Additive Manufacturing Traditional fabrication Additive manufacturing – What? – Why? – How? Issues Design guidelines Examples The future? Additive ManufacturingIISME ETP L. Demsetz Summer 20141

Traditional fabrication IISME ETP L. Demsetz Summer 2014Additive Manufacturing2 Remove material (subtractive manufacturing) Image Sources: upper left lower left center upper right lower right

Traditional fabrication IISME ETP L. Demsetz Summer 2014 Additive Manufacturing3 Form in a mold (but must make the mold; some shapes won’t work) Image source: Lieu, Dennis K, and Sheryl Sorby. Visualization, Modeling, and Graphics for Engineering Design. Clifton Park, NY. Delmar Cengage Learning, 2009.

What is additive manufacturing? IISME ETP L. Demsetz Summer 2014Additive Manufacturing4 Image sources: icing: chocolate: rook: diffuser ring: Adding material layer by layer to create a part.

Why is this interesting? Additive manufacturing allows Low incremental cost to make a new part or modify an existing part Complicated part geometry; lighter parts Rapid fabrication (compared with subtractive processes) Little or no wasted material “In house” production IISME ETP L. Demsetz Summer 2014Additive Manufacturing5 Image sources: left: center: rignt:

How to go from idea to part? IISME ETP L. Demsetz Summer 2014Additive Manufacturing6 Idea Create a 3D model in software (SolidWorks, Creo, SketchUp) “Slice” and generate machine instructions for each layer (MakerWare or similar) Printer applies one layer at a time What angles can I print? Save in.stl format

Fused Deposition Modeling (FDM) Printing material (filament) is heated Molten material is extruded through a nozzle, solidifies on material below Nozzle moves in horizontal plane Build platform moves down after each layer is deposited Each layer is supported by the layer below Works with materials that can be melted at relatively low temperatures – acrylonitrile butadiene styrene (ABS) – polylactic acid (PLA) – other polymers, some metals IISME ETP L. Demsetz Summer 2014Additive Manufacturing7 Image sources: top: Esfandyar Kouhi, Syed Masood, Yos Morsi, (2008) "Design and fabrication of reconstructive mandibular models using fused deposition modeling", Assembly Automation, Vol. 28 Iss: 3, pp.246 – 254. bottom:

Sterolithography (SLA) IISME ETP L. Demsetz Summer 2014Additive Manufacturing8 Uses liquid resins that cure to a solid when exposed to light Build platform is contained in vat of resin Laser used to harden resin just above platform Platform moves vertically Laser used to harden next layer Usually requires post-processing (cleaning, removal of support structures Image sources: top: bottom left: bottom right:

Selective Laser Sintering (SLS) IISME ETP L. Demsetz Summer 2014Additive Manufacturing9 Layer of powder is spread on build platform Laser beam is used selectively sinter (fuse) into a solid. Build platform is lowered and another layer of powder is applied Unfused material supports fused structure Powder can be metal, ceramic, or polymer Image sources: top: bottom left and right:

Electron Beam Melting (EBM) IISME ETP L. Demsetz Summer 2014Additive Manufacturing10 Similar to SLS, but metal powder particles are fully melted (rather than just sintered at edges) Layer of metal power is spread on build platform Electron beam melts powder to form part layer Build platform is lowered and another layer of powder is applied Produces dense, strong parts Image sources: left: right: Greenemeier, Larry. “To Print the Impossible.” Scientific American 308, (2013) Published online: 16 April 2013.

Issues Time consuming to make many copies of the same part (compared with casting) Overhangs and small features may be difficult to make, especially with FDM Dimensional accuracy may be a problem, especially with FDM The properties of the resulting part depend on the material used, but may also depend on the details of the process (part orientation, layer thickness, print pattern, build speed) IISME ETP L. Demsetz Summer 2014Additive Manufacturing11 Not a big deal for some applications, but important to understand in others. Image sources: left: right:

Project printing guidelines IISME ETP L. Demsetz Summer 2014Additive Manufacturing12 FDM capabilities depend on the specific 3D printer and the material used. Here are some general guidelines for successful printing. To help secure the part to the platform use a “raft” or “tabs”. Consider sacrificial supports. Use more infill where stiffness is important Use more shells to improve surface finish & increase stiffness. Image sources: blue bird: Printing accuracy varies with machine. Test the capabilities of your printer!

More FDM printing guidelines IISME ETP L. Demsetz Summer 2014Additive Manufacturing13 Allow for filament width. The center of the nozzle follows the edge in your software model; the filament is wider. Unsupported overhangs that are less 20° above horizontal may cause problems. Orient the part to avoid unsupported features. Print complex curves in a horizontal (XY) plane to avoids “stair-step” effect caused by layers. Print intricate features on the top of the part to avoid damage when the part is removed.

Future directions Larger build envelopes? IISME ETP L. Demsetz Summer 2014Additive Manufacturing14 Filament with varying mechanical or thermal properties? Image sources: left and center: Lockheed Martin video Speaking of the Future: Advanced Manufacturing, right: BWH, video, 3D Printing at BWH, 3D printing of cells and tissue?

A few questions… IISME ETP L. Demsetz Summer 2014Additive Manufacturing15

IISME ETP L. Demsetz Summer 2014Additive Manufacturing16 A proposed “balloon-powered” car is shown below. The car is approximately 15 cm long. An inflated balloon is attached to the top; thrust is created as the air exits through a nozzle. The body of the car is a single piece. The wheels, axles, and axle locking pins are separate pieces. Discuss the advantages or disadvantages of making a prototype using FDM instead traditional manufacturing processes.

IISME ETP L. Demsetz Summer 2014Additive Manufacturing17 You have been asked to make these parts using FDM on a low cost 3D printer. How would you orient each part on the build platform? Are there any features that would be difficult to print? How would you set up the print process to avoid problems? ABCD Image source (A, C, D): Bertolini, Gary, et al. Fundamentals of Graphics Communication, 6 th Edition. New York: McGraw-Hill Higher Education, 2011.

References Additive Manufacturing Bertolini, Gary, et al. Fundamentals of Graphics Communication, 6th Edition. New York: McGraw-Hill Higher Education, Print. Gonzalez, Cecile J. The engineering behind additive manufacturing and the 3-D printing revolution. National Science Foundation. Web. 31 July Lieu, Dennis K, and Sheryl Sorby. Visualization, Modeling, and Graphics for Engineering Design. Clifton Park, NY : Delmar Cengage Learning, Print. 3D Printing. Wikipedia. Web. 31 July IISME ETP L. Demsetz Summer