Post on 04-Jun-2018
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8/13/2019 Laser Engineered Net Shaping
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LENS
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LASER ENGINEERED NET SHAPING
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ANOTHER RAPID PROTOTYPINGPROCESS!
Net-shape = Final shape
Uses metal powder
Powder is supplied coaxiallyalong with laser
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UNBEATABLE WHEN IT COMES TOREPAIR
Gear with broken tooth
Mass
Gear with tooth by LENS
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COMPONENTSSANDIA LABS-OPTOMEC
Nd:YAG laser with sixinch focal length planoconvex lens
Hermetically sealedglass enclosure ,backfilled with argon,operating at a nominaloxygen level of 2-3parts per million.
Base plate with 3-axiscomputer controlledpositioning system
Powderfeed unit
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PROCEDURE
High power laser melts site of deposition
Powder deposited by nozzle into hot-spot
Laser builds cross-section in raster-scan fashion
Table lowered by layer thickness
New layer constructed on top of previous layer
Repeat process till build is complete
Melt pool protected by inert gases
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APPLICATIONS
Metal components made of state-of-the-art materials such astitanium and Inconel
Medical implants
Material discovery-Aluminide composites, Tic
Hybrid manufacturing- product enhancement
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DIAGNOSTICS Laser Doppler velocimetry for powder flow and relative density of the
powder
Time resolved infrared imaging for thermal characteristics
High magnification, high speed digital imaging and standard videoimaging
Material build-up height, the melt depth into the previous layer
Component velocityLaser irradianceZ-axis increment (thickness of layer)Powder volumetric flow rate.
PROCESS VARIABLES
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POWDER SIZE
Particles do not become molten until they are actually injectedinto the melted metal puddle in the deposition region
For smaller particle sizes , the melt puddle appeared to be stableand well behaved.
For larger particle size distributions, the molten puddle was veryenergetic and unstable
Directing the larger particles into the molten deposition regioncauses a larger displacement of the liquid metal thus adding moreenergy to the oscillations of the melt pool
Surface finish of 12-25 micrometre
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MATERIAL PROPERTIES
Tests revealed properties to be as good or even better thancasted/wrought parts
Textured growth of the deposited material occurred across thedeposition layer boundary in nearly all cases for thin-walled parts
Little inter-granular melting in the substrate region The absence of equilibrium and metastable phases in the
microstructures suggest the very high cooling rates associatedwith LENS process
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SOME FACTS
Roughly eight feet long, eight feet highand 3.5 feet wide.
$350,000 to $500,000
Dimensions in the X-Y plane could bemaintained to less than 0.002
inches(0.02 mm).
The dimension in the Z or growthdirection could only be maintainedwithin 0.015 inches.