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

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

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 Build Core Added Material 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

Comparison of Additive Manufacturing Powder Bed 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 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

Comparison of Additive Manufacturing Cold Spray 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 Ultrasonic & Laminated Object LAW, MIG, EB Wire High rates (3 – 10 kg/hour) Low cost feedstock Low feature tolerance Moderate property potential 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 Powder bed inkjet & binder jetting 3D printing sand, casting molds/cores Plaster based printing (PP) Low material properties, low cost Sintered metal, polymer, & ceramics

Comparison of Additive Manufacturing Direct Write 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 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 Cores Prototype parts http://en.wikipedia.org/wiki/Fused_deposition_modelling Stereolithography 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

Metal Based AM Comparison 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 Deposition Rate Feature Resolution Laser Powder Bed Electron Beam Powder Bed Laser Applied Powder Wire Feed Techniques Cold Spray Ultrasonic Fabrication 8

Typical Post Processing Requirements Example: Powder Bed Often overlooked aspect of AM: Post processing requirements 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

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

Additive Manufacturing with Cold Spray Potential for buildup of uniform section possible through proper gun manipulation Support with sharp drop-off CS deposit 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

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… Trapezoidal cross section θ1 Substrate is flat θ2 Substrate drops off 12

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 13

Suitability of Parts for Additive Manufacturing AM makes sense for some, but not all components Existing clear business case for using AM Many processing steps, intensive machining AM saves time, has less raw material waste 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 No existing business case, low likelihood that redesign could impact Low cost conventional processing (e.g., stamping) Satisfactory performance High part volumes required Redesign may improve the performance independent of cost

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

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 Deposition Rate Feature Resolution Laser Powder Bed Electron Beam Powder Bed Laser Applied Powder Wire Feed Techniques Cold Spray Ultrasonic Fabrication

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