developed at Sandia National Laboratory, New Mexico, USA developed at Sandia National Laboratory New Mexico USA and commercialised by Optomec, USA presented by P S h IIT Kharagpur P Saha IIT Kh
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Motivation behind development p Fully dense functional metallic components. “Pick‐and‐ p place” material composition p to tailor
localized material characteristics within a part. Repair and overhaul technologies to extend the life of components in aging aircraft ship vehicles and weapon components in aging aircraft, ship, vehicles, and weapon systems. Convetional repair techniques such as MIG or TIG welding induce
excessive heat and a large HEAT AFFECTED ZONE (HAZ) destroying usefulness of the part. High cost of scrapping or maintaining critical parts, especially, when drawings do not exist, Parts deemed non‐repairable during their repair process
Fabricate spare part “as and when required” from its
original CAD design rather than keeping a huge inventory original CAD design, rather than keeping a huge inventory.
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Schematic of the LENS process Schematic of the LENS process
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LENS Process steps p A component is fabricated by creating a molten pool
through focusing a laser beam onto a substrate. Metal powder particles are simultaneously injected into the pool to add material. Using computer control the substrate is moved beneath Using computer control, the substrate is moved beneath the laser beam in the X‐Y plane, depositing a thin cross section of predetermined CAD generated geometry. Af d After deposition of a layer, the deposition head i i f l h d i i h d (consisting of a powder delivery nozzle and focusing lens assembly) is incremented in the positive Z‐direction, allowing generation of the next layer of the part. ll i i f h l f h Deposition of layers is repeated until the desired three‐ dimensional component has been layer additively formed.
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Powder delivery nozzle
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Construction of thin‐walled structure with four nozzle Construction of thin walled structure with four nozzle powder delivery system 11/11/2013
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Nd‐YAG laser vs. CO2 laser Since it is undesirable
to vaporize mateial as it is deposited optical it is deposited, optical absorption of material is critical for effective utilization of laser energy. With the exception of
copper, all of the copper all of the elemental metals shown in the graph have significantly g y absorption at the Nd‐ YAG laser wavelength as compared to CO2 laser. laser Fiber laser at 1070 nm has similar absorption as that of Nd‐YAG laser 11/11/2013
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Capabilities of LENS process p p Ability to build fully dense shapes Closed loop control of process for accurate part fabrication Ability to tailored deposition Abilit t t il d d iti parameters to feature size for speed, accuracy, t t f t i f d
and property control Composite and functionally graded material deposition Three axis and four axis systems for complex part fabrication Three‐axis and four‐axis systems for complex part fabrication With this technology, materials that either can not be cast and thermo‐ mechanically processed, or that can not be consolidated successfully by powder metallurgy, can be formed. Wide variety of materials d f l that, at minimum, include: stainless steel alloys h l d l l ll (316, 304L, 309, 17‐4), maraging steel (M300), nickel‐based superalloys (Inco designations 625,600, 718, 690), tool steel alloys (H13), titanium alloy ( (6Al‐4V), and other specialty materials 4 ), p y High cooling rate (102 – 103 K/s)leads to finer microstructure Mechanical properties similar or better than traditional processing methods
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Varying Composition y g p Multiple powder delivery nozzles are capable of
varying local composition. varying local composition
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Different Build Styles with Varying Different Build Styles with Varying p Composition Depending on the design criterion of a part, material composition in LENS can be varied through composite material deposition ‐ the powder composition remains constant for distinct build p regions, and functionally graded material (FGM) deposition ‐ the powder composition is continuously changing FGM requires a heavier interaction between the powder feeder controller and the LENS™ motion controller. controller 11/11/2013
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(a) A composite consists of distinct regions of A and B (b) Composites may be constructed by first drawing all of region A and then (c) drawing all of region B, allowing powder feeders to be reconfigured between compositions. (d) FGMs require the powder to be continually varied throughout the build (d) FGMs require the powder to be continually varied throughout the build. (e) each deposition vector in an FGM build will have a unique powder feeder profile.
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Powder Feeder Characterization Powder Feeder Set Up (Feeder, Screw, Feed line length etc.) Powder is transported from a powder hopper to the gas stream A screw‐feed device uses an open‐threaded shaft to meter powder into an
argon carrier gas stream A single carrier gas line is divided into two distinct flows, passed through the feeders and then recombined into a single line. Mixing of the two powders g p occurs naturally in the re‐joined argon stream y j g 11/11/2013
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For composites, the chief criterion for successful
deposition is that the powder feeders provide the desired powder composition for a given period of time. The system can effectively pause long enough yp g g for powder p compositions to be altered and reach steady state. For FGMs, there is a significant time lag between asking for
a given composition and when that composition is actually i j injected into the molten pool becomes critical. Hence d i h l l b i i l H thorough characterization of powder feeder is needed.
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OPTOMEC s OPTOMEC’s LENS‐850 SYSTEM
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F Features 1100 W continuous d G ase Nd‐YAG laser Fiber optic beam delivery 18 18”x18”x42” build x18 x42 build envelop 4th and 5th axis: rotary and tilt stages Control argon atmosphere with oxygen sensor Filtering system for particulate control CCD vision CCD i i Glove box Power 220V 3 phase 100A 14
LENS 850 system specifications S8 0 ifi i
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Materials deposited using the LENS Materials deposited using the LENS Process
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Measured tensile values for LENS v. Measured tensile values for LENS v g / p forged/annealed specimens
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Applications of LENS pp Tooling applications for Injection Mold Tooling and Die
Casting g where LENS' can improve cycle times by 50% and p y y5 extend mold life. Conformal cooling channels are possible. Repair and Overhaul applications due to small Heat Affected Zone (HAZ) allowing for higher yield and superior part repairs Zone (HAZ), allowing for higher yield and superior part repairs. Functional" Prototyping and Small Lot Manufacturing made possible due to producing fully dense metal parts with outstanding mechanical properties (high strength & ductility), di h i l i (hi h h & d ili ) not found with Rapid Prototyping systems Material Research : improvement of properties in existing p p p g alloys and composites; development of new alloys and composites. LENS' ability to provide multiple material gradient deposition offers unique material research options. deposition offers unique material research options 11/11/2013
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Applications pp
Building Up of Turbine Blade by LENS 11/11/2013
Finished Turbine Blade P Saha
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Applications pp
Thin Walled Housing H13 Tooling Impeller
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Substrate Included in Part
Six Inch Tall Thin Walled Part
Housing 11/11/2013
Finished Housing P Saha
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Tooling Parts by LENS Process g y
Injection Mold Cavity
Injection Molding Core
Conformal Cooling Channel 11/11/2013
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Tooling Parts by LENS Process g y
Trimming Die 11/11/2013
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In such an injection mold, a hard tool steel h d l l may be selectively placed in regions where excessive h i wear would be an issue, yet the bulk of the mold could be made of a material with a better coefficient of thermal conduction.)
Injection molding dies (core and cavity, CAD image and Final j g ( y, g fabricated parts) with copper chiller block and three‐ dimensional conformal cooling channel. 11/11/2013
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Processes similar to LENS Process
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C Controlled Metal Build‐UP (CMB) ll d M l B ild UP (CMB) (Developed at Fraunhofer IPT, Aachen Germany) (Developed at Fraunhofer IPT, Aachen Germany)
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Di Direct Metal Deposition (DMD) M lD i i (DMD) (Developed at University of Michigan, USA) (Developed at University of Michigan, USA)
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Comparison of Direct Metal Comparison of Direct Metal Freeform Processes Process
Deposition Type
Accuracy Horizontal
Layer Thickness
Deposition Rate
Materials
SLS
L Laser sintering i i
Hi h High
N/A
N/A
Steel, S l copper, Solder
SDM
Droplet based and cladding
N/A, Machined finish
Variable
30g/min
Stainless steel, INVAR
Welding
Welding
0.2-0.5 mm
Up to 50 mm
N/A, High
Steels, Numerous
Droplet based freeform fabr
Droplet based
N/A
N/A
25-150 m dia. droplets
Bi-Sn
LENS
Cladding
0.02mm, Z: 0 4mm 0.4mm
0.13-0.38 mm
N/A, Low
SS, Ti alloys, Numerous
DLF
Cladding
0.075-0.125 mm
0.075-0.125 mm
1-2g/min
SS, P20, Numerous
DMD at Michigan
Cladding
N/A
0 254 mm 0.254
0 1 4 1 cm3/min 0.1-4.1
H13, Al H13 Al, Numerous
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