3D printing

For methods of applying a 2-D image on a 3-D surface, see Pad printing. For methods of printing 2-D parallax stereograms that seem 3-D to the eye, see lenticular printing and holography.

Timelapse video of a hyperboloid object print (made of PLA) using a RepRap “Prusa Mendel” 3D printer for molten polymer deposition.

Part of a series on the
History of printing
Woodblock printing (200)
Movable type (1040)
Printing press (1454)
Etching (ca. 1500)
Mezzotint (1642)
Aquatint (1768)
Lithography (1796)
Chromolithography (1837)
Rotary press (1843)
Offset printing (1875)
Hectograph (19th century)
Hot metal typesetting (1886)
Mimeograph (1890)
Screen printing (1907)
Spirit duplicator (1923)
Dye-sublimation (1957)
Phototypesetting (1960s)
Dot matrix printer (1964)
Laser printing (1969)
Thermal printing (ca. 1972)
Inkjet printing (1976)
Stereolithography (1986)
Digital press (1993)
3D printing (ca. 2003)

3D printing is a phrase used to describe the process of creating three dimensional objects from digital file using a materials printer, in a manner similar to printing images on paper. The term is most closely associated with additive manufacturing technology, where an object is created by laying down successive layers of material. Recently the term is increasingly being used to describe all types of additive manufacturing processes, or even other types of rapid prototyping technology.

Since 2003 there has been large growth in the sale of 3D printers. Additionally, the cost of 3D printers has gone down. The technology also finds use in the fields of jewelry, footwear, industrial design, architecture, engineering and construction (AEC), automotive, aerospace, dental and medical industries, education, geographic information systems, civil engineering, and many others.

Methods

A number of competing technologies are available to do 3D printing. Their main differences are found in the way layers are built to create parts. Some methods use melting or softening material to produce the layers, e.g. selective laser sintering (SLS) and fused deposition modeling (FDM), while others lay liquid materials that are cured with different technologies, i.e. stereolithography (SLA). In the case of laminated object manufacturing (LOM), thin layers are cut to shape and joined together (i.e. paper, polymer, metal). Each method has its advantages and drawbacks, and consequently some companies offer a choice between powder and polymer as the material from which the object emerges. Generally, the main considerations are speed, cost of the printed prototype, cost of the 3D printer, choice and cost of materials and colour capabilities.

Molten polymer deposition

Fused deposition modeling (FDM), a technology developed by Stratasys that is used in traditional rapid prototyping, uses a nozzle to deposit molten polymer (i.e. ABS, PC, PC/ABS, PPSU) onto a support structure, layer by layer. FDM parts can be strengthened by wicking a metal into the part.

Granular materials binding

Another approach is selective fusing of print media in a granular bed. In this variation, the unfused media serves to support overhangs and thin walls in the part being produced, reducing the need for auxiliary temporary supports for the workpiece. Typically a laser is used to sinter the media and form the solid. Examples of this are selective laser sintering (SLS), using metals as well as polymers (i.e. PA, PA-GF, Rigid GF, PEEK, PS, Alumide, Carbonmide, elastomers), and direct metal laser sintering (DMLS).

Electron beam melting (EBM) is a similar type of additive manufacturing technology for metal parts (i.e. titanium alloys). EBM manufactures parts by melting metal powder layer by layer with an electron beam in a high vacuum. Unlike metal sintering techniques that operate below melting point, the parts are fully dense, void-free, and very strong.

The CandyFab printing system uses heated air and granulated sugar. It can be used to produce food-grade art objects.

Another method consists of an inkjet printing system. The printer creates the model one layer at a time by spreading a layer of powder (plaster, or resins) and inkjet printing a binder in the cross-section of the part. The process is repeated until every layer is printed. This technology is the only one^{[citation needed]} that allows for the printing of full colour prototypes. This method also allows overhangs, as well as elastomer parts. Unlike stereolithography, inkjet 3D printing is optimized for speed, low cost, and ease-of-use, making it suitable for visualizing during the conceptual stages of engineering design through to early-stage functional testing. No toxic chemicals like those used in stereolithography are required, and minimal post printing finish work is needed; one need only to use the printer itself to blow off surrounding powder after the printing process. Bonded powder prints can be further strengthened by wax or thermoset polymer impregnation.

Photopolymerization

The main technology in which photopolymerization is used to produce a solid part from a liquid is stereolithography (SLA).

In digital light processing (DLP), a vat of liquid polymer is exposed to light from a DLP projector under safelight conditions. The exposed liquid polymer hardens. The build plate then moves down in small increments and the liquid polymer is again exposed to light. The process repeats until the model is built. The liquid polymer is then drained from the vat, leaving the solid model. The ZBuilder Ultra is an example of a DLP rapid prototyping system.

The Objet PolyJet system uses an inkjet printer to spray photopolymer materials in ultra-thin layers (16 micron) layer by layer onto a build tray until the part is completed. Each photopolymer layer is cured by UV light immediately after it is jetted, producing fully cured models that can be handled and used immediately, without post-curing. The gel-like support material, which is designed to support complicated geometries, is removed by hand and water jetting. Also suitable for elastomers.

Ultra-small features may be made by the 3D microfabrication technique of multiphoton photopolymerization. In this approach, the desired 3D object is traced out in a block of gel by a focused laser. The gel is cured to a solid only in the places where the laser was focused, because of the nonlinear nature of photoexcitation, and then the remaining gel is washed away. Feature sizes of under 100 nm are easily produced, as well as complex structures such as moving and interlocked parts.

Yet another approach uses a synthetic resin that is solidified using LEDs.

Resolution

Resolution is given in layer thickness and X-Y resolution in dpi. Typical layer thickness is around 100 micrometres (0.1 mm), although some machines such as the Objet Connex series can print layers as thin as 16 micrometres. X-Y resolution is comparable to that of laser printers. The particles (3D dots) are around 50 to 100 micrometres (0.05-0.1 mm) in diameter.

Applications

“	Three-dimensional printing makes it as cheap to create single items as it is to produce thousands and thus undermines economies of scale. It may have as profound an impact on the world as the coming of the factory did....Just as nobody could have predicted the impact of the steam engine in 1750—or the printing press in 1450, or the transistor in 1950—it is impossible to foresee the long-term impact of 3D printing. But the technology is coming, and it is likely to disrupt every field it touches.	”
—The Economist, in a February 10, 2011 leader

A model (left) was digitally acquired by using a 3D scanner, the scanned data processed using MeshLab, and the resulting 3D model used by a rapid prototyping machine to create a resin replica (right)

An example of 3D printed limited edition jewellery. This necklace is made of glassfiber-filled dyed nylon. It has rotating linkages that were produced in the same manufacturing step as the other parts. Photography: Atelier Ted Noten.

Standard applications include design visualization, prototyping/CAD, metal casting, architecture, education, geospatial, healthcare and entertainment/retail. Other applications would include reconstructing fossils in paleontology, replicating ancient and priceless artifacts in archaeology, reconstructing bones and body parts in forensic pathology and reconstructing heavily damaged evidence acquired from crime scene investigations.

More recently, the use of 3D printing technology for artistic expression has been suggested. Artists have been using 3D printers in various ways. During the 2011 London Design Festival, an installation, curated by Murray Moss and focused on 3D Printing, took place in the Victoria and Albert Museum (the V&A). The installation was called Industrial Revolution 2.0: How the Material World will Newly Materialise.

3D printing technology is currently being studied by biotechnology firms and academia for possible use in tissue engineering applications where organs and body parts are built using inkjet techniques. Layers of living cells are deposited onto a gel medium and slowly built up to form three dimensional structures. Several terms have been used to refer to this field of research: organ printing, bio-printing, and computer-aided tissue engineering, among others. 3D printing can produce a personalized hip replacement in one pass, with the ball permanently inside the socket, and even at current printing resolutions the unit will not require polishing.

The use of 3D scanning technologies allow the replication of real objects without the use of molding techniques, that in many cases can be more expensive, more difficult, or too invasive to be performed; particularly with precious or delicate cultural heritage artifacts where the direct contact of the molding substances could harm the surface of the original object.

Industrial use

Industrial 3D printers have existed since the early 1980s, and have been used extensively for rapid prototyping and research purposes. These are generally larger machines that use proprietary plastics or cartridges, and are used for many rapid prototyping uses by universities and commercial companies. Industrial 3D printers are made by companies such as Ex One, Objet Geometries, Stratasys, 3D Systems, EOS GmbH, and Z Corporation.

Domestic use

RepRap version 2.0 (Mendel)

MakerBot Cupcake CNC

There are several projects and companies making efforts to develop 3D printers suitable for desktop use at a price many households can afford, many of which are related. Much of this work was driven by and targeted to DIY/enthusiast/early adopter communities, with links to both the academic and hacker communities.

The RepRap is a one of the longest running project in the Desktop category. The RepRap project aims to produce a FOSS 3D printer, whose full specifications are released under the GNU General Public License, and which can print many of its own parts (the printed parts) to create more machines. As of November 2010, the RepRap can print plastic parts, and requires motors, electronics, and some metal support rods to be completed.^{[citation needed]} Research is under way to enable the device to print circuit boards, as well as metal parts. Several companies and individuals sell parts to build various RepRap designs, the average price of a RepRap printer kit being €400 (US$537).^{[citation needed]}

Because of the FOSS aims of RepRap, many related projects have used their design for inspiration, creating an ecosystem of many related or derivative 3D printers, most of which are also Open Source designs. The availability of these open source designs means that variants of 3D printers are easy to invent. Unfortunately the quality and complexity of various printer designs, as well as quality of kit or finished products varies greatly from project to project. These printers include the MakerBot Industries Thing-O-Matic, Ultimaker, Shapercube, Mosaic, Prusa and Huxley 3D printers. This rapid development of open source 3-D printers is gaining interest in both the developed as well as the developing world as it enables both hyper-customization and the use of designs in the public domain to fabricate open source appropriate technology, which can assist in sustainable development as such technologies are easily and economically made from readily available resources by local communities to meet their needs.

Many of these printers are available in Kit form, and some are available as completed products. Prices of printer kits vary from US$350 for the open source SeeMeCNC H-1, US$500 for the Printrbot, both derived from previous RepRap models, to US$1800.^{[citation needed]}

Limits of 3D printing

Because 3D printers, like traditional manufacturing techniques, work with and use the base elements from the Periodic table of the elements, they are limited to them. If a gold ring or Silicon Transistors are desired, it would still require the printer to use actual Silicon or Gold.

Vendors and services

Some companies offer an on-line 3D printing service open both to consumers and to industry. People upload their own 3D designs to a 3D printing service company website, designs are printed via industrial 3D printers and then shipped to the customer.

3D printing service companies:

• Alphacam Teilefabrik, Schorndorf, Germany (custom 3D scanning and 3D printing)
• CNC Speedform AG, Werther, Germany and Losser, Netherlands (FDM, SLS: 6 machines, SLA: 2 machines, 3D printing: 1 Objet)
• eMachineShop, Mahwah, New Jersey, US (custom 3D parts, i.e. fused ABS plastic deposits)
• Fabidoo, Leipzig, Germany
• FigurePrints LLC, Redmond, Washington, US (HQ) with Vancouver, Canada production plant (specializes in figurines, i.e. World of Warcraft characters and Xbox Live avatars)
• Freedom Of Creation (FOC), Amsterdam, Netherlands (custom 3D design and printing)
• i.Materialise (custom 3D printing, also in titanium) / .MGX (custom 3D design), Leuven, Belgium (HQ) and New York City office
• JuJups (custom 3D printing) / Genometri (custom 3D design), Singapore
• Kraftwurx, Houston, Texas, US (custom 3D printing)
• Mi Adidas (personalized sports products on-demand)
• Ponoko, San Francisco, California, US (custom 3D printing and laser cutting)
• Sculpteo, Vanves, France (custom 3D printing)
• Shapeways, New York, New York, US (custom 3D printing)
• Zabfab Ltd, Manchester, UK (custom 3D printing)

See also

• Additive Manufacturing File Format
• List of common 3D test models
• List of emerging technologies
• Self-replicating machine

Further reading

• Easton, Thomas A. (November 2008). "The 3D Trainwreck: How 3D Printing Will Shake Up Manufacturing". Analog 128 (11): 50–63. 
• Wright, Paul K. (2001). 21st Century manufacturing. New Jersey: Prentice-Hall Inc.

External links

• 3-D printing at MIT
• New Dimension 3D Printing Machines
• 3D Printing, The Next Napster?
• New York Times: 3-D Printing Spurs a Manufacturing Revolution
• Times Online article - Microtrends: 3D Printing
• 3D printer reshapes world of copying
• 3D Printing for the Masses
• 'Gadget printer' promises industrial revolution New Scientist
• A Factory on Your Desk
• 3D Printing: The Printed World from The Economist
• What is 3D printing? A beginners guide to the desktop factory
• EADS Airbike made of steel-strength nylon
• Comparison chart of 3D printers
• Summary of the most popular 3D-Printer Manufactures