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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