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Additive_Manufacturing_Macro-and-Micro.pdf
- 1. Modern Manufacturing Methods: Additive Manufacturing Rahul Panat School of Mechanical and Materials Engineering Washington State University 1
- 2. Outline • What is additive manufacturing? – Types of equipment/processes – Applications • Microscale Additive Printing – Processes at microscale – Applications Newmancraneins.com
- 3. What is additive manufacturing? • Subtractive Manufacturing – Any process of removing material – Milling, Cutting, Drilling, etc… • Additive Manufacturing – Any process of adding material – Filament, Laminate, Liquid, Powder, etc… • Rapid Prototyping – Original name • Additive Manufacturing – Best name • 3D Printing – Most common name
- 4. Types 4 Filament (FDM, FFF) Stratasys, RepRap, Makerbot†, 3D Systems Powder (Sintered – SLS or Electron beam) Eos, Arcam Powder (Inkjet Binder) Z-Corp‡, ExOne Liquid (SLA, DLP) 3D Systems Liquid (Inkjet) Objet†, Solidscape† Laminated Solido, Mcor †Owned by Stratasys ‡Owned by 3D Systems
- 6. RepRap vs Stratasys ~$550 RepRap Prusa ~$15000 uPrint Stratasys Sept 2011 A 0.254 mm layer is the smallest Stratasys can go.
- 7. Reprap vs SLA 3D Systems SLA-7000 @ 0.1mm vs RepRap Mendel Prusa @ 0.15 mm (RepRapBCN version) http://reprapbcn.wordpress.com/2012/05/24/reprap-mendel-prusa-vs-3dsystems-sla-7000-stereolithography/ ~$900 RepRap Prusa ~$650,000 3D Systems SLA-7000
- 8. Subtractive Processes • Series of material removal by machining and finishing operations • Typical Steps – Computer-based drafting packages, which can produce three- dimensional representations of parts – Interpretation software, which can translate the CAD file into a format usable by manufacturing software – Manufacturing software, which is capable of planning the operations required to produce the desired part shape – Computer-numerical-control (CNC) machinery, with capabilities necessary to produce the parts • Usually a soft material (usually a polymer or wax) is used as the work-piece
- 9. Additive Processes • Parts are built layer by layer – Stereolithography – Multi Jet/polyJet modeling – Fused-deposition modeling – Ballistic-particle manufacturing – Three-dimensional printing – Selective laser sintering – Electron-beam melting – Laminated object manufacturing • Differences in the method of producing individual slices – Typically 0.1–0.5 mm (0.004–0.020 in.) • Operations require dedicated software • Much faster than subtractive processes – – Few minutes to a few hours
- 10. Fused Deposition Modeling (FDM) • Gantry-robot controlled extruder head moves in two principal directions over a table, which can be raised and lowered as required • Extruder head is heated, and extrudes polymer filament at a constant rate through a small orifice. – Head follows a predetermined path – Extruded polymer bonds to the previously deposited layer • Drawbacks – Complex parts may be difficult to build directly because once the part has been constructed up to height a, the next slice would require the filament to be placed at a location where no material exists underneath to support it – Needs support material separately extruded https://www.youtube.com/watch?v=WHO6G67GJbM
- 11. Stereolithography • Curing (hardening) of a liquid photopolymer into a specific shape – Photocurable liquid-acrylate polymer – The liquid is a mixture of acrylic monomers, oligomers (polymer intermediates), and a photoinitiator (a compound that undergoes a reaction upon absorbing light) • The platform is lowered sufficiently to cover the cured polymer with another layer of liquid polymer, and the sequence is repeated • Part is removed from the platform, blotted, and cleaned ultrasonically and with an alcohol bath • Total cycle times in stereolithography range from a few hours to a day, without post-processing steps such as sanding and painting • Depending on their capacity, the cost of the machines is in the range from $100,000 to $400,000! https://www.youtube.com/watch?v=NM55ct5KwiI
- 12. Multijet/Polyjet Modeling • Print heads deposit the photopolymer on the build tray; UVt bulbs, alongside the jets, instantly cure and harden each layer • No need for post-modeling curing • Smooth surface of layers as thin as 16 μm • Two different materials are used: one for the actual model, and a second gel-like resin for support – Each material simultaneously jetted and cured, layer by layer – Support material removed later removed, with an aqueous solution https://www.youtube.com/watch?v=Som3CddHfZE Undoprototipos.com
- 13. Additive vs Subtractive Additive Subtractive
- 14. Selective Laser Sintering (SLS) • Sintering of non-metallic or, less commonly, metallic powders selectively into an individual object • Materials: Polymers (such as ABS, PVC, nylon, polyester, polystyrene, and epoxy), wax, metals, and ceramics, with appropriate binders • With ceramics and metals: common practice to sinter only a polymer binder that has been blended with the ceramic or metal powders – ceramic/metal sintered in a furnace Wikipedia https://www.youtube.com/watch?v=srg6fRtc-oc
- 15. Electron Beam Melting • E-beam, melting uses the energy source associated with an electron • beam to melt titanium or cobalt-chrome powder to make metal prototypes. The • workpiece is produced in a vacuum Fraunhofer. gov https://www.youtube.com/watch?v=jSH2vrtVNqQ Hindawi.com
- 16. Laminated Object Manufacturing • Roll-to-roll process is applied with heat activated glue or vinyl cutters https://www.youtube.com/watch?v=4ebj6hH0HnY
- 17. Three Dimensional Printing • A print head deposits an inorganic binder material onto a layer of polymer, ceramic, or metallic powder • Allows considerable flexibility in the materials and binders used • A piston, supporting the powder bed, is lowered incrementally, and with each step, a layer is deposited and then fused by the binder
- 18. Laser Engineered Net-Shaping • Metal powder sprayed on a part • Lasers used to sinter the powder LENSTM system creates near net shape manufacturing Turbine blade made by LENS at Sandia National Lab LENSTM: Laser enabled net-shaping (courtesy Optomec Inc) https://www.youtube.com/watch?v=SYbw1oSzPVA
- 19. Additive Manufacturing at Microscale
- 20. At Micro-scale: Additive vs Subtractive Subtractive Process Substrate 1 Clean substrate Cu Substrate 2 Conductive layer Cu Substrate Photoresist 3 Photoresist deposition Cu Substrate Photoresist UV light 4 UV Exposer Cu Substrate Photoresist 5 Photoresist development Cu Pattern Substrate 6 Etching Direct Write Process Substrate Substrate 2 3 Substrate 1 Clean substrate Printing Sintering Energy (Thermal, Laser, Photonic) Chemicals Mask
- 21. Advantages of Additive Processes vs Lithography • Additive methods typically have the below features –Minimal to no harmful chemicals –Fewer Steps –No material waste –Largely independence from the chemical compatibility of the substrate –Ability to manufacture on curved/vertical surfaces – Require large numbers of print-heads working on several units to realize large numbers of units/panel to lower cost
- 22. Micro-additive Methods Nanoscale ‘Pen’ DPN* Dip Pen Nanolithography (Science, Vol 283, Jan 1999). Microscale Pen (Advanced Materials 25: 4539-4543) Electric potential driven plating (J. Appl. Phys. 115, 044915 (2014)) Electric Field Driven Additive Method Microscale ‘Pen’ Movie Micro-Battery AFM tip for manufacturing
- 23. Methods: Inkjet Printing 3-D Antenna: Adv Materials, March 18 2011 Printed board: http://dx.doi.org/10.1145/2493432.2493486 Printed Electronics Printed Antenna Length scale >~50micron Drop on demand printing Low standoff height of ~2mm
- 24. Methods: Inkjet Printing • Most commonly used method is drop-on demand by – Thermal actuation (e.g. Hewlett-Packard) – Piezo actuation by pressure pulse using PZT (e.g. Epson) – Certain methods may include syringe pressure for larger diameter nozzle • Ink formulations are the key elements – Viscosity < 10cP – May include various elements like water, glycol – Could be UV curable – Non-Newtonian behavior (e.g. shear thinning) of the ink can influence the printing quality • Fluid Mechanics models can predict the printing volume per drop, velocity, etc as a function of puse voltage, fluid properties, and nozzle size Applied Mathematical Modelling, Volume 12, Issue 2, April 1988, Pages 182
- 25. Aerosol Jet • Clog resistance nozzle (sheath gas) • High density micro droplets • Continuous stream • Tightly focused (forced) • Able to print high viscosity ink (< 1000 cP) • Up to 500nm particles with line resolution 10µm Methods: Aerosol Jet Printing Ack: M. J Renn https://www.youtube.com/watch?v=F6_5L-Vtb0M • Aerosol particles created by ultrasonic energy or pneumatic pressure • Particles carried by a gas to deposit on a substrate
- 26. Methods: Aerosol Jet Printing • Mist of ink spheres 1-5µm in diameter, with several nanoparticles per drop • Equipment works to focus & collimate to reduce overspray • Aerosol particles are directed by stream of gas to ‘print’ on the substrate with forces acting on the particle • Forces on Aerosol Particle: – FSt + FBa + FVm + FPs + FGr + FMa + Fsa = FSt is Stokes force (steady viscous drag force) Fba is Basset force (nonsteady viscous drag force), FVm is the virtual mass force (inertia of fluid surrounding particle added to particle), FPs is the pressure gradient force, FGr is the buoyancy force caused by gravity, FMa is the Magnus lift force due to particle rotation, and FSa is the Saffman lift force on a particle with local shear flow ω is the vorticity of the fluid surrounding the particle and Ω is the angular rate of rotation of the particle * Journal of Nanotechnology, Vol 2012, Article ID 324380
- 27. Methods: Aerosol Jet Printing • Stokes and Saffman force are the most important forces in determining printing quality • Particle size, solvent viscosity etc determining factors for micro-additive printing quality • Overspray an issue, esp with on-equipment laser 100µm Tip ~10µm Beam Printing quality by Aerosol Jet Journal of Nanotechnology, Vol 2012, Article ID 324380
- 28. Nanoparticle Sintering • Sintering of nanoparticles determines porosity of micro-additive methods • Kinetics of sintering controlled by – Evaporation and condensation (EC) – Surface diffusion (SD) – Grain boundary diffusion (GDB) – Volume diffusion from the surface of the particle (VDS), – Volume diffusion from the interior of the particle (VDV) – Viscous flow (VF). Sintered nanoparticles
- 29. • Nanoparticles can sinter at much lower temperature compared to bulk counterparts due to their high s-t-v ratio – e.g. 100nm silver particles can sinter at 200 C, whereas bulk Ag MP is 961 C • Photonic energy can be used to selectively heat nanoparticles for short durations of time to avoid heating substrates • MP depression given by Nanoparticle Sintering Where: TMB=bulk melting temperature σsl=solid liquid interface energy Hf=bulk heat of fusion ρs=density of solid d=particle diameter 𝑇𝑇𝑀𝑀 𝑑𝑑 = 𝑇𝑇𝑀𝑀𝑀𝑀 1 − 4 𝜎𝜎𝑠𝑠𝑠𝑠 𝐻𝐻𝑓𝑓𝜌𝜌𝑠𝑠𝑑𝑑 Thermochimica Acta 463 (2007) 32–40 Gold Nanoparticle Data Phys Rev A, Vol. 13 (6) 1976
- 30. • Thermal sintering in an oven • Laser sintering • Photonic sintering by a flash of UV light • Plasma sintering Sintering Methods Photonic Curing Sinteron S2000 On-equipment laser for Aerosol Jet Highly porous structure Highly dense structure
- 31. Residual Stresses • Recent studies using neutron diffraction show significant residual strain/stresses in additively manufactured parts • Residual stresses can have adverse effect for structural and other applications • Residual stress for micro-additive manufacturing remains relatively unexplored Metallurgical and Materials Transactions A, 2014, Volume 45, Issue 13, pp 6260-6270
- 32. Reliability • Reliability requirements for micro-additively manufactured parts are same as that made using lithography/MEMS • Typical issues include – Degradation under thermal cycling – Degradation under cyclic mechanical load – Electro-migration under moisture/temperature conditions – Kirkendall voids under electrical current with dissimilar materials • Methods to assess reliability for printed electronics for newer applications yet to be standardized in industry http://reliabilitycalendar.org/blog/event/dfr-wearable-electronics-reliability-issues- and-real-life-solutions-in-printed-electronics/
- 33. Applications: 3-D Antennas • Metal dielectric structures for 3-D antennas Polymer Pillar (75 µm diameter) Metal Line (25µm wide) 400 µm Benefits: Electronic fabrication in 3-D that is difficult/impossible to make by lithography or MEMS Avoids the use of chemicals and results in minimal waste Electronics directly integrated with chips Journal of Micromechanics and Micro-engineering, Vol. 25 (10), 107002 (2015) Antenna-like structures fabricated at WSU Directional antenna simulation view Substrate Solid dielectric pillar micro- manufactured by dispense and cure
- 34. Applications: 3-D Dielectrics and Structural Materials • Metal dielectric structures as antennas Benefits: High strength to volume ratio structure possible Avoids the use of chemicals and results in minimal waste Electronics on vertical walls possible Si post (Ack. Dr. M. Renn) Micro Springs (Ack. Dr. M. Renn) Polymer cones fabricated at WSU
- 35. Applications: Transistors and Bio Parts Thin –film Transistors Biological Surface Mount Technology Association Pan Pacific Symposium, 2002 Nature Biotechnology 32, 773–785 (2014) • Several applications of direct printing of materials • The field has only been explored superficially