3D printing

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History of printing
Woodblock printing 200 Movable type 1040 Printing press c. 1440 Etching c. 1515 Mezzotint 1642 Aquatint 1772 Lithography 1796 Chromolithography 1837 Rotary press 1843 Hectograph 1869 Offset printing 1875 Hot metal typesetting 1884 Mimeograph 1886 Photostat and Rectigraph 1907 Screen printing 1910 Spirit duplicator 1923 Xerography 1938 Phototypesetting 1949 Inkjet printing 1951 Dye-sublimation 1957 Dot matrix printing 1968 Laser printing 1969 Thermal printing c. 1972 3D printing 1984 Digital printing 1993

3D printing, also known as additive manufacturing (AM), refers to various processes used to synthesize a three-dimensional object.^[1] In 3D printing, successive layers of material are formed under computer control to create an object.^[2] These objects can be of almost any shape or geometry and are produced from a 3D model or other electronic data source. A 3D printer is a type of industrial robot.

Futurologists such as Jeremy Rifkin ^[3] believe that 3D printing signals the beginning of a third industrial revolution,^[4] succeeding the production line assembly that dominated manufacturing starting in the late 19th century. Using the power of the Internet, it may eventually be possible to send a blueprint of any product to any place in the world to be replicated by a 3D printer with "elemental inks" capable of being combined into any material substance of any desired form.

3D printing in the term's original sense refers to processes that sequentially deposit material onto a powder bed with inkjet printer heads. More recently, the meaning of the term has expanded to encompass a wider variety of techniques such as extrusion and sintering-based processes. Technical standards generally use the term additive manufacturing for this broader sense.

History

Terminology and methods

Early Additive Manufacturing (or AM) equipment and materials were developed in the 1980s.^[5] In 1981, Hideo Kodama of Nagoya Municipal Industrial Research Institute invented two AM fabricating methods of a three-dimensional plastic model with photo-hardening polymer, where the UV exposure area is controlled by a mask pattern or the scanning fiber transmitter.^[6][7] But on July 16, 1984 Alain Le Méhauté, Olivier de Witte and Jean Claude André filed their patent for the stereolithography process.^[8] It was three weeks before Chuck Hull filed his own patent for stereolithography. The application of French inventors were abandoned by the French General Electric Company (now Alcatel-Alsthom) and CILAS (The Laser Consortium).^[9] The claimed reason was “for lack of business perspective”.^[10] Then in 1984, Chuck Hull of 3D Systems Corporation^[11] developed a prototype system based on a process known as stereolithography, in which layers are added by curing photopolymers with ultraviolet light lasers. Hull defined the process as a "system for generating three-dimensional objects by creating a cross-sectional pattern of the object to be formed,"^[12][13] but this had been already invented by Kodama. Hull's contribution is the design of the STL (STereoLithography) file format widely accepted by 3D printing software as well as the digital slicing and infill strategies common to many processes today. The term 3D printing originally referred to a process employing standard and custom inkjet print heads. The technology used by most 3D printers to date—especially hobbyist and consumer-oriented models—is fused deposition modeling, a special application of plastic extrusion.

AM processes for metal sintering or melting (such as selective laser sintering, direct metal laser sintering, and selective laser melting) usually went by their own individual names in the 1980s and 1990s. At the time, nearly all metal working was produced by casting, fabrication, stamping, and machining; although plenty of automation was applied to those technologies (such as by robot welding and CNC), the idea of a tool or head moving through a 3D work envelope transforming a mass of raw material into a desired shape layer by layer was associated by most people only with processes that removed metal (rather than adding it), such as CNC milling, CNC EDM, and many others. But AM-type sintering was beginning to challenge that assumption. By the mid 1990s, new techniques for material deposition were developed at Stanford and Carnegie Mellon University, including microcasting^[14] and sprayed materials.^[15] Sacrificial and support materials had also become more common, enabling new object geometries.^[16]

The umbrella term additive manufacturing gained wider currency in the decade of the 2000s.^[17] As the various additive processes matured, it became clear that soon metal removal would no longer be the only metalworking process done under that type of control (a tool or head moving through a 3D work envelope transforming a mass of raw material into a desired shape layer by layer). It was during this decade that the term subtractive manufacturing appeared as a retronym for the large family of machining processes with metal removal as their common theme. However, at the time, the term 3D printing still referred only to the polymer technologies in most minds, and the term AM was likelier to be used in metalworking contexts than among polymer/inkjet/stereolithography enthusiasts. The term subtractive has not replaced the term machining, instead complementing it when a term that covers any removal method is needed.

By the early 2010s, the terms 3D printing and additive manufacturing developed senses in which they were synonymous umbrella terms for all AM technologies. Although this was a departure from their earlier technically narrower senses, it reflects the simple fact that the technologies all share the common theme of sequential-layer material addition/joining throughout a 3D work envelope under automated control. (Other terms that have appeared, which are usually used as AM synonyms (although sometimes as hypernyms), have been desktop manufacturing, rapid manufacturing [as the logical production-level successor to rapid prototyping], and on-demand manufacturing [which echoes on-demand printing in the 2D sense of printing].) The 2010s were the first decade in which metal parts such as engine brackets^[18] and large nuts^[19] would be grown (either before or instead of machining) in job production rather than obligately being machined from bar stock or plate.

As technology matured, several authors had begun to speculate that 3D printing could aid in sustainable development in the developing world.^[20][21][22]

General principles

Modeling

3D printable models may be created with a computer aided design (CAD) package, via a 3D scanner or by a plain digital camera and photogrammetry software. 3D printed models created with CAD results in reduced errors and can be corrected before printing, allowing verification in the design of the object before it is printed.^[23]

The manual modeling process of preparing geometric data for 3D computer graphics is similar to plastic arts such as sculpting. 3D scanning is a process of collecting digital data on the shape and appearance of a real object, creating a digital model based on it.

Printing

Before printing a 3D model from an STL file, it must first be examined for errors. In fact, most of the CAD softwares produced errors in the STL files:^[24] holes, faces normals, self-intersections, noise shells or manifold errors.^[25] This step is called "repair", as the original model needs to be fixed.^[26][27] Generally STLs that have been produced from a model obtained through 3D scanning often have more of these errors.^[28] This is due to how 3D scanning works : as it's often point to point acquisition, reconstruction will include errors in most cases.^[29]

Once completed, the STL file needs to be processed by a piece of software called a "slicer," which converts the model into a series of thin layers and produces a G-code file containing instructions tailored to a specific type of 3D printer (FDM printers). This G-code file can then be printed with 3D printing client software (which loads the G-code, and uses it to instruct the 3D printer during the 3D printing process).

Printer resolution describes layer thickness and X-Y resolution in dots per inch (dpi) or micrometers (µm). Typical layer thickness is around 100 µm (250 DPI), although some machines can print layers as thin as 16 µm (1,600 DPI).^[30] X-Y resolution is comparable to that of laser printers. The particles (3D dots) are around 50 to 100 µm (510 to 250 DPI) in diameter.

Construction of a model with contemporary methods can take anywhere from several hours to several days, depending on the method used and the size and complexity of the model. Additive systems can typically reduce this time to a few hours, although it varies widely depending on the type of machine used and the size and number of models being produced simultaneously.

Traditional techniques like injection moulding can be less expensive for manufacturing polymer products in high quantities, but additive manufacturing can be faster, more flexible and less expensive when producing relatively small quantities of parts. 3D printers give designers and concept development teams the ability to produce parts and concept models using a desktop size printer.

Finishing

Though the printer-produced resolution is sufficient for many applications, printing a slightly oversized version of the desired object in standard resolution and then removing material^[31] with a higher-resolution subtractive process can achieve greater precision.

Some printable polymers such as ABS, allow the surface finish to be smoothed and improved using chemical vapor processes.^[32]

Some additive manufacturing techniques are capable of using multiple materials in the course of constructing parts. These techniques are able to print in multiple colors and color combinations simultaneously, and would not necessarily require painting.

Some printing techniques require internal supports to be built for overhanging features during construction. These supports must be mechanically removed or dissolved upon completion of the print.

All of the commercialized metal 3D printers involve cutting the metal component off the metal substrate after deposition. A new process for the GMAW 3D printing allows for substrate surface modifications to remove aluminum^[33] or steel.^[34]

Processes

Several 3D printing processes have been invented since the late 1970s. The printers were originally large, expensive, and highly limited in what they could produce.^[5]

A large number of additive processes are now available. The main differences between processes are in the way layers are deposited to create parts and in the materials that are used. Some methods melt or soften the material to produce the layers, for example. selective laser melting (SLM) or direct metal laser sintering (DMLS), selective laser sintering (SLS), fused deposition modeling (FDM),^[35] or fused filament fabrication (FFF), while others cure liquid materials using different sophisticated technologies, such as stereolithography (SLA). With laminated object manufacturing (LOM), thin layers are cut to shape and joined together (e.g., paper, polymer, metal). Each method has its own advantages and drawbacks, which is why some companies offer a choice of powder and polymer for the material used to build the object.^[36] Others sometimes use standard, off-the-shelf business paper as the build material to produce a durable prototype. The main considerations in choosing a machine are generally speed, costs of the 3D printer, of the printed prototype, choice and cost of the materials, and color capabilities.^[37]

Printers that work directly with metals are generally expensive. However less expensive printers can be used to make a mold, which is then used to make metal parts.^[38]

Type	Technologies	Materials
Extrusion	Fused deposition modeling (FDM) or Fused Filament Fabrication (FFF)	Thermoplastics, eutectic metals, edible materials, Rubbers, Modeling clay, Plasticine, Metal clay (including Precious Metal Clay)
	Robocasting or Direct Ink Writing (DIW)	Ceramic materials, Metal alloy, cermet, metal matrix composite, ceramic matrix composite
Light polymerized	Stereolithography (SLA)	Photopolymer
	Digital Light Processing (DLP)	Photopolymer
Powder Bed	Powder bed and inkjet head 3D printing (3DP)	Almost any metal alloy, powdered polymers, Plaster
	Electron-beam melting (EBM)	Almost any metal alloy including Titanium alloys
	Selective laser melting (SLM)	Titanium alloys, Cobalt Chrome alloys, Stainless Steel, Aluminium
	Selective heat sintering (SHS)[39]	Thermoplastic powder
	Selective laser sintering (SLS)	Thermoplastics, metal powders, ceramic powders
	Direct metal laser sintering (DMLS)	Almost any metal alloy
Laminated	Laminated object manufacturing (LOM)	Paper, metal foil, plastic film
Wire	Electron beam freeform fabrication (EBF3)	Almost any metal alloy

Extrusion deposition

Fused deposition modeling (FDM), derives from automatic polymeric foil hot air welding system, hot-melt glueing and automatic gasket deposition. Such principle has been further developed by S. Scott Crump in the late 1980s and was commercialized in 1990 by Stratasys.^[40] After the patent on this technology expired, a large open-source development community developed and both commercial and DIY variants utilizing this type of 3D printer appeared. As a result, the price of this technology has dropped by two orders of magnitude since its creation.

In fused deposition modeling the model or part is produced by extruding small beads of material which harden immediately to form layers. A thermoplastic filament or metal wire that is wound on a coil is unreeled to supply material to an extrusion nozzle head (3D printer extruder). The nozzle head heats the material and turns the flow on and off. Typically stepper motors or servo motors are employed to move the extrusion head and adjust the flow. The printer usually has 3 axes of motion. A computer-aided manufacturing (CAM) software package is used to generate the G-Code that is sent to a microcontroller which controls the motors.

Extrusion in 3D printing using material extrusion involves a cold end and a hot end.

Various polymers are used, including acrylonitrile butadiene styrene (ABS), polycarbonate (PC), polylactic acid (PLA), high density polyethylene (HDPE), PC/ABS, polyphenylsulfone (PPSU) and high impact polystyrene (HIPS). In general, the polymer is in the form of a filament fabricated from virgin resins. There are multiple projects in the open-sourced community aimed at processing post-consumer plastic waste into filament. These involve machines used to shred and extrude the plastic material into filament. Additionally, fluoropolymers such as PTFE tubing are used in the process due to the material's ability to withstand high temperatures. This ability is especially useful in transferring filaments.^[41]

FDM is somewhat restricted in the variation of shapes that may be fabricated. For example, FDM usually cannot produce stalactite-like structures, since they would be unsupported during the build. Otherwise, a thin support must be designed into the structure, which can be broken away during finishing. Fused deposition modeling is also referred to as fused filament fabrication (FFF) by companies who do not hold the original patents like Stratasys does.

Binding of granular materials

Another 3D printing approach is the selective fusing of materials in a granular bed. The technique fuses parts of the layer and then moves upward in the working area, adding another layer of granules and repeating the process until the piece has built up. This process uses the unfused media to support overhangs and thin walls in the part being produced, which reduces the need for temporary auxiliary supports for the piece. A laser is typically used to sinter the media into a solid. Examples include selective laser sintering (SLS), with both metals and polymers (e.g., PA, PA-GF, Rigid GF, PEEK, PS, Alumide, Carbonmide, elastomers), and direct metal laser sintering (DMLS).^[42]

Selective Laser Sintering (SLS) was developed and patented by Dr. Carl Deckard and Dr. Joseph Beaman at the University of Texas at Austin in the mid-1980s, under sponsorship of DARPA.^[43] A similar process was patented without being commercialized by R. F. Housholder in 1979.^[44]

Selective laser melting (SLM) does not use sintering for the fusion of powder granules but will completely melt the powder using a high-energy laser to create fully dense materials in a layer-wise method that has mechanical properties similar to those of conventional manufactured metals.

Electron beam melting (EBM) is a similar type of additive manufacturing technology for metal parts (e.g. 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, EBM parts are void-free.^[45][46]

Another method consists of an inkjet 3D printing system. The printer creates the model one layer at a time by spreading a layer of powder (plaster, or resins) and printing a binder in the cross-section of the part using an inkjet-like process. This is repeated until every layer has been printed. This technology allows the printing of full color prototypes, overhangs, and elastomer parts. The strength of bonded powder prints can be enhanced with wax or thermoset polymer impregnation.

Lamination

In some printers, paper can be used as the build material, resulting in a lower cost to print. During the 1990s some companies marketed printers that cut cross sections out of special adhesive coated paper using a carbon dioxide laser and then laminated them together.

In 2005 Mcor Technologies Ltd developed a different process using ordinary sheets of office paper, a tungsten carbide blade to cut the shape, and selective deposition of adhesive and pressure to bond the prototype.^[47]

There are also a number of companies selling printers that print laminated objects using thin plastic and metal sheets.

Photopolymerization

Stereolithography was patented in 1986 by Chuck Hull.^[48] Photopolymerization is primarily used in stereolithography (SLA) to produce a solid part from a liquid. This process was a dramatic departure from the "photosculpture" method of François Willème (1830–1905) developed in 1860 and the photopolymerization of Mitsubishi's Matsubara in 1974.^[49]

The "photosculpture" method consisted of photographing a subject from a variety of equidistant angles and projecting each photograph onto a screen, where a pantograph was used to trace the outline onto modeling clay.^[50][51][52] In photo-polymerization, a vat of liquid polymer is exposed to controlled lighting under safelight conditions. The exposed liquid polymer hardens. Polymerization occurs when photopolymers are exposed to light when photopolymers contain chromophores, otherwise, the addition of molecules that are photosensitive are utilized to react with the solution to begin polymerization. Polymerization of monomers lead to cross-linking, which creates a polymer. Through these covalent bonds, the property of the solution is changed.^[23] The build plate then moves down in small increments and the liquid polymer is again exposed to light. The process repeats until the model has been built. The liquid polymer is then drained from the vat, leaving the solid model. The EnvisionTEC Perfactory^[53] is an example of a DLP rapid prototyping system.

Inkjet printer systems like the Objet PolyJet system spray photopolymer materials onto a build tray in ultra-thin layers (between 16 and 30 µm) until the part is completed. Each photopolymer layer is cured with UV light 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. It is also suitable for elastomers.

Ultra-small features can be made with the 3D micro-fabrication technique used in multiphoton photopolymerisation. This approach uses a focused laser to trace the desired 3D object into a block of gel. Due to the nonlinear nature of photo excitation, the gel is cured to a solid only in the places where the laser was focused while the remaining gel is then washed away. Feature sizes of under 100 nm are easily produced, as well as complex structures with moving and interlocked parts.^[54]

Yet another approach uses a synthetic resin that is solidified using LEDs.^[55]

In Mask-image-projection-based stereolithography a 3D digital model is sliced by a set of horizontal planes. Each slice is converted into a two-dimensional mask image. The mask image is then projected onto a photocurable liquid resin surface and light is projected onto the resin to cure it in the shape of the layer.^[56] The technique has been used to create objects composed of multiple materials that cure at different rates.^[56] In research systems, the light is projected from below, allowing the resin to be quickly spread into uniform thin layers, reducing production time from hours to minutes.^[56] Commercially available devices such as Objet Connex apply the resin via small nozzles.^[56]

Metal wire processes

Laser-based wirefeed systems, such as Laser Metal Deposition-wire (LMD-w), feed wire through a nozzle that is melted by a laser using inert gas shielding in either an open environment (gas surrounding the laser), or in a sealed chamber. Electron beam freeform fabrication uses an electron beam heat source inside a vacuum chamber.

It is also possible to use conventional gas metal arc welding attached to a 3D stage to 3-D print metals such as steel and aluminum.^[57] Low-cost open source RepRap-style 3-D printers have been outfitted with Arduino-based sensors and demonstrated reasonable metallurgical properties from conventional welding wire as feedstock.^[58]

Printers

Industry use

As of October 2012, additive manufacturing systems were on the market that ranged from $2,000 to $500,000 in price and were employed in industries including aerospace, architecture, automotive, defense, and medical replacements, among many others. For example, General Electric uses the high-end model to build parts for turbines.^[59] Many of these systems are used for rapid prototyping, before mass production methods are employed.

Consumer use

Several projects and companies are making efforts to develop affordable 3D printers for home desktop use. Much of this work has been driven by and targeted at DIY/Maker/enthusiast/early adopter communities, with additional ties to the academic and hacker communities.^[60]

RepRap Project is one of the longest running projects in the desktop category. The RepRap project aims to produce a free and open source hardware (FOSH) 3D printer, whose full specifications are released under the GNU General Public License, and which is capable of replicating itself by printing many of its own (plastic) parts to create more machines.^[61][62] RepRaps have already been shown to be able to print circuit boards^[63] and metal parts.^[64][65]

Because of the FOSH aims of RepRap, many related projects have used their design for inspiration, creating an ecosystem of 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. The quality and complexity of printer designs, however, as well as the quality of kit or finished products, varies greatly from project to project. This rapid development of open source 3D printers is gaining interest in many spheres as it enables hyper-customization and the use of public domain designs to fabricate open source appropriate technology. This technology can also assist initiatives in sustainable development since technologies are easily and economically made from resources available to local communities.^[20][21]

The cost of 3D printers has decreased dramatically since about 2010, with machines that used to cost $20,000 now costing less than $1,000.^[66] For instance, as of 2013, several companies and individuals are selling parts to build various RepRap designs, with prices starting at about €400 / US$500.^[67] The open source Fab@Home project^[68] has developed printers for general use with anything that can be squirted through a nozzle, from chocolate to silicone sealant and chemical reactants. Printers following the project's designs have been available from suppliers in kits or in pre-assembled form since 2012 at prices in the US$2000 range.^[67] The Kickstarter funded Peachy Printer is designed to cost $100^[69] and several other new 3D printers are aimed at the small, inexpensive market including the mUVe3D and Lumifold. Rapide 3D has designed a professional grade crowdsourced 3D-printer costing $1499 which has no fumes nor constant rattle during use.^[70] The 3Doodler, "3D printing pen", raised $2.3 million on Kickstarter with the pens selling at $99,^[71] though the 3D Doodler has been criticized for being more of a crafting pen than a 3D printer.^[72]

As the costs of 3D printers have come down they are becoming more appealing financially to use for self-manufacturing of personal products.^[73] In addition, 3D printing products at home may reduce the environmental impacts of manufacturing by reducing material use and distribution impacts.^[74]

In addition, several RecycleBots such as the commercialized Filastruder have been designed and fabricated to convert waste plastic, such as shampoo containers and milk jugs, into inexpensive RepRap filament.^[75] There is some evidence that using this approach of distributed recycling is better for the environment.^[76]

The development and hyper-customization of the RepRap-based 3D printers has produced a new category of printers suitable for small business and consumer use. Manufacturers such as Solidoodle,^[59] Robo 3D, RepRapPro and Pirx 3D have introduced models and kits priced at less than $1,000, thousands less than they were in September 2012.^[59] Depending on the application, the print resolution and speed of manufacturing lies somewhere between a personal printer and an industrial printer. A list of printers with pricing and other information is maintained.^[67] Most recently delta robots, like the TripodMaker, have been utilized for 3D printing to increase fabrication speed further.^[77] For delta 3D printers, due to its geometry and differentiation movements, the accuracy of the print depends on the position of the printer head.^[78]

Some companies are also offering software for 3D printing, as a support for hardware manufactured by other companies.^[79]

Large 3D printers

Large 3D printers have been developed for industrial, education, and demonstrative uses. A large delta-style 3D printer was built in 2014 by SeeMeCNC. The printer is capable of making an object with diameter of up to 4 feet (1.2 m) and up to 10 feet (3.0 m) in height. It also uses plastic pellets as the raw material instead of the typical plastic filaments used in other 3D printers.^[80]

Another type of large printer is Big Area Additive Manufacturing (BAAM). The goal is to develop printers that can produce a large object in high speed. A BAAM machine of Cincinnati Incorporated can produce an object at the speeds 200-500 times faster than typical 3D printers available in 2014. Another BAAM machine is being developed by Lockheed Martin with an aim to print long objects of up to 100 feet (30 m) to be used in aerospace industries.^[81]

Microscale and nanoscale 3D printing

Microelectronic device fabrication methods can be employed to perform the 3D printing of nanoscale-size objects. Such printed objects are typically grown on a solid substrate, e.g. silicon wafer, to which they adhere after printing as they're too small and fragile to be manipulated post-construction.

In one technique, 3D nanostructures can be printed by physically moving a dynamic stencil mask during the material deposition process, somewhat analogous to the extrusion method of traditional 3D printers. Programmable-height nanostructures with resolutions as small as 10 nm have been produced in this fashion, by metallic physical vapor deposition through a piezo-actuator controlled stencil mask having a milled nanopore in a silicon nitride membrane.^[82]

Another method enhances the photopolymerization process on a much smaller scale, using finely-focused lasers controlled by adjustable mirrors. This method has produced objects with feature resolutions of 100 nm.^[83]

Manufacturing 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^[84]

AM technologies found applications starting in the 1980s in product development, data visualization, rapid prototyping, and specialized manufacturing. Their expansion into production (job production, mass production, and distributed manufacturing) has been under development in the decades since. Industrial production roles within the metalworking industries^[85] achieved significant scale for the first time in the early 2010s. Since the start of the 21st century there has been a large growth in the sales of AM machines, and their price has dropped substantially.^[86] According to Wohlers Associates, a consultancy, the market for 3D printers and services was worth $2.2 billion worldwide in 2012, up 29% from 2011.^[87] There are many applications for AM technologies, including architecture, construction (AEC), industrial design, automotive, aerospace,^[88] military, engineering, dental and medical industries, biotech (human tissue replacement), fashion, footwear, jewelry, eyewear, education, geographic information systems, food, and many other fields.

Additive manufacturing's earliest applications have been on the toolroom end of the manufacturing spectrum. For example, rapid prototyping was one of the earliest additive variants, and its mission was to reduce the lead time and cost of developing prototypes of new parts and devices, which was earlier only done with subtractive toolroom methods such as cnc milling and turning, and precision grinding, far more accurate than 3d printing with accuracy down to 0.00005" and creating better quality parts faster, but sometimes too expensive for low accuracy prototype parts.^[89] With technological advances in additive manufacturing, however, and the dissemination of those advances into the business world, additive methods are moving ever further into the production end of manufacturing in creative and sometimes unexpected ways.^[89] Parts that were formerly the sole province of subtractive methods can now in some cases be made more profitably via additive ones. In addition, new developments in RepRap technology allow the same device to perform both additive and subtractive manufacturing by swapping magnetic-mounted tool heads.^[90]

Cloud-based additive manufacturing

Additive manufacturing in combination with cloud computing technologies allows decentralized and geographically independent distributed production.^[91] Cloud-based additive manufacturing refers to a service-oriented networked manufacturing model in which service consumers are able to build parts through Infrastructure-as-a-Service (IaaS), Platform-as-a-Service (PaaS), Hardware-as-a-Service (HaaS), and Software-as-a-Service (SaaS).^[92][93][94] Distributed manufacturing as such is carried out by some enterprises; there is also a services like 3D Hubs that put people needing 3D printing in contact with owners of printers.^[95]

Some companies offer on-line 3D printing services to both commercial and private customers,^[96] working from 3D designs uploaded to the company website. 3D-printed designs are either shipped to the customer or picked up from the service provider.^[97]

Mass customization

Companies have created services where consumers can customize objects using simplified web based customisation software, and order the resulting items as 3D printed unique objects.^[98][99] This now allows consumers to create custom cases for their mobile phones.^[100] Nokia has released the 3D designs for its case so that owners can customize their own case and have it 3D printed.^[101]

Rapid manufacturing

Advances in RP technology have introduced materials that are appropriate for final manufacture, which has in turn introduced the possibility of directly manufacturing finished components. One advantage of 3D printing for rapid manufacturing lies in the relatively inexpensive production of small numbers of parts.

Rapid manufacturing is a new method of manufacturing and many of its processes remain unproven. 3D printing is now entering the field of rapid manufacturing and was identified as a "next level" technology by many experts in a 2009 report.^[102] One of the most promising processes looks to be the adaptation of selective laser sintering (SLS), or direct metal laser sintering (DMLS) some of the better-established rapid prototyping methods. As of 2006, however, these techniques were still very much in their infancy, with many obstacles to be overcome before RM could be considered a realistic manufacturing method.^[103] ,l,/.

Rapid prototyping

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 powdered metals, casting media (e.g. sand), plastics, paper or cartridges, and are used for rapid prototyping by universities and commercial companies.

Research

3D printing can be particularly useful in research labs due to its ability to make specialized, bespoke geometries. In 2012 a proof of principle project at the University of Glasgow, UK, showed that it is possible to use 3D printing techniques to assist in the production of chemical compounds. They first printed chemical reaction vessels, then used the printer to deposit reactants into them.^[104] They have produced new compounds to verify the validity of the process, but have not pursued anything with a particular application.^[104]

Food

Cornell Creative Machines Lab announced in 2012 that it was possible to produce customized food with 3D Hydrocolloid Printing.^[105] Additive manufacturing of food is currently being developed by squeezing out food, layer by layer, into three-dimensional objects. A large variety of foods are appropriate candidates, such as chocolate and candy, and flat foods such as crackers, pasta,^[106] and pizza.^[107] NASA has considered the versatility of the concept, awarding a contract to the Systems and Materials Research Consultancy to study the feasibility of printing food in space.^[108] One of the problem with food printing is the nature of the texture of a food. For example, foods that are not strong enough to be filed are not appropriate for 3D printing for now.

Medical applications

Professor Leroy Cronin of Glasgow University proposed in a 2012 TED Talk that it was possible to use chemical inks to print medicine.^[109] Similarly, 3D printing has been considered as a method of implanting stem cells capable of generating new tissues and organs in living humans.^[110]

Industrial applications

Apparel

3D printing has entered the world of clothing with fashion designers experimenting with 3D-printed bikinis, shoes, and dresses.^[111] In commercial production Nike is using 3D printing to prototype and manufacture the 2012 Vapor Laser Talon football shoe for players of American football, and New Balance is 3D manufacturing custom-fit shoes for athletes.^[111][112]

3D printing has come to the point where companies are printing consumer grade eyewear with on-demand custom fit and styling (although they cannot print the lenses). On-demand customization of glasses is possible with rapid prototyping.^[113]

However, comment has been made in academic circles as to the potential limitation of the human acceptance of such mass customised apparel items due to the potential reduction of brand value communication.^[114]

Vehicle

In early 2014, the Swedish supercar manufacturer, Koenigsegg, announced the One:1, a supercar that utilizes many components that were 3D printed. In the limited run of vehicles Koenigsegg produces, the One:1 has side-mirror internals, air ducts, titanium exhaust components, and even complete turbocharger assemblies that have been 3D printed as part of the manufacturing process.^[115]

Urbee is the name of the first car in the world car mounted using the technology 3D printing (his bodywork and his car windows were "printed"). Created in 2010 through the partnership between the US engineering group Kor Ecologic and the company Stratasys (manufacturer of printers Stratasys 3D), it is a hybrid vehicle with futuristic look.^{[116][117][118]}

In May 2015 Airbus announced that its new Airbus A350 XWB included over 1000 components manufactured by 3D printing.^[119]

3D printing is also being utilized by air forces to print spare parts for planes. In 2015, a Royal Air Force Eurofighter Typhoon fighter jet flew with printed parts. The United States Air Force has begun to work with 3D printers, and the Israeli Air Force has also purchased a 3D printer to print spare parts.^[120]

Construction

Until recent years models were built by hand, often taking a long time. Thus, architects are often forced to show their clients drawings of their projects. According to Erik Kinipper, clients usually need to see the product from all possible viewpoints in space to get a clearer picture of the design and make an informed decision. In order to get these scale models to clients in a small amount of time, architects and architecture firms tend to rely on 3D printing.^[121] Using 3D printing, these firms can reduce lead times of production by 50 to 80 percent, producing scale models up to 60 percent lighter than the machined part while being sturdy.^[122] Thus, the designs and the models are only limited by a person's imagination.

The improvements on accuracy, speed and quality of materials in 3D printing technology have opened new doors for it to move beyond the use of 3D printing in the modeling process and actually move it to manufacturing strategy. A good example is Dr. Behrokh Khoshnevis’ research at the University of Southern California which resulted in a 3D printer that can build a house in 24 hours .The process is called Contour Crafting. Khoshnevis, Russell, Kwon, & Bukkapatnam, define contour crafting as an additive manufacturing process which uses computer controlled systems to repeatedly lay down layers of materials such as concrete. Bushey also discussed Khoshnevis's robot which comes equipped with a nozzle that spews out concrete and can build a home based on a set computer pattern. Contour Crafting technology has great potential for automating the construction of whole structures as well as sub-components. Using this process, a single house or a colony of houses, each with possibly a different design, may be automatically constructed in a single run, embedded in each house all the conduits for electrical, plumbing and air-conditioning.^[123]

Firearms

In 2012, the US-based group Defense Distributed disclosed plans to "[design] a working plastic gun that could be downloaded and reproduced by anybody with a 3D printer."^[124][125] Defense Distributed has also designed a 3D printable AR-15 type rifle lower receiver (capable of lasting more than 650 rounds) and a 30 round M16 magazine The AR-15 has multiple receivers (both an upper and lower receiver), but the legally controlled part is the one that is serialized (the lower, in the AR-15's case). Soon after Defense Distributed succeeded in designing the first working blueprint to produce a plastic gun with a 3D printer in May 2013, the United States Department of State demanded that they remove the instructions from their website.^[126] After Defense Distributed released their plans, questions were raised regarding the effects that 3D printing and widespread consumer-level CNC machining^[127][128] may have on gun control effectiveness.^{[129][130][131][132]}

In 2014, a man from Japan became the first person in the world to be imprisoned for making 3D printed firearms.^[133] Yoshitomo Imura posted videos and blueprints of the gun online and was sentenced to jail for two years. Police found at least two guns in his household that were capable of firing bullets.^[133]

Medical

3D printing has been used to print patient specific implant and device for medical use. Successful operations include a titanium pelvis implanted into a British patient, titanium lower jaw transplanted to a Belgian patient,^[134] and a plastic tracheal splint for an American infant.^[135] The hearing aid and dental industries are expected to be the biggest area of future development using the custom 3D printing technology.^[136] In March 2014, surgeons in Swansea used 3D printed parts to rebuild the face of a motorcyclist who had been seriously injured in a road accident.^[137] Research is also being conducted on methods to bio-print replacements for lost tissue due to arthritis and cancer .

3D printing technology can now be used to make exact replicas of organs. The printer uses images from patients' MRI or CT scan images as a template and lays down layers of rubber or plastic.

Medical devices

In October 24, 2014, a five-year-old girl born without fully formed fingers on her left hand became the first child in the UK to have a prosthetic hand made with 3D printing technology. Her hand was designed by US-based E-nable, an open source design organisation which uses a network of volunteers to design and make prosthetics mainly for children. The prosthetic hand was based on a plaster cast made by her parents.^[138] A boy named Alex was also born with a missing arm from just above the elbow. The team was able to use 3D printing to upload an e-NABLE Myoelectric arm that runs off of servos and batteries that are actuated by the electromyography muscle. With the use of 3D printers, E-NABLE has so far distributed more than 400 plastic hands to children.

Printed prosthetics have been used in rehabilitation of crippled animals. In 2013, a 3D printed foot let a crippled duckling walk again.^[139] In 2014 a chihuahua born without front legs was fitted with a harness and wheels created with a 3D printer.^[140] 3D printed hermit crab shells let hermit crabs inhabit a new style home.^[141] A prosthetic beak was another tool developed by the use of 3D printing to help aid a bald eagle named Beauty, whose beak was severely mutilated from a shot in the face. Since 2014, commercially available titanium knee implants made with 3D printer for dogs have been used to restore the animal mobility. Over 10,000 dogs in Europe and United States have been treated after only one year.^[142]

In February 2015, FDA approved the marketing of a surgical bolt which facilitates less-invasive foot surgery and eliminates the need to drill through bone. The 3D printed titanium device, 'FastForward Bone Tether Plate' is approved to use in correction surgery to treat bunion.^[143] In October 2015, the group of Professor Andreas Herrmann at the University of Groningen has developed the first 3D printable resins with antimicrobial properties. Employing stereolithography, quaternary ammonium groups are incorporated into dental appliances that kill bacteria on contact. This type of material can be further applied in medical devices and implants.^[144]

Bio-printing

As of 2012, 3D bio-printing technology has been studied by biotechnology firms and academia for possible use in tissue engineering applications in which organs and body parts are built using inkjet techniques. In this process, layers of living cells are deposited onto a gel medium or sugar matrix and slowly built up to form three-dimensional structures including vascular systems.^[145] The first production system for 3D tissue printing was delivered in 2009, based on NovoGen bioprinting technology.^[146] Several terms have been used to refer to this field of research: organ printing, bio-printing, body part printing,^[147] and computer-aided tissue engineering, among others.^[148] The possibility of using 3D tissue printing to create soft tissue architectures for reconstructive surgery is also being explored.^[149]

In 2013, Chinese scientists began printing ears, livers and kidneys, with living tissue. Researchers in China have been able to successfully print human organs using specialized 3D bio printers that use living cells instead of plastic . Researchers at Hangzhou Dianzi University designed the "3D bio printer" dubbed the "Regenovo". Xu Mingen, Regenovo's developer, said that it takes the printer under an hour to produce either a mini liver sample or a four to five inch ear cartilage sample. Xu also predicted that fully functional printed organs may be possible within the next ten to twenty years.^[150][151] In the same year, researchers at the University of Hasselt, in Belgium had successfully printed a new jawbone for an 83-year-old Belgian woman.^[152]

Pills

The first pill manufactured by 3D printing was approved by the FDA in August 2015. Binder-jetting into a powder bed of the drug allows very porous pills to be produced, which enables high drug doses in a single pill which dissolves quickly and can be ingested easily.^[153] This has been demonstrated for Spritam, a reformulation of levetiracetam for the treatment of epilepsy.

Computers and robots

3D printing can also be used to make laptops and other computers and cases. For example, Novena and VIA OpenBook standard laptop cases. I.e. a Novena motherboard can be bought and be used in a printed VIA OpenBook case.^[154]

Open-source robots are built using 3D printers. Double Robotics grant access to their technology (an open SDK).^{[155][156][157]} On the other hand, 3&DBot is an Arduino 3D printer-robot with wheels^[158] and ODOI is a 3D printed humanoid robot.^[159]

Space

The Zero-G Printer, the first 3D printer designed to operate in zero gravity, was built under a joint partnership between NASA Marshall Space Flight Center (MSFC) and Made In Space, Inc.^[160] In September 2014, SpaceX delivered the zero-gravity 3D printer to the International Space Station (ISS). On December 19, 2014, NASA emailed CAD drawings for a socket wrench to astronauts aboard the ISS, who then printed the tool using its 3D printer. Applications for space offer the ability to print parts or tools on-site, as opposed to using rockets to bring along pre-manufactured items for space missions to human colonies on the moon, Mars, or elsewhere.^[161] The European Space Agency plans to deliver its new Portable On-Board 3D Printer (POP3D for short) to the International Space Station by June 2015, making it the second 3D printer in space.^[162][163]

Furthermore, the Sinterhab project is researching a lunar base constructed by 3D printing using lunar regolith as a base material. Instead of adding a binding agent to the regolith, researchers are experimenting with microwave sintering to create solid blocks from the raw material.^[164]

Similar researches and projects like these could allow faster construction for lower costs, and has been investigated for construction of off-Earth habitats.^[165][166]

Sociocultural applications

In 2005, a rapidly expanding hobbyist and home-use market was established with the inauguration of the open-source RepRap and Fab@Home projects. Virtually all home-use 3D printers released to-date have their technical roots in the ongoing RepRap Project and associated open-source software initiatives.^[167] In distributed manufacturing, one study has found^[168] that 3D printing could become a mass market product enabling consumers to save money associated with purchasing common household objects.^[73] For example, instead of going to a store to buy an object made in a factory by injection molding (such as a measuring cup or a funnel), a person might instead print it at home from a downloaded 3D model.

Art

In 2005, academic journals had begun to report on the possible artistic applications of 3D printing technology.^[169] By 2007 the mass media followed with an article in the Wall Street Journal^[170] and Time Magazine, listing a 3D printed design among their 100 most influential designs of the year.^[171] During the 2011 London Design Festival, an installation, curated by Murray Moss and focused on 3D Printing, was held in the Victoria and Albert Museum (the V&A). The installation was called Industrial Revolution 2.0: How the Material World will Newly Materialize.^[172]

Some of the recent developments in 3D printing were revealed at the 3DPrintshow in London, which took place in November 2013 and 2014. The art section had in exposition artworks made with 3D printed plastic and metal. Several artists such as Joshua Harker, Davide Prete, Sophie Kahn, Helena Lukasova, Foteini Setaki showed how 3D printing can modify aesthetic and art processes. One part of the show focused on ways in which 3D printing can advance the medical field. The underlying theme of these advances was that these printers can be used to create parts that are printed with specifications to meet each individual. This makes the process safer and more efficient. One of these advances is the use of 3D printers to produce casts that are created to mimic the bones that they are supporting. These custom-fitted casts are open, which allow the wearer to scratch any itches and also wash the damaged area. Being open also allows for open ventilation. One of the best features is that they can be recycled to create more casts.^[173]

3D printing is becoming more popular in the customisable gifts industry, with products such as personalized mobile phone cases and dolls,^[174] as well as 3D printed chocolate.^[175]

The use of 3D scanning technologies allows the replication of real objects without the use of moulding techniques that in many cases can be more expensive, more difficult, or too invasive to be performed, particularly for precious or delicate cultural heritage artifacts^[176] where direct contact with the moulding substances could harm the original object's surface.

Critical making refers to the hands on productive activities that link digital technologies to society. It is invented to bridge the gap between creative physical and conceptual exploration.^[177] The term was popularized by Matt Ratto, an Assistant Professor and director of the Critical Making lab in the Faculty of Information at the University of Toronto. Ratto describes one of the main goals of critical as "to use material forms of engagement with technologies to supplement and extend critical reflection and, in doing so, to reconnect our lived experiences with technologies to social and conceptual critique".^[178] The main focus of critical making is open design,^[179] which includes, in addition to 3D printing technologies, also other digital software and hardware. People usually reference spectacular design when explaining critical making.^[180]

Communication

Employing additive layer technology offered by 3D printing, Terahertz devices which act as waveguides, couplers and bends have been created. The complex shape of these devices could not be achieved using conventional fabrication techniques. Commercially available professional grade printer EDEN 260V was used to create structures with minimum feature size of 100 µm. The printed structures were later DC sputter coated with gold (or any other metal) to create a Terahertz Plasmonic Device.^[181]

Domestic use

As of 2012, domestic 3D printing was mainly practiced by hobbyists and enthusiasts. However, little was used for practical household applications, for example, ornamental objects. Some practical examples include a working clock^[182] and gears printed for home woodworking machines among other purposes.^[183] Web sites associated with home 3D printing tended to include backscratchers, coat hooks, door knobs, etc.^[184]

The open source Fab@Home project^[68] has developed printers for general use. They have been used in research environments to produce chemical compounds with 3D printing technology, including new ones, initially without immediate application as proof of principle.^[104] The printer can print with anything that can be dispensed from a syringe as liquid or paste. The developers of the chemical application envisage both industrial and domestic use for this technology, including enabling users in remote locations to be able to produce their own medicine or household chemicals.^[185][186]

3D printing is now working its way into households, and more and more children are being introduced to the concept of 3D printing at earlier ages. The prospects of 3D printing are growing, and as more people have access to this new innovation, new uses in households will emerge.^[187]

The OpenReflex SLR film camera was developed for 3D printing as an open-source student project.^[188]

Education and research

3D printing, and open source RepRap 3D printers in particular, are the latest technology making inroads into the classroom.^{[189][190][191]} 3D printing allows students to create prototypes of items without the use of expensive tooling required in subtractive methods. Students design and produce actual models they can hold. The classroom environment allows students to learn and employ new applications for 3D printing.^[192] RepRaps, for example, have already been used for an educational mobile robotics platform.^[193]

Some authors have claimed that RepRap 3D printers offer an unprecedented "revolution" in STEM education.^[194] The evidence for such claims comes from both the low cost ability for rapid prototyping in the classroom by students, but also the fabrication of low-cost high-quality scientific equipment from open hardware designs forming open-source labs.^[195] Engineering and design principles are explored as well as architectural planning. Students recreate duplicates of museum items such as fossils and historical artifacts for study in the classroom without possibly damaging sensitive collections. Other students interested in graphic designing can construct models with complex working parts. 3D printing gives students a new perspective with topographic maps. Science students can study cross-sections of internal organs of the human body and other biological specimens. And chemistry students can explore 3D models of molecules and the relationship within chemical compounds.^[196]

According to a recent paper by Kostakis et al.,^[197] 3D printing and design can electrify various literacies and creative capacities of children in accordance with the spirit of the interconnected, information-based world.

Future applications for 3D printing might include creating open-source scientific equipment.^[195][198]

Environmental use

In Bahrain, large-scale 3D printing using a sandstone-like material has been used to create unique coral-shaped structures, which encourage coral polyps to colonize and regenerate damaged reefs. These structures have a much more natural shape than other structures used to create artificial reefs, and, unlike concrete, are neither acid nor alkaline with neutral pH.^[199]

Cultural Heritage

In the last several years 3D printing has been intensively used by in the cultural heritage field for preservation, restoration and dissemination purposes.^[200] Many Europeans and North American Museums have purchased 3D printers and actively recreate missing pieces of their of relics.^[201]

The Metropolitan Museum of Art and the British Museum have started using their 3D printers to create museum souvenirs that are available in the museum shops.^[202] Other museums, like the National Museum of Military History and Varna Historical Museum, have gone further and sell through the online platform Threeding digital models of their artifacts in 3D printing friendly file format, which everyone can 3D print at home.^[203]

Specialty materials

Consumer grade 3D printing has resulted in new materials that have been developed specifically for 3D printers. For example, filament materials have been developed to imitate wood, in its appearance as well as its texture. Furthermore, new technologies, such as infusing carbon fiber^[204] into printable plastics, allowing for a stronger, lighter material. In addition to new structural materials that have been developed due to 3D printing, new technologies have allowed for patterns to be applied directly to 3D printed parts. Iron oxide-free Portland cement powder has been used to create architectural structures up to 9 feet in height.^{[205][206][207]}

Legal aspects

Intellectual property

3D printing has existed for decades within certain manufacturing industries where many legal regimes, including patents, industrial design rights, copyright, and trademark may apply. However, there is not much jurisprudence to say how these laws will apply if 3D printers become mainstream and individuals and hobbyist communities begin manufacturing items for personal use, for non-profit distribution, or for sale.

Any of the mentioned legal regimes may prohibit the distribution of the designs used in 3D printing, or the distribution or sale of the printed item. To be allowed to do these things, where an active intellectual property was involved, a person would have to contact the owner and ask for a licence, which may come with conditions and a price. However, many patent, design and copyright laws contain a standard limitation or exception for 'private', 'non-commercial' use of inventions, designs or works of art protected under intellectual property (IP). That standard limitation or exception may leave such private, non-commercial uses outside the scope of IP rights.

Patents cover inventions including processes, machines, manufactures, and compositions of matter and have a finite duration which varies between countries, but generally 20 years from the date of application. Therefore, if a type of wheel is patented, printing, using, or selling such a wheel could be an infringement of the patent.^[208]

Copyright covers an expression^[209] in a tangible, fixed medium and often lasts for the life of the author plus 70 years thereafter.^[210] If someone makes a statue, they may have copyright on the look of that statue, so if someone sees that statue, they cannot then distribute designs to print an identical or similar statue.

When a feature has both artistic (copyrightable) and functional (patentable) merits, when the question has appeared in US court, the courts have often held the feature is not copyrightable unless it can be separated from the functional aspects of the item.^[210] In other countries the law and the courts may apply a different approach allowing, for example, the design of a useful device to be registered (as a whole) as an industrial design on the understanding that, in case of unauthorized copying, only the non-functional features may be claimed under design law whereas any technical features could only be claimed if covered by a valid patent.

Gun legislation and administration

The US Department of Homeland Security and the Joint Regional Intelligence Center released a memo stating that "significant advances in three-dimensional (3D) printing capabilities, availability of free digital 3D printable files for firearms components, and difficulty regulating file sharing may present public safety risks from unqualified gun seekers who obtain or manufacture 3D printed guns," and that "proposed legislation to ban 3D printing of weapons may deter, but cannot completely prevent their production. Even if the practice is prohibited by new legislation, online distribution of these 3D printable files will be as difficult to control as any other illegally traded music, movie or software files."^[211]

Internationally, where gun controls are generally stricter than in the United States, some commentators have said the impact may be more strongly felt, as alternative firearms are not as easily obtainable.^[212] European officials have noted that producing a 3D printed gun would be illegal under their gun control laws,^[213] and that criminals have access to other sources of weapons, but noted that as the technology improved the risks of an effect would increase.^[214][215] Downloads of the plans from the UK, Germany, Spain, and Brazil were heavy.^[216][217]

Attempting to restrict the distribution over the Internet of gun plans has been likened to the futility of preventing the widespread distribution of DeCSS which enabled DVD ripping.^{[218][219][220][221]} After the US government had Defense Distributed take down the plans, they were still widely available via The Pirate Bay and other file sharing sites.^[222] Some US legislators have proposed regulations on 3D printers, to prevent them being used for printing guns.^[223][224] 3D printing advocates have suggested that such regulations would be futile, could cripple the 3D printing industry, and could infringe on free speech rights, with early pioneer of 3D printing Professor Hod Lipson suggesting that gunpowder could be controlled instead.^{[225][226][227][228][229][230][231]}

Impact

Additive manufacturing, starting with today's infancy period, requires manufacturing firms to be flexible, ever-improving users of all available technologies to remain competitive. Advocates of additive manufacturing also predict that this arc of technological development will counter globalization, as end users will do much of their own manufacturing rather than engage in trade to buy products from other people and corporations.^[5] The real integration of the newer additive technologies into commercial production, however, is more a matter of complementing traditional subtractive methods rather than displacing them entirely.^[232]

Social change

Since the 1950s, a number of writers and social commentators have speculated in some depth about the social and cultural changes that might result from the advent of commercially affordable additive manufacturing technology.^[233] Amongst the more notable ideas to have emerged from these inquiries has been the suggestion that, as more and more 3D printers start to enter people's homes, so the conventional relationship between the home and the workplace might get further eroded.^[234] Likewise, it has also been suggested that, as it becomes easier for businesses to transmit designs for new objects around the globe, so the need for high-speed freight services might also become less.^[235] Finally, given the ease with which certain objects can now be replicated, it remains to be seen whether changes will be made to current copyright legislation so as to protect intellectual property rights with the new technology widely available.

As 3D printers became more accessible to consumers, online social platforms have developed to support the community.^[236] This includes websites that allow users to access information such as how to build a 3D printer, as well as social forums that discuss how to improve 3D print quality and discuss 3D printing news, as well as social media websites that are dedicated to share 3D models.^{[237][238][239]} RepRap is a wiki based website that was created to hold all information on 3d printing, and has developed into a community that aims to bring 3D printing to everyone. Furthermore, there are other sites such as Pinshape, Thingiverse and MyMiniFactory, which was created initially to allow users to post 3D files for anyone to print, allowing for decreased transaction cost of sharing 3D files. These websites have allowed for greater social interaction between users, creating communities dedicated around 3D printing.

Some ^{[240][241][242]} call attention to the conjunction of Commons-based peer production with 3D printing and other low-cost manufacturing techniques. The self-reinforced fantasy of a system of eternal growth can be overcome with the development of economies of scope, and here, the civil society can play an important role contributing to the raising of the whole productive structure to a higher plateau of more sustainable and customized productivity.^[240] Further, it is true that many issues, problems and threats rise due to the large democratization of the means of production, and especially regarding the physical ones.^[240] For instance, the recyclability of advanced nanomaterials is still questioned; weapons manufacturing could become easier; not to mention the implications on counterfeiting ^[243] and on IP.^[244] It might be maintained that in contrast to the industrial paradigm whose competitive dynamics were about economies of scale, Commons-based peer production and 3D printing could develop economies of scope. While the advantages of scale rest on cheap global transportation, the economies of scope share infrastructure costs (intangible and tangible productive resources), taking advantage of the capabilities of the fabrication tools.^[240] And following Neil Gershenfeld ^[245] in that "some of the least developed parts of the world need some of the most advanced technologies", Commons-based peer production and 3D printing may offer the necessary tools for thinking globally but act locally in response to certain problems and needs.

Larry Summers wrote about the "devastating consequences" of 3D printing and other technologies (robots, artificial intelligence, etc.) for those who perform routine tasks. In his view, "already there are more American men on disability insurance than doing production work in manufacturing. And the trends are all in the wrong direction, particularly for the less skilled, as the capacity of capital embodying artificial intelligence to replace white-collar as well as blue-collar work will increase rapidly in the years ahead." Summers recommends more vigorous cooperative efforts to address the "myriad devices" (e.g., tax havens, bank secrecy, money laundering, and regulatory arbitrage) enabling the holders of great wealth to "avoid paying" income and estate taxes, and to make it more difficult to accumulate great fortunes without requiring "great social contributions" in return, including: more vigorous enforcement of anti-monopoly laws, reductions in "excessive" protection for intellectual property, greater encouragement of profit-sharing schemes that may benefit workers and give them a stake in wealth accumulation, strengthening of collective bargaining arrangements, improvements in corporate governance, strengthening of financial regulation to eliminate subsidies to financial activity, easing of land-use restrictions that may cause the real estate of the rich to keep rising in value, better training for young people and retraining for displaced workers, and increased public and private investment in infrastructure development—e.g., in energy production and transportation.^[246]

Michael Spence wrote that "Now comes a … powerful, wave of digital technology that is replacing labor in increasingly complex tasks. This process of labor substitution and disintermediation has been underway for some time in service sectors—think of ATMs, online banking, enterprise resource planning, customer relationship management, mobile payment systems, and much more. This revolution is spreading to the production of goods, where robots and 3D printing are displacing labor." In his view, the vast majority of the cost of digital technologies comes at the start, in the design of hardware (e.g. 3D printers) and, more important, in creating the software that enables machines to carry out various tasks. "Once this is achieved, the marginal cost of the hardware is relatively low (and declines as scale rises), and the marginal cost of replicating the software is essentially zero. With a huge potential global market to amortize the upfront fixed costs of design and testing, the incentives to invest [in digital technologies] are compelling." Spence believes that, unlike prior digital technologies, which drove firms to deploy underutilized pools of valuable labor around the world, the motivating force in the current wave of digital technologies "is cost reduction via the replacement of labor." For example, as the cost of 3D printing technology declines, it is "easy to imagine" that production may become "extremely" local and customized. Moreover, production may occur in response to actual demand, not anticipated or forecast demand. Spence believes that labor, no matter how inexpensive, will become a less important asset for growth and employment expansion, with labor-intensive, process-oriented manufacturing becoming less effective, and that re-localization will appear in both developed and developing countries. In his view, production will not disappear, but it will be less labor-intensive, and all countries will eventually need to rebuild their growth models around digital technologies and the human capital supporting their deployment and expansion. Spence writes that "the world we are entering is one in which the most powerful global flows will be ideas and digital capital, not goods, services, and traditional capital. Adapting to this will require shifts in mindsets, policies, investments (especially in human capital), and quite possibly models of employment and distribution."^[247]

Forbes investment pundits have predicted that 3D printing may lead to a resurgence of American Manufacturing, citing the small, creative companies that comprise the current industry landscape, and the lack of the necessary complex infrastructure in typical outsource markets.^[248]

See also

References

Further reading

• "Results of Make Magazine's 2015 3D Printer Shootout". docs.google.com. Retrieved 1 June 2015. 
• "Evaluation Protocol for Make Magazine's 2015 3D Printer Shootout". makezine.com. Retrieved 1 June 2015. 
• Vincent; Earls, Alan R. (February 2011). "Origins: A 3D Vision Spawns Stratasys, Inc.". Today's Machining World (Oak Forest, Illinois, USA: Screw Machine World Inc.) 7 (1): 24–25. 
• "Heat Beds in 3D Printing – Advantages and Equipment". Boots Industries. Retrieved 7 September 2015. 
• Albert, Mark [Editor in Chief] (17 January 2011). "Subtractive plus additive equals more than ( − + +=> ): subtractive and additive processes can be combined to develop innovative manufacturing methods that are superior to conventional methods ['Mark: My Word' column – Editor's Commentary]". Modern Machine Shop (Cincinnati, Ohio, USA: Gardner Publications Inc.) 83 (9): 14. 
• Stephens, B.; Azimi, P.; El Orch, Z.; Ramos, T. (2013). "Ultrafine particle emissions from desktop 3D printers". Atmospheric Environment 79: 334. doi:10.1016/j.atmosenv.2013.06.050. 
• 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

Wikimedia Commons has media related to 3D printing.

• Rapid prototyping websites at DMOZ

3D printing technologies Vat photopolymerization Continuous liquid interface production • Film transfer imaging • Solid ground curing • Stereolithography Material jetting Liquid metal jet printing • Plastic jet printing • Multi jet modeling Binder jetting Powder bed and inkjet head 3D printing Material extrusion Fused deposition modeling • Robocasting Powder bed fusion Direct metal laser sintering • Electron beam melting • Laser sintering of gold • Selective heat sintering • Selective laser melting • Selective laser sintering Sheet lamination Laminated object manufacturing • Ultrasonic consolidation Directed energy deposition Electron beam freeform fabrication • Laser engineered net shaping Building printing Contour crafting • D-Shape Related topics 3D bioprinting • 3D printing marketplace • Digital modeling and fabrication • Rapid prototyping • RepRap project

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