Mechanical Properties of pLS Parts
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Questions and Answers

What was the first commercialized PBF process developed at the University of Texas at Austin, USA?

  • Binder jetting
  • Direct metal laser sintering (DMLS)
  • Selective laser sintering (SLS) (correct)
  • Electron beam melting (EBM)

    • What are the most common thermal sources for PBF processes?

  • Lasers (correct)
  • Electric arcs
  • Chemical reactions
  • Microwaves

    • What were LS processes originally developed to produce?

  • Composite materials
  • Metal components
  • Ceramic molds
  • Plastic prototypes (correct)

    • What do all PBF processes share in terms of characteristics?

    <p>One or more thermal sources for inducing fusion between powder particles</p> Signup and view all the answers

    What is one negative effect of loose powder sintering?

    <p>Agglomeration of powder particles increases average particle size</p> Signup and view all the answers

    What positive effect does loose powder sintering have on the powder bed?

    <p>Increases tensile and compressive strength</p> Signup and view all the answers

    What causes a region of the powder bed to become much hotter than the surrounding loose powder during part formation?

    <p>Thermally induced fusing of the desired cross-sectional geometry</p> Signup and view all the answers

    What is the primary function of the counter-rotating powder leveling roller in Powder Bed Fusion processes?

    <p>To fuse thin layers of powder</p> Signup and view all the answers

    Why is an enclosed chamber filled with nitrogen gas used in Powder Bed Fusion processes?

    <p>To minimize oxidation and degradation of the powdered material</p> Signup and view all the answers

    What thermal source is directed onto the powder bed to thermally fuse the material in Powder Bed Fusion processes?

    <p>Focused CO2 laser beam</p> Signup and view all the answers

    Why is a cool-down period required after completing each layer in Powder Bed Fusion processes?

    <p>To allow the parts to come to a low enough temperature that they can be handled and exposed to the ambient atmosphere</p> Signup and view all the answers

    Which type of materials are well-suited for powder bed processing due to their low melting temperatures, low thermal conductivities, and low tendency for balling?

    <p>Thermoplastic materials</p> Signup and view all the answers

    Which type of materials are suitable for making sacrificial patterns for investment casting using pLS?

    <p>Polystyrene-based materials with low residual ash content</p> Signup and view all the answers

    What aids in melting out the investment casting pattern after creating the ceramic shell?

    <p>Porosity</p> Signup and view all the answers

    Which type of polymers are resistant to degradation at elevated temperatures and chemicals like gasoline and automotive coolants?

    <p>Elastomeric thermoplastic polymers with rubber-like characteristics</p> Signup and view all the answers

    Which commercially available polymers for 3D printing are flame-retardant?

    <p>Polyamide and polyaryletherketone (PAEK or PEEK)</p> Signup and view all the answers

    Which composite materials have been investigated for bone replacement tissue scaffolds?

    <p>PCL and ceramic particles</p> Signup and view all the answers

    What type of fillers can polymers in PBF have to enhance their mechanical properties?

    <p>Glass bead filled polyamide materials</p> Signup and view all the answers

    Which metals can be processed using PBF?

    <p>Stainless steels, titanium, nickel-base alloys, aluminum alloys, cobalt-chrome</p> Signup and view all the answers

    What was RapidSteel developed by DTM Corp composed of?

    <p>Thermoplastic binder coated 1080 carbon steel powder with copper as the infiltrant</p> Signup and view all the answers

    What did LaserForm ST-100 allow for due to its broader particle size range?

    <p>Lower temperature sintering and infiltration in a single furnace run</p> Signup and view all the answers

    What proprietary powders did EOS market for direct tooling applications and parts requiring high thermal and electrical conductivities?

    <p>Nickel-based powders and Cu-based powders</p> Signup and view all the answers

    Which alloys are widely available for PBF production?

    <p>Titanium alloys, steel alloys, nickel-based super alloys, and CoCrMo</p> Signup and view all the answers

    What are the fusion mechanisms present in PBF processes?

    <p>Solid-state sintering, chemically induced binding, liquid-phase sintering, and full melting</p> Signup and view all the answers

    What did Phenix Systems develop commercial machines for?

    <p>Ceramics</p> Signup and view all the answers

    What is the primary fusion mechanism in most AM processes?

    <p>Sintering</p> Signup and view all the answers

    Which materials have been processed using PBF for medical applications?

    <p>Biocompatible materials like calcium hydroxyapatite</p> Signup and view all the answers

    What did advancements in mLS and EBM processes lead to?

    <p>The development of new alloys tailored for PBF production</p> Signup and view all the answers

    What are ceramics composed of?

    <p>Metal oxides, carbides, and nitrides</p> Signup and view all the answers

    Why are some alloys obsolete in favor of engineering-grade alloys?

    <p>Due to advancements in mLS and EBM technology</p> Signup and view all the answers

    What happens to crystal structures and mechanical properties in mLS?

    <p>They differ due to high solidification rates</p> Signup and view all the answers

    Study Notes

    Powder Bed Fusion Processes Overview

    • mLS and EBM technology have made some alloys obsolete in favor of engineering-grade alloys.
    • Titanium alloys, steel alloys, nickel-based super alloys, and CoCrMo are widely available for PBF production.
    • Alloys that crack under high solidification rates are not suitable for mLS.
    • Crystal structures and mechanical properties differ in mLS due to high solidification rates.
    • Advancements in mLS and EBM processes will lead to the development of new alloys tailored for PBF production.
    • Ceramics consist of metal oxides, carbides, and nitrides, and are available commercially.
    • Phenix Systems in France, acquired by 3D Systems, developed commercial machines for ceramics.
    • Ceramics and metal-ceramic composites have been demonstrated in research.
    • Biocompatible materials like calcium hydroxyapatite have been processed using PBF for medical applications.
    • Four fusion mechanisms are present in PBF processes: solid-state sintering, chemically induced binding, liquid-phase sintering, and full melting.
    • Solid-state sintering occurs at elevated temperatures without melting, driven by the minimization of total free energy of powder particles.
    • Sintering is important in most thermal powder processes, but few AM processes use sintering as a primary fusion mechanism.

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    Powder Bed Fusion Processes PDF

    Description

    Test your knowledge about the mechanical properties and applications of pLS parts produced using polyamide powders and polystyrene-based materials. Explore the unique microstructures and characteristics of these materials.

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