 400400

508 x 508 x 508 x 508 x 584584

508 x 508 x 508 x 508 x 600600

Operating Operating systemsystem

MS-DOSMS-DOS WINDOWS WINDOWS NTNT

WINDOWS WINDOWS NTNT

WINDOWS WINDOWS NTNT

Weight kg Weight kg 461461 11001100 13631363 14551455

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BUILD STYLESBUILD STYLES

ACESACES

STARWEAVESTARWEAVE

QUICKCASTQUICKCAST

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ACESACES

Line Width

Hatch Spacing

Y

Z

X

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STARWEAVESTARWEAVE

Part Border

Hatch Spacing

X

Y

X

Y

Offset distance is half the hatch spacing

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QUICKCASTQUICKCAST

Vertex of one section is the centroid of the above previous section

Part Border

First Section

Second Section

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ADVANTAGESADVANTAGES

Unattended building process - The system is very stable. Unattended building process - The system is very stable. Once started the process is fully automatic and can be Once started the process is fully automatic and can be unattended until the process is completed. unattended until the process is completed.

Good dimensional accuracy - The process is able to Good dimensional accuracy - The process is able to maintain the dimensional accuracy of the built parts to maintain the dimensional accuracy of the built parts to within +/-0.1mm. within +/-0.1mm.

Good surface finish - Glass-like finishing can be obtained on Good surface finish - Glass-like finishing can be obtained on the top surfaces of the part although stairs can be found on the top surfaces of the part although stairs can be found on the side walls and curve surfaces between build layers. the side walls and curve surfaces between build layers.

The process is of high resolution and capable to build parts The process is of high resolution and capable to build parts with rather complex details with rather complex details

3D Systems Inc. have developed a software called "Quick 3D Systems Inc. have developed a software called "Quick cast" for building parts with hollow interior which can be cast" for building parts with hollow interior which can be used directly as wax pattern for investment casting used directly as wax pattern for investment casting

It is the most widely used process in the RP field It is the most widely used process in the RP field

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DISADVANTAGESDISADVANTAGES

Curling and warping - The resin absorb water as time goes Curling and warping - The resin absorb water as time goes by resulting curling and warping especially in the by resulting curling and warping especially in the relatively thin areas. relatively thin areas.

Relatively high cost (US$200-500K) - However, it is Relatively high cost (US$200-500K) - However, it is anticipated that the cost will be coming down shortly. anticipated that the cost will be coming down shortly.

Narrow range of materials - The material available is only Narrow range of materials - The material available is only photo sensitive resin of which the physical property, in photo sensitive resin of which the physical property, in most of the cases, cannot be used for durability and most of the cases, cannot be used for durability and thermal testing. thermal testing.

Post curing - The parts in most cases have not been fully Post curing - The parts in most cases have not been fully cured by the laser inside the vat. A post curing process is cured by the laser inside the vat. A post curing process is normally required. normally required.

High running and maintenance cost - The cost of the resin High running and maintenance cost - The cost of the resin and the laser gun are very expensive. Furthermore, the and the laser gun are very expensive. Furthermore, the optical sensor requires periodical fine tuning in order to optical sensor requires periodical fine tuning in order to maintain its optimal operating condition which will be maintain its optimal operating condition which will be considerable expensive. considerable expensive.

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APPLICATIONSAPPLICATIONS

Prototypes for concept models Prototypes for concept models Form-fit for assembly tests and Form-fit for assembly tests and

process planning process planning Models for investment casting, Models for investment casting,

replacement of the wax pattern replacement of the wax pattern Patterns for metal spraying, epoxy Patterns for metal spraying, epoxy

moulding and other soft tooling moulding and other soft tooling

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Stereolithography Models Aid Stereolithography Models Aid Surgeons with Ear ImplantsSurgeons with Ear Implants

For the prosthetic ear implant, prosthesis's began with a three-dimensional computed tomography scan. Data was used to create virtual models of the soft head tissue, the healthy ear and the bone structure at the implant site

•Three-dimensional software was used to create a mirror image of the patient's existing ear.•The ear was then virtually positioned in the correct place.•Cylinders, representing the implants, were positioned on the virtual ear, and soft tissue was virtually removed to reveal the points at which the implants would intersect with bone.•After checking bone quality, a virtual block was created to overlap the head and implants.•The skull and implant cylinders were subtracted from the block to create the template design, which was produced.•After sterilisation, the template was placed on the patient's head to indicate to the surgeon where to drill.

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