Mask Projection Micro StereolithographyHessel Maalderink

Precisiebeurs, woensdag 30 November 2011

Stereolithography

Courtesy CustomPartNet

Micro Stereo Lithography

Voxel size

Scal

e

Laser (2 photon)

Laser

Mask projection

nm μm mmCourtesy Laser Zentrum Hannover

Micro Stereo Lithography

Applications:PrototypingMasterRapid Manufacturing

Fields of operation:Medical DevicesElectronics / TelecomSensorsMicro fluidic systemsMechanical componentsMould makingJewelry

Courtesy RapidShape

DLP machine principle Spindle

Load cell

Platform

Reservoir

Mirror

Steppermotor

Projector

Shutter

Micro Stereo Lithography

3D Cad file STL file BitmapsTo project

Work flow

μSLA part

Introduction to micro stereolithography

Glass

Light curable resinCured Resin

Z-stage

DLP Projector

Micro stereolithography

Glass

Light curable resinCured Resin

Z-stage

DLP Projector

Micro stereolithography

Glass

Light curable resinCured Resin

Z-stage

DLP Projector

Micro stereolithography

Glass

Light curable resinCured Resin

Z-stage

DLP Projector

Micro stereolithography

Glass

Light curable resinCured Resin

Z-stage

DLP Projector

Micro stereolithography

Glass

Light curable resinCured Resin

Z-stage

DLP Projector

Force feedback mechanism

Micro Stereo Lithography

The Lepus® System

Closed LoopForce feedback

Layertime reduced to 3 seconds

Projecion: DLP, blueMotion Control: Force Feedback loopResolution: 1920 x 1080 pixelsPixel size 50 – 80 μmLayer thickness: 25 – 100 μmBuild envelope: 96x54x120 mm .. 154x87x120 mmBuild speed: 50 μm : up to 45 mm per hour

100 μm : up to 90 mm per hour

Process prototyping

Process prototypingProjecion: DLP, UVMotion Control: Force Feedback loopResolution: 1024 x 768 pixelsPixel size 4 μmLayer thickness: 5 – 25 μmBuild envelope: 40x30mm (4x3 mm)Stepping: Yes

µ SLADevelopment of custom additive manufacturing

systems, in a B2B consortium with industrial partners

Dental

Hearing aid

Jewelry

Courtesy RapidShape

Hessel Maalderink Confidential

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Geometric part quality influences

Pressure build-up

Support

LayersOptimizations: pixel size, layer thickness, design

1. LMT inherent limitations

2. Equipment quality

3. Material behavior

Hessel Maalderink Confidential

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Geometric part quality influences

Optimizations: equipment design, optical corrections

Z stagealignmentZ accuracyXY accuracy

Light engineAlignmentStabilityPicture quality

1. LMT inherent limitations

2. Equipment quality

3. Material behavior

GeometricSize & Aspect ratioTrapezoid & Cushion

Non geometricFocusLense flare, reflectionsIntensity variations (local)

Hessel Maalderink Confidential

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Geometric part quality influences

Optimizations: filled matrerials, smart illumination

1. LMT inherent limitations

2. Equipment quality

3. Material behavior

Through-cure (Z-bonus)Shrinkage

Curing shrinkageThermal shrinkage

Results in: - XY error- interlayer tension =>curl

Hessel Maalderink Confidential

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Smart correctionsOptical correction in slicerBoundary offset

Smart iIllumination strategyGrey pixels

Boundary improvementTension reduction (difference in contour and inner illumination)

Hessel Maalderink Confidential

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Geometric part quality influences

Geometric part quality is influenced by many factors.Special test geometries are needed to isolate them.

Benchmark Part

Angle’sHoles,Small featuresAccuracyInternal channelsZ-bonus…

Micro Stereo Lithography

Benchmark Part

Small features

Micro stereolithography - examples

Hearing aids

Courtesy of Widex

Layer thickness: 0.01 mm

© TNO © TNO

Total Height: 2,7 mm

Micro stereolithography - examples

• Digital Light Processing – Research.• Stepping to build larger parts with High Resolution.

© TNO © TNO

Micro stereolithography - examples

Micro fluidic structure

Courtesy D-Mec

Micro stereolithography - examples

Ongoing research: Processing highly filled material

Viscosity modification through dispersing agents

1,0E+02

1,0E+03

1,0E+04

1,0E+05

1,0E+06

1 10 100

Shear rate (1/s)

Visc

osity

(mPa

.s)

75wt% no disp

74 wt %

80 wt %

87 wt %

89 wt %

90 wt %

Optical characteristicsLight scattering due to ceramic particles influences spatial resolution of the uSLA process

Important parametersParticle size distributionRefractive index of ceramic particleRefractive index of photopolymerAbsorption coefficient of ceramic particle

First results

Al2O3 SiC

High Filled µSLADevelopment of additive manufacturing systems for high

filled materials, with partners in industry and research.

Next Step

Magnetic

Metals

Piëzo

Biomaterial

Ceramics

Organic

ZrO2

AlN

Al2O3

Ceramics

SiO2

SiC

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Micro Stereo Lithography

Questions