8 3 D Printing Additive Manufacturing Fall 2013

8. 3 D Printing & Additive Manufacturing Fall 2013 Prof. Marc Madou MSTB 120

HISTORY 3 D printing has been in existence for almost three decades, yet has only recently spread to mass markets. The primary 3 DPrinting techniques were established in the eighties (Stereo. Lithography, fused deposition modeling, and laser sintering). These innovations were theoretically groundbreaking, but most practical applications remained prohibitively expensive.

How we got here Adrian Bowyer’s Rep. Rap project changed the game forever. The Rep. Rap project, established in 2004, aimed to make 3 d printers financially accessible to everyone. Rep. Rap printers had the ability to materialize CAD designs and also to print the essential parts necessary to assemble a clone printer. The movement incorporated open-source file sharing, thus allowing users to share their 3 D designs and ideas.

Evolution After the growth of the Rep. Rap movement, companies such as Bot. Mill, Maker. Bot, and Bits from Bytes began manufacturing consumer-friendly 3 D printers. Now 3 D printing has reached a new stage of development: small businesses, educational institutions and large corporations are pushing the bounds of the possible. Meanwhile, consumer adoption continues rushing forward, capturing a broader slice of the population with ever-decreasing prices.

Market Landscape 3 D printing is approximately a $600 million-dollar industry. The industry goliath, 3 D Systems Corporation, by itself reported a 2011 net income of $41 Million. The 3 D printing industry is comprised of different segments. The primary 3 DPrinting users include hobbyists, artists, educational institutions, engineering firms, and industrial manufacturers. These segments can be further broken down into three end-uses.

Segment 1 First, there are consumers (designers, inventors) who want their own 3 Ddesigns printed, but can’t afford or don’t need to own their own printer. They will seek out a 3 D-Printing service like Shapeways, Imaterialise, or Sculpteo to get their object printed. The consumer simply uploads his/her 3 D file, chooses the material and build size, and within weeks, the service will print and deliver their 3 d model.

Segment 2 The second category consists of hobbyists or diyers, seeking their own personal printers; these printers, provided by companies like Bot. Mill, Maker. Bot, and Bits. From. Bytes, range from $800 to $5000. Initially, most hobbyists were most interested in assembling and constructing the printer itself –less interested in the final product. Now, as more printers come preassemble (ready-to-print), greater attention is given to the 3 d models themselves.

Segment 3 Third, there is the high-end educational/industrial segment. Lastly, educational institutions, engineering firms, and other large corporations that want to possess their own heavy-duty printers can invest anywhere from $10, 000 to $80, 000 per printer.

Fused Deposition Modeling (FDM) 1. A spool of themoplastic wire (typically acrylonitrile butadiene styrene (ABS)) with a 0. 012 in (300 μm) diameter is continuously supplied to a nozzle 5. The sacrificial support material (if available) is dissolved in a heated sodium hydroxide (Na. OH) solution with the assistance of ultrasonic agitation. 2. The nozzle heats up the wire and extrudes a hot, viscos strand (like squeezing toothpaste of of a tube). 3. A computer controls the nozzle movement along the x- and y-axes, and each crosssection of the prototype is produced by melting the plastic wire that solidifies on cooling. 4. In the newest models, a second nozzle carries a support wax that can easily be removed afterward, allowing construction of more complex parts. The most common support material is marketed by Stratasys under the name Water. Works) 10

3 D Printing (3 DP) 1. A layer of powder (plaster, ceramic) is spread across the build area 2. Inkjet-like printing of binder over the top layer densifies and compacts the powder locally 3. The platform is lowered and the next layer of dry powder is spread on top of the previous layer 4. Upon extraction from the machine, the dry powder is brushed off and recycled

Selective Laser Sintering (SLS) 1. A continuous layer of powder is deposited on the fabrication platform 2. A focused laser beam is used to fuse/sinter powder particles in a small volume within the layer 3. The laser beam is scanned to define a 2 D slice of the object within the layer 4. The fabrication piston is lowered, the powder delivery piston is raised and a new layer is deposited 5. After removal from the machine, the unsintered dry powder is brushed off and recycled

EBM (Electron Beam Melting) This solid freeform fabrication method produces fully dense metal parts directly from metal powder with characteristics of the target material. The EBM machine reads data from a 3 D CAD model and lays down successive layers of powdered material. These layers are melted together utilizing a computer controlled electron beam. In this way it builds up the parts. The process takes place under vacuum, which makes it suited to manufacture parts in reactive materials with a high affinity for oxygen, e. g. titanium. The melted material is from a pure alloy in powder form of the final material to be fabricated (no filler). For that reason the electron beam technology doesn't require additional thermal treatment to obtain the full mechanical properties of the parts. That aspect allows classification of EBM with selective laser melting (SLM) where competing technologies like SLS and DMLS require thermal treatment after fabrication. Compared to SLM and DMLS, EBM has a generally superior build rate because of its higher energy density and scanning method. The EBM process operates at an elevated temperature, typically between 700 and 1 000 °C, producing parts that are virtually free from residual stress, and eliminating the need for heat treatment after the build.

Poly. Jet/Multijet Modeling (MJM) • Both systems use piezoelectric print heads with thousands of nozzles to jet 16 micron droplets of photopolymer that are immediately cured by UV light. The model material for the part and the support material that fills the voids come from different nozzles. • • • The Objet system uses a photopolymer as support material; the support material is designed to crosslink less than the model material and is washed away with pressurized water. The 3 D Systems In. Vision uses wax as support material, which can be melted away. Because of its 600 x 600 dpi resolution, MJM is a relatively fast process. The resolution is not as good as for SLA.

Stereo-lithography (SLA) • The liquid resin is kept either in the fixed surface mode or in the free surface mode. – In the case of free surface, solidification occurs at the resin/air interface, and care needs to be taken to avoid waves or a slant of the liquid surface. – In the fixed surface mode, the resin is stored in a container with a transparent window plate for exposure. The solidification happens at the stable window/resin interface. An elevator is pulled up over the thickness of one additional layer above the window for each new exposure.

Stereo-lithography (SLA) • The two major types of stereolithography and projection stereolithography. are scanning – The scanning stereolithography parts are constructed in a point-by-point and line-byline fashion, with the sliced shapes written directly from a computerized design of the cross-sectional shapes by a beam in the liquid. – Projection stereolithography is a parallel fabrication process that enables sets of truly 3 D solid structures made of a UV polymer by exposing the polymer with a set of 2 D cross-sectional shapes (masks) of the final structures. These 2 D shapes are either a set of real photomasks used to subsequently expose the work, or they involve a dynamic mask projection system instead of a physical mask.

Stereo-lithography (SLA) TWO-PHOTON LITHOGRAPHY Two-photon lithography provides a further enhancement of the SLA resolution. If an entangled photon pair comes out from a point of the object plane, it undergoes twophoton diffraction, resulting in a very narrow point spread function on the image plane. The result is extremely local polymerization, with resolutions in the tens of nanometers range.

Polylactic acid (PLA) PLA, or polylactic acid, is an ideal material to use in 3 D printers. It is pleasant to work with, available in optically clear forms, and produces no noxious fumes when extruded; the odor has been likened to candy floss and it is made from the natural acid present in yogurt. The Natural filament has no additives and is quite safe to use with foodstuffs – the material is used to make soluble sutures for surgery and it doesn’t affect the lactose intolerant. Mechanically, it fuses together well when molten and will shatter rather than bend. Its melting point is relatively low at 180 C and it softens in boiling water. When molten, the clear forms have very low viscosity and so extrude rapidly. Opaque colorants stiffen the plastic, lessening its tendency to shatter and preventing it from flowing away. It also has a very low resistance on steel bars and is used for printing sliding bearings. Generally extruded at between 180 C (320 F) and 190 C (340 F). Clear PLA is suitable as the core for investment castings, as the plastic vaporizes leaving little ash. It will not biodegrade unless properly composted.

Acrylonitrile butadiene styrene (ABS) Acrylonitrile butadiene styrene is a common plastic, used to make such things as Lego bricks and monitor cases. It is recyclable but does produce styrene fumes and other gasses when heated that some find unpleasant, and good ventilation is recommended. It is tougher than PLA and withstands 60 C with ease. It flexes rather than shatters, but abrades away when pressed on by axles etc. Extrusion is done at anywhere between 220 C and 270 C, and any blockages should be cleared with acetone while cool as ABS will turn to ash if you try to burn it out.

3 mm ABS Filament

3 mm PLA Filament

Stratasys ABS+ Plus Filament

Stratasys SST Filament

1. 75 mm ABS Raft Detail

Dimension ABS Build Detail

UP 1. 75 mm ABS Build Detail

Dimension SST Build Detail

UP Edge Build Detail

UP Edge Build Detail

Dimension SST Edge Detail. 020

2 Photon Lithography

2 Photon Lithography

2 Photon Lithography

2 Photon Lithography

2 Photon Lithography

2 Photon Lithography

Bio-Printing Drop on demand cell Printer

Bio-Printing Heart Valve Printer

Bio-Printing Cartilage Tissue Printer

Bio-Printing Captive Shell Cell Tissue Printer

Bio-Printing Muscle Tissue Printer

Bio-Printing Cell Scaffold Printer

Bio-Printing Cartilage Tissue Printer

Bio-Printing 3 D Printed Ear with Electronics

Bio-Printing 3 D Printed Droplet Network of Cells

Bio-Printing 3 D Printed Hearing Aid Shell 10, 000 3 D printed hearing aids in circulation worldwide

Candy. Fab 4000 Sugar drop on demand 3 D Printer

Large Format 3 D Concrete Printer

Large Format 3 D Concrete Printer

Large Format 3 D Concrete Printer Tennessee Ball Clay

Large Format 3 D Concrete Printer

Large Format FDM

Micro-Stereo. Lithography

Micro-Stereo. Lithography

Micro-Stereo. Lithography

Free form 3 D Printer

Free form 3 D Printer

Cell Printer

Prototype Delta 3 D Printer

3 D Food Printer

Food Printer Burritob 0 t

3 D Solar Powered Sand Printer

Ceramic Printing Orbital Re-entry 3 D printed alumina/silica architected sandwich panel after bisque firing and sintering. (a) Isometric view; (b) Front view. The external vertical columns were printed to support the face sheet during sintering and preserve the shape of the part. They were removed prior to infiltration and testing

Ceramic Printing Orbital Re-entry (a) Sintered ceramic cylinder embedded in epoxy resin. Notice that the resin partially wicks through the cylinder (coloring was added to emphasize the gradient in composition). (b) Optical micrograph of a crosssection of the cylinder in (a), showing a gradient in resin volume fraction; (c) Digital thresholding of the image in (b), clearly showing a gradient in porosity. Notice that the infiltrated (hybrid) regions are nearly fully dense, whereas ~50% porosity remains in the ceramic regions.

Material Properties as they exist now Randal Schubert, HRL Laboratories @ 2013

A Vision for Additive Manufacturing Model Manufacturing Platforms (MMP) 72

Open Source & Creative Commons Pwdr (3 D Powder Printer) http: //pwdr. github. io/ 3 D Bioprinter http: //blog. makezine. com/2013/04/19/howto-diy-bioprinter/ 3 D Laser Sintering http: //blog. makezine. com/2012/02/01/anopen-source-laser-sintering-3 d-printer/

Thank You ! Ed Tackett, Director etackett@uci. edu www. rapidtech. org Facebook ~ Rapid. Tech