Additive Manufacturing Technology Overview
Mike Klecka
United Technologies Research Center
East 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
2
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
Additional challenges
• Increasingly complex part
geometries and systems
• Expanded material options
• Manufacturability concerns
• Slow adoption of new techniques
• Qualification of new processes
Potential benefits from additive manufacturing
• Reduced machining time, energy, & cost
• Reduced material consumption
• Material solutions and combinations not
otherwise possible
• Increased part complexity
3
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
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
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
Build
Core
Added Material
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Comparison of Additive Manufacturing
Powder Bed
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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
http://en.wikipedia.org/wiki/Selective_laser_sintering
Laser Powder Injection
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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 Applied Powder
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Comparison of Additive Manufacturing
Cold Spray
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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
Laser/EB Wire Additive
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LAW, MIG, EB Wire
High rates (3 – 10 kg/hour)
Low cost feedstock
Low feature tolerance
Moderate property potential
Ultrasonic & Laminated Object
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UC, UAM, LOM
High build rates
Sheet, strip feedstock
Limited geometry
Solid state
ASM Handbook, Vol.6A, Welding Fundamentals and Processes (2011)
Granular Material Bonding
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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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Comparison of Additive Manufacturing
Direct Write
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Conductive ink printing, conformal surfaces
Potential for wide variety of geometries
Excellent resolution depending on technique
Multiple material deposition
Micro cold spray
Actuators,
Motors &
MEMS
Sensors & Arrays
Fused Deposition
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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
Prototype
parts
Cores
http://en.wikipedia.org/wiki/Fused_deposition_modelling
Stereolithography
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SLA, Large Area Maskless Photopolymerization (LAMP)
Ceramics and polymers, UV curing materials
Complex geometries with good resolution
Restricted material selection, resin is often expensive
http://en.wikipedia.org/wiki/Stereolithography
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Metal Based AM Comparison
 AM technology publicizes less raw material waste
compared to conventional machining
 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
Deposition Rate
 Common constraints for each AM technique
Laser Powder Bed
Electron Beam Powder Bed
Laser Applied Powder
Ultrasonic Fabrication
Wire Feed Techniques
Feature Resolution
 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
Cold Spray
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Typical Post Processing Requirements
Example: Powder Bed
Often overlooked aspect of AM: Post processing requirements
1.
2.
3.
4.
5.
6.
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
Removal of part from build plate, typically via EDM
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
Finish machining to meet required geometry and tolerances
Peening, grit blasting, and tumbling to improve surface finish
Inspection for defects/flaws
Part distortion in laser applied powder after removal from build plate
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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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Additive Manufacturing with Cold Spray
Potential for buildup of uniform section
possible through proper gun manipulation
CS deposit
Support with sharp drop-off
Cold spray tensile sample, deposited
on steel mandrel with engineered
release layer
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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Case Study: Optimization of Additively Manufactured Structural Mount
 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…
Structural mount
(a)
Features for
planar truss
(b)
(c)
Outer curvature
Side truss
Front face
θ1
Substrate is flat
θ2
Substrate
drops off
Trapezoidal cross
section
Inner curvature
(d)
(e)
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Additive Manufacturing Process Dependence
Different 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
AM makes sense for some, but not all components
1.
Existing clear business case for using AM
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Many processing steps, intensive machining
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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
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Consolidation of multi-part assembly into single
component
3.
Redesign may
improve the
performance
independent
of cost
No existing business case, low likelihood that redesign
could impact

Low cost conventional processing (e.g., stamping)

Satisfactory performance

High part volumes required
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Redesign for Additive Manufacturing
Parts suited for additive manufacturing may look different than traditional counterparts
 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
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Additive Manufacturing Technique Selection
Deposition Rate
Laser Powder Bed
Electron Beam Powder Bed
Laser Applied Powder
Ultrasonic Fabrication
Wire Feed Techniques
Feature Resolution
 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
Cold Spray
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Thank You
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