Additive Manufacturing Technology Overview
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Transcript of Additive Manufacturing Technology Overview
Additive Manufacturing Technology Overview
Mike Klecka
United Technologies Research CenterEast Hartford, CT
June 18, 2014
Presentation Overview
Additive Manufacturing Technology
Comparison of Additive Manufacturing Methods
Typical Post Processing Requirements
Multiple Material Designs
Additive Manufacturing with Cold Spray
Suitability of Parts for Additive Manufacturing
Design and Redesign for AM
AM Process Selection
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Increasing Pressure on Manufacturing
Requirements• Shorter time to market• Higher performance requirements• Increased product life, durability• Reduced weight• Lower cost• Higher yield and quality• Improved energy efficiency• Less waste, environmentally friendly
Potential benefits from additive manufacturing• Reduced machining time, energy, & cost• Reduced material consumption• Material solutions and combinations not
otherwise possible• Increased part complexity
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Additional challenges• Increasingly complex part
geometries and systems• Expanded material options• Manufacturability concerns• Slow adoption of new techniques• Qualification of new processes
Additive Manufacturing Overview• Additive manufacturing is broadly defined as the addition of functional material
to a substrate, after which is either incorporated into the substrate as the finished part or is separated from the substrate to yield a free standing part• Added ribs to a sheet or panel for stiffening• Added lugs to a tube for mounting• 3D printing of entire components on a build plate
• Majority of techniques utilize powder feedstock• Some use wire, sheet, or strip stock
Non-Powder Based Techniques• Laser wire feed, EB wire, ultrasonic, laminated object• Advantages – High deposit rates, low cost feedstock• Disadvantages – Poor part tolerance, required post
machining, moderate property potential
Powder Bed Techniques• Laser powder bed, DMLS, EBM• Advantages – Small features, tight
tolerance, fully inert environment • Disadvantages – Low deposition rate,
limited part size, single material
Powder Deposition Techniques• Cold spray, LENS, Laser applied powder• Advantages – Moderate part sizes, in situ
alloying, moderate deposition rates, dissimilar materials
• Disadvantages – Lower dimensional accuracy, less tolerance control
Build Core
Added Material
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DMLS, LPB, EBM, powder bed fusion Potential for widest variety of geometry Limited to one material Low deposition rates (0.05 - 0.5 kg/hour) Part size limited by dimensions of powder bed Advantages – Small features, tight tolerance, high
geometric fidelity, fully inert environment Disadvantages – Stress relief & heat treatment often
required, slow build rates, limited part size
Powder Bed
LENS, laser applied powder (LAP) Multiple build directions Multiple material deposition Moderate deposit rates (0.5 – 1 kg/hour) Advantages – Moderate geometric fidelity, shield
gas environment, cladding/repair/resurfacing Disadvantages – Moderate feature size, moderate
property potential, gravity concerns with build direction
Laser Powder Injection
Laser Applied Powder
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Comparison of Additive Manufacturing
http://en.wikipedia.org/wiki/Selective_laser_sintering
Comparison of Additive Manufacturing
High plastic work during deposition High deposition rates (3 – 15 kg/hour) Limited to line-of-sight processing Lower geometric fidelity Advantages – Solid state processing, good
mechanical properties, multi-material, bonding of dissimilar materials
Cold Spray
Laser/EB Wire Additive LAW, MIG, EB Wire High rates (3 – 10 kg/hour) Low cost feedstock Low feature tolerance Moderate property potential
Ultrasonic & Laminated Object UC, UAM, LOM High build rates Sheet, strip feedstock Limited geometry Solid state
Granular Material Bonding Powder bed inkjet & binder jetting 3D printing sand, casting molds/cores Plaster based printing (PP) Low material properties, low cost Sintered metal, polymer, & ceramics
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ASM Handbook, Vol.6A, Welding Fundamentals and Processes (2011)
Conductive ink printing, conformal surfaces Potential for wide variety of geometries Excellent resolution depending on technique Multiple material deposition Micro cold spray
Direct Write
Thermoplastic-based (neat or filled) Layer-by-layer deposition Extrusion & shrinkage limits high resolution Capable of complex geometries and low
density cores Multiple material deposition, limited properties
Fused Deposition
Actuators, Motors & MEMS
Sensors & Arrays
SLA, Large Area Maskless Photopolymerization (LAMP) Ceramics and polymers, UV curing materials Complex geometries with good resolution Restricted material selection, resin is often expensive
Stereolithography
Prototype parts
Cores
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Comparison of Additive Manufacturing
http://en.wikipedia.org/wiki/Stereolithography
http://en.wikipedia.org/wiki/Fused_deposition_modelling
Metal Based AM Comparison
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Dep
ositi
on R
ate
Feature Resolution
Laser Powder Bed
Electron Beam Powder Bed
Laser Applied Powder
Wire Feed Techniques
Cold Spray
Ultrasonic Fabrication
AM technology publicizes less raw material waste compared to conventional machining Cold Spray: Deposition efficiency and overspray can
vary significantly based on material Laser Applied Powder: Capture rates between 40%
and 80%, depending on process conditions Powder Bed: Un-sintered powder has potential to be
reclaimed and reused - gives rise to additional questions of repeatability and quality
Wire Feed: Captures better than 90%, similar with ultrasonic; often requires post machining
Common constraints for each AM technique Part Size: Powder beds limited in size, typically less
than 12 inches, while wire feed can accommodate 10 foot long sections or more
Build Speed: Powder beds often take many hours (often more than 24 for large structures), LAP may take up to 12 hours or more, wire feed less than 6 hours
Material Properties: Melting processes result in strength similar to cast, solid state processes (cold spray & ultrasonic) may be better
Often overlooked aspect of AM: Post processing requirements1. Stress relieving via heat treatment to prevent part distortion
• Due to rapid cooling rates, AM parts often contain large residual stresses• Conducted while part remains affixed to build plate
2. Removal of part from build plate, typically via EDM3. Heat treatment to reach required microstructure and mechanical properties
• As deposited, AM parts often resemble cast microstructures• Directionality is common, with grain structures oriented in the build direction• May require HIP to reduce porosity and improve density• Homogenization and solution treatment to reduce grain orientation• Hardening/precipitation/strengthening/quench/temper heat treatment, as required
4. Finish machining to meet required geometry and tolerances5. Peening, grit blasting, and tumbling to improve surface finish6. Inspection for defects/flaws
Example: Powder Bed
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Typical Post Processing Requirements
Part distortion in laser applied powder after removal from build plate
Multiple Material Designs Additive techniques offering multiple material solutions:
Injected powder laser additive (LAP, LENS, etc.) Cold spray deposition Ultrasonic consolidation
Multiple material part fabrication Weight reduction Light weight base/core material Hard, wear resistant surface Integrated component designs
Potential for advanced materials
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Cold spray tensile sample, deposited on steel mandrel with engineered release
layer
Potential for buildup of uniform section possible through proper gun manipulation
More complicated geometries possible
through mandrel concept
Level of Finish Machining Required• Mandrel design• Material used• Dimensional requirements• Accuracy of spray path
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Additive Manufacturing with Cold Spray
Support with sharp drop-off
CS deposit
Features for planar truss
Inner curvature
Outer curvature
Front faceSide truss
Rear leg: outward (convex) curvature
Front leg: inward
(concave) curvature
(a)
(b) (c)
(d) (e)
Support
Sprayed part
Component: Structural mount
Process: Cold spray additive manufacturing
Structural modeling & optimization indicate preferred geometry
Critical factors: Material properties and layout Process parameters Structural performance Geometric process
characteristics…
Case Study: Optimization of Additively Manufactured Structural Mount
Structural mount
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θ1
Substrate is flat
θ2
Substrate drops off
Trapezoidal cross section
Additive Manufacturing Process DependenceDifferent outcomes by process and properties
Design for the cold spray process using removable mandrel
Design for direct metal laser sintering (DMLS) powder bed process
Design conception for the laser applied powder (LAP)
process
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Suitability of Parts for Additive Manufacturing
1. Existing clear business case for using AM Many processing steps, intensive machining AM saves time, has less raw material waste
2. No existing business case, but redesign could create one Current design more expensive with AM Redesigned part could be more cost effective using
additive technique Consolidation of multi-part assembly into single
component
3. No existing business case, low likelihood that redesign could impact Low cost conventional processing (e.g., stamping) Satisfactory performance High part volumes required
AM makes sense for some, but not all components
Redesign may improve the performance independent
of cost
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Redesign for Additive Manufacturing
Conventional manufacturing Well-established limits in feature shape and complexity
Casting Forging Machining
Higher cost often associated with feature complexity and low weight
Additive manufacturing New areas of design space Often no penalty for more complexity Possible lower cost associated with higher feature
complexity and lower weight Redesign for AM requires creativity and new ways of thinking
Parts suited for additive manufacturing may look different than traditional counterparts
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Additive Manufacturing Technique Selection
Some key considerations Size of part Geometric tolerance Surface finish Throughput Geometric complexity Feature size Single- or multi-material Mechanical properties Microstructure …
AM technologies are rapidly evolving
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Dep
ositi
on R
ate
Feature Resolution
Laser Powder Bed
Electron Beam Powder Bed
Laser Applied Powder
Wire Feed Techniques
Cold Spray
Ultrasonic Fabrication
Thank You
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