6/13/22, 9:34 AM
`
`3D printing - Wikipedia
`
`3D printing
`
`3D printing or additive manufacturing is the construction of
`a three-dimensional object from a CAD model or a digital 3D
`model.[1] It can be done in a variety of processes in which material
`is deposited, joined or solidified under computer control,[2] with
`material being added together (such as plastics, liquids or powder
`grains being fused), typically layer by layer.
`
`In the 1980s, 3D printing techniques were considered suitable
`only for the production of functional or aesthetic prototypes, and a
`more appropriate term for it at the time was rapid prototyping.[3]
`As of 2019, the precision, repeatability, and material range of 3D
`printing have increased to the point that some 3D printing
`processes are considered viable as an industrial-production
`technology, whereby the term additive manufacturing can be
`used synonymously with 3D printing.[4] One of the key
`advantages of 3D printing is the ability to produce very complex
`shapes or geometries that would be otherwise impossible to
`construct by hand, including hollow parts or parts with internal
`truss structures to reduce weight. Fused deposition modeling
`(FDM), which uses a continuous filament of a thermoplastic
`material, is the most common 3D printing process in use as of
`2020.[5]
`
`Contents
`Terminology
`History
`1940s and 1950s
`1970s
`1980s
`1990s
`2000s
`2010s
`2020s
`General principles
`Modeling
`Printing
`Finishing
`Materials
`Multi-material 3D printing
`
`A three-dimensional printer
`
`Timelapse of a three-
`dimensional printer in action
`
`https://en.wikipedia.org/wiki/3D_printing
`
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`3D printing - Wikipedia
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`6/13/22, 9:34 AM
`4D printing
`Processes and printers
`Applications
`Food industry
`Fashion industry
`Transportation industry
`Firearm industry
`Health sector
`Education sector
`Cultural heritage and museum-based digital twin
`Recent other applications
`Legal aspects
`Intellectual property
`Gun legislation and administration
`Aerospace regulation
`Health and safety
`Impact
`Social change
`Environmental change
`See also
`References
`Further reading
`External links
`
`Terminology
`
`The umbrella term additive manufacturing (AM) gained popularity in the 2000s,[6] inspired by the
`theme of material being added together (in any of various ways). In contrast, the term subtractive
`manufacturing appeared as a retronym for the large family of machining processes with material
`removal as their common process. The term 3D printing still referred only to the polymer
`technologies in most minds, and the term AM was more likely to be used in metalworking and end-
`use part production contexts than among polymer, inkjet, or stereolithography enthusiasts. Inkjet was
`the least familiar technology even though it was invented in 1950 and poorly understood because of
`its complex nature. The earliest inkjets were used as recorders and not printers. As late as the 1970s
`the term recorder was associated with inkjet. Continuous Inkjet later evolved to On-Demand or Drop-
`On-Demand Inkjet. Inkjets were single nozzle at the start; they may now have as many as thousands
`of nozzles for printing in each pass over a surface.
`
`By the early 2010s, the terms 3D printing and additive manufacturing evolved senses in which they
`were alternate umbrella terms for additive technologies, one being used in popular language by
`consumer-maker communities and the media, and the other used more formally by industrial end-use
`part producers, machine manufacturers, and global technical standards organizations. Until recently,
`the term 3D printing has been associated with machines low in price or in capability.[7] 3D printing
`and additive manufacturing reflect that the technologies share the theme of material addition or
`
`https://en.wikipedia.org/wiki/3D_printing
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`joining throughout a 3D work envelope under automated control. Peter Zelinski, the editor-in-chief of
`Additive Manufacturing magazine, pointed out in 2017 that the terms are still often synonymous in
`casual usage,[8] but some manufacturing industry experts are trying to make a distinction whereby
`additive manufacturing comprises 3D printing plus other technologies or other aspects of a
`manufacturing process.[8]
`
`Other terms that have been used as synonyms or hypernyms have included 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). Such
`application of the adjectives rapid and on-demand to the noun manufacturing was novel in the
`2000s reveals the prevailing mental model of the long industrial era in which almost all production
`manufacturing involved long lead times for laborious tooling development. Today, the term
`subtractive has not replaced the term machining, instead complementing it when a term that covers
`any removal method is needed. Agile tooling is the use of modular means to design tooling that is
`produced by additive manufacturing or 3D printing methods to enable quick prototyping and
`responses to tooling and fixture needs. Agile tooling uses a cost-effective and high-quality method to
`quickly respond to customer and market needs, and it can be used in hydro-forming, stamping,
`injection molding and other manufacturing processes.
`History
`
`1940s and 1950s
`
`The general concept of and procedure to be used in 3D-printing was first described by Murray
`Leinster in his 1945 short story Things Pass By "But this constructor is both efficient and flexible. I
`feed magnetronic plastics — the stuff they make houses and ships of nowadays — into this moving
`arm. It makes drawings in the air following drawings it scans with photo-cells. But plastic comes out
`of the end of the drawing arm and hardens as it comes ... following drawings only" [9]
`
`It was also described by Raymond F. Jones in his story, "Tools of the Trade," published in the
`November 1950 issue of Astounding Science Fiction magazine. He referred to it as a "molecular spray"
`in that story.
`
`1970s
`
`In 1971, Johannes F Gottwald patented the Liquid Metal Recorder, U.S. Patent 3596285A (https://pat
`ents.google.com/patent/US3596285A), a continuous Inkjet metal material device to form a
`removable metal fabrication on a reusable surface for immediate use or salvaged for printing again by
`remelting. This appears to be the first patent describing 3D printing with rapid prototyping and
`controlled on-demand manufacturing of patterns.
`
`The patent states "As used herein the term printing is not intended in a limited sense but includes
`writing or other symbols, character or pattern formation with an ink. The term ink as used in is
`intended to include not only dye or pigment-containing materials, but any flowable substance or
`composition suited for application to the surface for forming symbols, characters, or patterns of
`intelligence by marking. The preferred ink is of a Hot melt type. The range of commercially available
`ink compositions which could meet the requirements of the invention are not known at the present
`time. However, satisfactory printing according to the invention has been achieved with the conductive
`metal alloy as ink."
`https://en.wikipedia.org/wiki/3D_printing
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`"But in terms of material requirements for such large and continuous displays, if consumed at
`theretofore known rates, but increased in proportion to increase in size, the high cost would severely
`limit any widespread enjoyment of a process or apparatus satisfying the foregoing objects."
`
`"It is therefore an additional object of the invention to minimize use to materials in a process of the
`indicated class."
`
`"It is a further object of the invention that materials employed in such a process be salvaged for
`reuse."
`
`"According to another aspect of the invention, a combination for writing and the like comprises a
`carrier for displaying an intelligence pattern and an arrangement for removing the pattern from the
`carrier."
`
`In 1974, David E. H. Jones laid out the concept of 3D printing in his regular column Ariadne in the
`journal New Scientist.[10][11]
`
`1980s
`
`Early additive manufacturing equipment and materials were developed in the 1980s.[12]
`
`In April 1980, Hideo Kodama of Nagoya Municipal Industrial Research Institute invented two
`additive methods for fabricating three-dimensional plastic models with photo-hardening thermoset
`polymer, where the UV exposure area is controlled by a mask pattern or a scanning fiber
`transmitter.[13] He filed a patent for this XYZ plotter, which was published on 10 November 1981. (JP
`S56-144478 (https://www.j-platpat.inpit.go.jp/c1800/PU/JP-S56-144478/1D0ADD2064383A29D55
`152F0210F025DEFC37B25B70242A69D2F88F6F3A29A10/11/en)).[14] His research results as
`journal papers were published in April and November in 1981.[15][16] However, there was no reaction
`to the series of his publications. His device was not highly evaluated in the laboratory and his boss did
`not show any interest. His research budget was just 60,000 yen or $545 a year. Acquiring the patent
`rights for the XYZ plotter was abandoned, and the project was terminated.
`
`A US 4323756 patent, method of fabricating articles by sequential deposition, granted on 6 April
`1982 to Raytheon Technologies Corp describes using hundreds or thousands of 'layers' of powdered
`metal and a laser energy source and represents an early reference to forming "layers" and the
`fabrication of articles on a substrate.
`
`On 2 July 1984, American entrepreneur Bill Masters filed a patent for his computer automated
`4665492
`(US
`manufacturing
`process
`and
`system
`(https://patents.google.com/patent/US4665492)).[17] This filing is on record at the USPTO as the
`first 3D printing patent in history; it was the first of three patents belonging to Masters that laid the
`foundation for the 3D printing systems used today.[18][19]
`
`On 16 July 1984, Alain Le Méhauté, Olivier de Witte, and Jean Claude André filed their patent for the
`stereolithography process.[20] The application of the French inventors was abandoned by the French
`General Electric Company (now Alcatel-Alsthom) and CILAS (The Laser Consortium).[21] The claimed
`reason was "for lack of business perspective".[22]
`
`In 1983, Robert Howard started R.H. Research, later named Howtek, Inc. in Feb 1984 to develop a
`color inkjet 2D printer, Pixelmaster, commercialized in 1986, using Thermoplastic (hot-melt) plastic
`ink.[23] A team was put together, 6 members[23] from Exxon Office Systems, Danbury Systems
`https://en.wikipedia.org/wiki/3D_printing
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`Division, an inkjet printer startup and some members of Howtek, Inc group who became popular
`figures in the 3D printing industry. One Howtek member, Richard Helinski (patent US5136515A,
`Method and Means for constructing three-dimensional articles by particle deposition, application
`11/07/1989 granted 8/04/1992) formed a New Hampshire company C.A.D-Cast, Inc, name later
`changed to Visual Impact Corporation (VIC) on 8/22/1991. A prototype of the VIC 3D printer for this
`company is available with a video presentation showing a 3D model printed with a single nozzle
`inkjet. Another employee Herbert Menhennett formed a New Hampshire company HM Research in
`1991 and introduced the Howtek, Inc, inkjet technology and thermoplastic materials to Royden
`Sanders of SDI and Bill Masters of Ballistic Particle Manufacturing (BPM) where he worked for a
`number of years. Both BPM 3D printers and SPI 3D printers use Howtek, Inc style Inkjets and
`Howtek, Inc style materials. Royden Sanders licensed the Helinksi patent prior to manufacturing the
`Modelmaker 6 Pro at Sanders prototype, Inc (SPI) in 1993. James K. McMahon who was hired by
`Howtek, Inc to help develop the inkjet, later worked at Sanders Prototype and now operates Layer
`Grown Model Technology, a 3D service provider specializing in Howtek single nozzle inkjet and SDI
`printer support. James K. McMahon worked with Steven Zoltan, 1972 drop-on-demand inkjet
`inventor, at Exxon and has a patent in 1978 that expanded the understanding of the single nozzle
`design inkjets (Alpha jets) and help perfect the Howtek, Inc hot-melt inkjets. This Howtek hot-melt
`thermoplastic technology is popular with metal investment casting, especially in the 3D printing
`jewelry industry.[24] Sanders (SDI) first Modelmaker 6Pro customer was Hitchner Corporations,
`Metal Casting Technology, Inc in Milford, NH a mile from the SDI facility in late 1993-1995 casting
`golf clubs and auto engine parts.
`
`On 8 August 1984 a patent, US4575330, assigned to UVP, Inc., later assigned to Chuck Hull of 3D
`Systems Corporation[25] was filed, his own patent for a stereolithography fabrication system, in which
`individual laminae or layers are added by curing photopolymers with impinging radiation, particle
`bombardment, chemical reaction or just 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,".[26][27] Hull's contribution was the STL (Stereolithography) file format and the digital slicing
`and infill strategies common to many processes today. In 1986, Charles "Chuck" Hull was granted a
`patent for this system, and his company, 3D Systems Corporation was formed and it released the first
`commercial 3D printer, the SLA-1,[28] later in 1987 or 1988.
`
`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, developed in 1988 by S.
`Scott Crump and commercialized by his company Stratasys, which marketed its first FDM machine in
`1992.[24]
`
`Owning a 3D printer in the 1980s cost upwards of $300,000 ($650,000 in 2016 dollars).[29]
`
`1990s
`
`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, all metalworking was done by processes that are now called non-additive (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 with a toolpath was
`associated in metalworking only with processes that removed metal (rather than adding it), such as
`CNC milling, CNC EDM, and many others. But the automated techniques that added metal, which
`would later be called additive manufacturing, were beginning to challenge that assumption. By the
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`mid-1990s, new techniques for material deposition were developed at Stanford and Carnegie Mellon
`University, including microcasting[30] and sprayed materials.[31] Sacrificial and support materials had
`also become more common, enabling new object geometries.[32]
`
`The term 3D printing originally referred to a powder bed process employing standard and custom
`inkjet print heads, developed at MIT by Emanuel Sachs in 1993 and commercialized by Soligen
`Technologies, Extrude Hone Corporation, and Z Corporation.
`
`The year 1993 also saw the start of an inkjet 3D printer company initially named Sanders Prototype,
`Inc and later named Solidscape, introducing a high-precision polymer jet fabrication system with
`soluble support structures, (categorized as a "dot-on-dot" technique).[24]
`
`In 1995 the Fraunhofer Society developed the selective laser melting process.
`
`2000s
`
`Fused Deposition Modeling (FDM) printing process patents expired in 2009.[33]
`
`2010s
`
`As the various additive processes matured, it became clear that soon metal removal would no longer
`be the only metalworking process done through a tool or head moving through a 3D work envelope,
`transforming a mass of raw material into a desired shape layer by layer. The 2010s were the first
`decade in which metal end use parts such as engine brackets[34] and large nuts[35] would be grown
`(either before or instead of machining) in job production rather than obligately being machined from
`bar stock or plate. It is still the case that casting, fabrication, stamping, and machining are more
`prevalent than additive manufacturing in metalworking, but AM is now beginning to make significant
`inroads, and with the advantages of design for additive manufacturing, it is clear to engineers that
`much more is to come.
`
`One place that AM is making a significant inroad is in the aviation industry. With nearly 3.8 billion air
`travelers in 2016,[36] the demand for fuel efficient and easily produced jet engines has never been
`higher. For large OEMs (original equipment manufacturers) like Pratt and Whitney (PW) and General
`Electric (GE) this means looking towards AM as a way to reduce cost, reduce the number of
`nonconforming parts, reduce weight in the engines to increase fuel efficiency and find new, highly
`complex shapes that would not be feasible with the antiquated manufacturing methods. One example
`of AM integration with aerospace was in 2016 when Airbus was delivered the first of GE's LEAP
`engine. This engine has integrated 3D printed fuel nozzles giving them a reduction in parts from 20 to
`1, a 25% weight reduction and reduced assembly times.[37] A fuel nozzle is the perfect in road for
`additive manufacturing in a jet engine since it allows for optimized design of the complex internals
`and it is a low stress, non-rotating part. Similarly, in 2015, PW delivered their first AM parts in the
`PurePower PW1500G to Bombardier. Sticking to low stress, non-rotating parts, PW selected the
`compressor stators and synch ring brackets [38] to roll out this new manufacturing technology for the
`first time. While AM is still playing a small role in the total number of parts in the jet engine
`manufacturing process, the return on investment can already be seen by the reduction in parts, the
`rapid production capabilities and the "optimized design in terms of performance and cost".[39]
`
`As technology matured, several authors had begun to speculate that 3D printing could aid in
`sustainable development in the developing world.[40]
`
`https://en.wikipedia.org/wiki/3D_printing
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`In 2012, Filabot developed a system for closing the loop[41] with plastic and allows for any FDM or
`FFF 3D printer to be able to print with a wider range of plastics.
`
`In 2014, Benjamin S. Cook and Manos M. Tentzeris demonstrate the first multi-material, vertically
`integrated printed electronics additive manufacturing platform (VIPRE) which enabled 3D printing of
`functional electronics operating up to 40 GHz.[42]
`
`As the price of printers started to drop people interested in this technology had more access and
`freedom to make what they wanted. The price as of 2014 was still high with the cost being over
`$2,000, yet this still allowed hobbyists an entrance into printing outside of production and industry
`methods.[43]
`
`The term "3D printing" originally referred to a process that deposits a binder material onto a powder
`bed with inkjet printer heads layer by layer. More recently, the popular vernacular has started using
`the term to encompass a wider variety of additive-manufacturing techniques such as electron-beam
`additive manufacturing and selective laser melting. The United States and global technical standards
`use the official term additive manufacturing for this broader sense.
`
`The most-commonly used 3D printing process (46% as of 2018) is a material extrusion technique
`called fused deposition modeling, or FDM.[5] While FDM technology was invented after the other two
`most popular technologies, stereolithography (SLA) and selective laser sintering (SLS), FDM is
`typically the most inexpensive of the three by a large margin, which lends to the popularity of the
`process.
`
`2020s
`
`As of 2020, 3D printers have reached the level of quality and price that allows most people to enter
`the world of 3D printing. In 2020 decent quality printers can be found for less than US$200 for entry
`level machines. These more affordable printers are usually fused deposition modeling (FDM)
`printers.[44] In November 2021 a British patient named Steve Verze received the world's first fully 3D-
`printed prosthetic eye from the Moorfields Eye Hospital in London.[45] [46]
`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
`result in relatively fewer errors than other methods. Errors in 3D
`printable models can be
`identified and corrected before
`printing.[47] 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.
`
`CAD model used for 3D printing
`
`https://en.wikipedia.org/wiki/3D_printing
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`CAD models can be saved in the stereolithography file format (STL), a de
`facto CAD file format for additive manufacturing that stores data based
`on triangulations of the surface of CAD models. STL is not tailored for
`additive manufacturing because it generates large file sizes of topology
`optimized parts and lattice structures due to the large number of surfaces
`involved. A newer CAD file format, the Additive Manufacturing File
`format (AMF) was introduced in 2011 to solve this problem. It stores
`information using curved triangulations.[48]
`
`Printing
`
`Before printing a 3D model from an STL file, it must first be examined for
`errors. Most CAD applications produce errors in output STL files,[49][50]
`of the following types:
`
`3D models can be
`generated from 2D pictures
`taken at a 3D photo booth.
`
`1. holes
`2. faces normals
`3. self-intersections
`4. noise shells
`5. manifold errors[51]
`6. overhang issues [52]
`
`A step in the STL generation known as "repair" fixes such problems in the original model.[53][54]
`Generally STLs that have been produced from a model obtained through 3D scanning often have
`more of these errors [55] as 3D scanning is often achieved by point to point acquisition/mapping. 3D
`reconstruction often includes errors.[56]
`
`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).[57] 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).[58] 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. For that printer resolution,
`specifying a mesh resolution of 0.01–0.03 mm and a chord length ≤ 0.016 mm generates an optimal
`STL output file for a given model input file.[59] Specifying higher resolution results in larger files
`without increase in print quality.
`
`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.
`
`Finishing
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`Though the printer-produced resolution is sufficient for many
`applications, greater accuracy can be achieved by printing a
`slightly oversized version of the desired object in standard
`resolution and then removing material using a higher-resolution
`subtractive process.[60]
`
`The layered structure of all additive manufacturing processes
`leads inevitably to a stair-stepping effect on part surfaces which
`are curved or tilted in respect to the building platform. The effects
`strongly depend on the orientation of a part surface inside the
`building process.[61]
`
`3:31 Timelapse of an 80-minute
`video of an object being made out of
`PLA using molten polymer
`deposition
`
`Some printable polymers such as ABS, allow the surface finish to
`be smoothed and improved using chemical vapor processes[62] based on acetone or similar solvents.
`
`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[63] or steel.[64]
`
`Materials
`
`Traditionally, 3D printing focused on polymers for printing, due to
`the ease of manufacturing and handling polymeric materials.
`However, the method has rapidly evolved to not only print various
`polymers[66] but also metals[67][68] and ceramics,[69] making 3D
`printing a versatile option for manufacturing. Layer-by-layer
`fabrication of three-dimensional physical models is a modern
`concept that "stems from the ever-growing CAD industry, more
`specifically the solid modeling side of CAD. Before solid modeling
`was introduced in the late 1980s, three-dimensional models were
`created with wire frames and surfaces."[70] but in all cases the
`layers of materials are controlled by the printer and the material
`properties. The three-dimensional material layer is controlled by deposition rate as set by the printer
`operator and stored in a computer file. The earliest printed patented material was a Hot melt type ink
`for printing patterns using a heated metal alloy. See 1970s history above.
`
`Detail of the Stoofbrug in
`Amsterdam, the world's first 3D-
`printed metal bridge[65]
`
`Charles Hull filed the first patent on August 8, 1984, to use a UV-cured acrylic resin using a UV
`masked light source at UVP Corp to build a simple model. The SLA-1 was the first SL product
`announced by 3D Systems at Autofact Exposition, Detroit, November 1978 in Detroit. The SLA-1 Beta
`shipped in Jan 1988 to Baxter Healthcare, Pratt and Whitney, General Motors and AMP. The first
`production SLA-1 shipped to Precision Castparts in April 1988. The UV resin material changed over
`quickly to an epoxy-based material resin. In both cases, SLA-1 models needed UV oven curing after
`
`https://en.wikipedia.org/wiki/3D_printing
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`being rinsed in a solvent cleaner to remove uncured boundary resin. A Post Cure Apparatus (PCA)
`was sold with all systems. The early resin printers required a blade to move fresh resin over the model
`on each layer. The layer thickness was 0.006 inches and the HeCd Laser model of the SLA-1 was 12
`watts and swept across the surface at 30 in per second. UVP was acquired by 3D Systems in Jan
`1990.[71]
`
`A review in the history shows a number of materials (resins, plastic powder, plastic filament and hot-
`melt plastic ink) were used in the 1980s for patents in the rapid prototyping field. Masked lamp UV-
`cured resin was also introduced by Cubital's Itzchak Pomerantz in the Soldier 5600, Carl Deckard's
`(DTM) laser sintered thermoplastic powders, and adhesive-laser cut paper (LOM) stacked to form
`objects by Michael Feygin before 3D Systems made its first announcement. Scott Crump was also
`working with extruded "melted" plastic filament modeling (FDM) and Drop deposition had been
`patented by William E Masters a week after Charles Hull's patent in 1984, but he had to discover
`Thermoplastic Inkjets introduced by Visual Impact Corporation 3D printer in 1992 using inkjets from
`Howtek, Inc., before he formed BPM to bring out his own 3D printer product in 1994.[71]
`
`Multi-material 3D printing
`
`Efforts to achieve multi-material 3D printing range from
`enhanced FDM-like processes like VoxelJet, to novel voxel-based
`printing technologies like layered assembly.[72]
`
`A drawback of many existing 3D printing technologies is that they
`only allow one material to be printed at a time, limiting many
`potential applications which require the integration of different
`materials in the same object. Multi-material 3D printing solves
`this problem by allowing objects of complex and heterogeneous
`arrangements of materials to be manufactured using a single
`printer. Here, a material must be specified for each voxel (or 3D
`printing pixel element) inside the final object volume.
`
`A multi-material 3DBenchy.
`
`The process can be fraught with complications, however, due to the isolated and monolithic
`algorithms. Some commercial devices have sought to solve these issues, such as building a Spec2Fab
`translator, but the progress is still very limited.[73] Nonetheless, in the medical industry, a concept of
`3D printed pills and vaccines has been presented.[74] With this new concept, multiple medications can
`be combined, which will decrease many risks. With more and more applications of multi-material 3D
`printing, the costs of daily life and high technology development will become inevitably lower.
`
`Metallographic materials of 3D printing is also being researched.[75] By classifying each material,
`CIMP-3D can systematically perform 3D printing with multiple materials.[76]
`
`4D printing
`
`Using 3D printing and multi-material structures in additive manufacturing has allowed for the design
`and creation of what is called 4D printing. 4D printing is an additive manufacturing process in which
`the printed object changes shape with time, temperature, or some other type of stimulation. 4D
`printing allows for the creation of dynamic structures with adjustable shapes, properties or
`functionality. The smart/stimulus responsive materials that are created using 4D printing can be
`
`https://en.wikipedia.org/wiki/3D_printing
`
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`CONTINUOUS COMPOSITES INC. - EX2001
`MarkForged Inc. v. Continuous Composites Inc.
`IPR2022-01218 - Page 10 of 51
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`3D printing - Wikipedia
`6/13/22, 9:34 AM
`activated to create calculated responses such as self-assembly, self-repair, multi-functionality,
`reconfiguration and shape shifting. This allows for customized printing of shape changing and shape-
`memory materials.[77]
`
`4D printing has the potential to find new applications and uses for materials (plastics, composites,
`metals, etc.) and will create new alloys and composites that were not viable before. The versatility of
`this technology and materials can lead to advances in multiple fields of industry, including space,
`commercial and the medical field. The repeatability, precision, and material range for 4D printing
`must increase to allow the process to become more practical throughout these industries.
`
`To become a viable industrial production option, there are a couple of challenges that 4D printing
`must overcome. The challenges of 4D printing include the fact that the microstructures of these
`printed smart materials must be close to or better than