3D Printing: Make anything you want

Information from Wikipedia

What if you can print any thing you want?

The term 3D printing covers a variety of processes in which material is joined or solidified under computer control to create a three-dimensional object,[1] with material being added together (such as liquid molecules or powder grains being fused together), typically layer by layer. In the 1990s, 3D printing techniques were considered suitable only for the production of functional or aesthetical prototypes and a more appropriate term was rapid prototyping. Today, the precision, repeatability and material range 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. One of the key advantages of 3D printing is the ability to produce very complex shapes or geometries, and a prerequisite for producing any 3D printed part is a digital 3D model or a CAD file.

The most commonly used 3D Printing process is a material extrusion technique called fused deposition modeling (FDM).[2] Metal Powder bed fusion has been gaining prominence lately during the immense applications of metal parts in the 3D printing industry. In 3D Printing, a three-dimensional object is built from a computer-aided design (CAD) model, usually by successively adding material layer by layer, unlike the conventional machining process, where material is removed from a stock item, or the casting and forging processes which date to antiquity.[3][4]

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 term is being used in popular vernacular to encompass a wider variety of additive manufacturing techniques. United States and global technical standards use the official term additive manufacturing for this broader sense.

Terminology
The umbrella term additive manufacturing (AM) gained popularity in the 2000s,[5] 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 theme. 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, ink-jet, or stereo lithography enthusiasts.

By 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.[6] 3D printing and additive manufacturing reflect that the technologies share the theme of material addition or 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[7] 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.[7]

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
1981 : Early additive manufacturing equipment and materials were developed in the 1980s.[8] In 1981, 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.[9][10]

1984 : On 16 July 1984, Alain Le Méhauté, Olivier de Witte, and Jean Claude André filed their patent for the stereolithography process.[11] The application of the French inventors was abandoned by the French General Electric Company (now Alcatel-Alsthom) and CILAS (The Laser Consortium).[12] The claimed reason was “for lack of business perspective”.[13]

Three weeks later in 1984, Chuck Hull of 3D Systems Corporation[14] filed his own patent for a stereolithography fabrication system, 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,”.[15][16] Hull’s contribution was the STL (Stereolithography) file format and the digital slicing and infill strategies common to many processes today.

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.

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 we now call 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 mid-1990s, new techniques for material deposition were developed at Stanford and Carnegie Mellon University, including microcasting[17] and sprayed materials.[18] Sacrificial and support materials had also become more common, enabling new object geometries.[19]

1993 : The term 3D printing originally referred to a powder bed process employing standard and custom inkjet print heads, developed at MIT in 1993 and commercialized by Soligen Technologies, Extrude Hone Corporation, and Z Corporation.

The year 1993 also saw the start of a company called Solidscape, introducing a high-precision polymer jet fabrication system with soluble support structures, (categorized as a “dot-on-dot” technique).

1995: In 1995 the Fraunhofer Institute developed the selective laser melting process.

2009: Fused Deposition Modeling (FDM) printing process patents expired in 2009.[20]

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[21] and large nuts[22] 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.

As technology matured, several authors had begun to speculate that 3D printing could aid in sustainable development in the developing world.[23][24]

2012: Filabot develops a system for closing the loop[25] with plastic and allows for any FDM or FFF 3D printer to be able to print with a wider range of plastics.

2014: Georgia Institute of Technology Dr. Benjamin S. Cook, and Dr. 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 40GHz.[26]

General principles
Modeling
 
CAD model used for 3D printing
 
3D models can be generated from 2D pictures taken at a 3D photo booth.
Main article: 3D 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 reduced errors and can be corrected before printing, allowing verification in the design of the object before it is printed.[27] 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 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.[28]

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,[29][30] of the following types:

holes;
faces normals;
self-intersections;
noise shells;
manifold errors.[31]
A step in the STL generation known as “repair” fixes such problems in the original model.[32][33] Generally STLs that have been produced from a model obtained through 3D scanning often have more of these errors.[34] This is due to how 3D scanning works-as it is often by point to point acquisition, 3D reconstruction will include errors in most cases.[35]

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).[36] 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).[37] 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.[citation needed] For that printer resolution, specifying a mesh resolution of 0.01–0.03 mm and a chord length ≤ 0.016 mm generate an optimal STL output file for a given model input file.[38] Specifying higher resolution results in larger files without increase in print quality.

Play media
 
3:31 Timelapse of an 80 minute video of an object being made out of PLA using molten polymer deposition
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.[39]

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.[40]

Finishing
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.[41]

The layered structure of all Additive Manufacturing processes leads inevitably to a strain-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.[42]

Some printable polymers such as ABS, allow the surface finish to be smoothed and improved using chemical vapor processes[43] 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[44] or steel.[45]

Multi-material printing
Multi-material printing allows objects to be composed of complex and heterogeneous arrangements of materials. It requires a material being directly specified for each voxel inside the object volume. The process is fraught with difficulties, due to the isolated and monolithic algorithms. There are many different ways to solve these problems, such as building a Spec2Fab translator.[46] Or use microstructures to Control Elasticity in 3D Printing.[47] There is also a solution about how to print a Multi-material 3d painting :Deep Multispectral Painting Reproduction via Multi-Layer, Custom-Ink Printing.[48]

Multi-material 3D printing is a fundamental element for development of future technology.[49] It has been already applied to variable industries. Other than common applications in small manufacturing industries, to produce toys, shoes, furniture, phone cases, instruments or even artworks.[50] With the BAAM (Big Area Additive Manufacturing) machine,[51] large products such as 3D printed houses or cars are quite feasible. It has also been widely used in high-tech industries. Researchers are devoting to producing high-temperature tools with BAAM for aerospace applications.

In medical industry, a concept of 3D printed pills and vaccines has been recently brought up.[52] With this new concept, multiple medications are capable of being united together, which accordingly 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 irreversibly lower.

Metallographic materials of 3D printing is also being researched.[53] By classifying each material, CIMP-3D can systematically perform 3D printing with multi materials.[54]

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