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"Fabricating items in low-cost printers"

3D printing or additive manufacturing (AM) is any of various processes of making a three- dimensional object from a 3D model or other electronic data source primarily through additive processes in which successive layers of material are laid down under computer control. A 3D printer is a type of industrial robot.

Need a new lens cap? Print it up. That's the way of the future. Instead of fabricating in a factory and shipping the item wherever it's needed, 3D printers are expected to produce everything from architect models to sinks to spare camera parts. "It's already happening at service bureaus," says Jackie Fenn, an analyst at Gartner. "It hasn't happened at a physical shop like Kinko's, but I think it's very possible."

History

Early AM equipment and materials were developed in the 1980s. They were expensive and most required special handling.The names 3D printing and additive manufacturing did not yet have currency as umbrella terms for the field; each AM technology usually went by its own name. In 1984, Chuck Hull of 3D Systems Corp, invented a process known asstereolithography employing UV lasers to cure photopolymers. Hull also developed the STL file format widely accepted by 3D printing software, as well as the digital slicing and infill strategies common to many processes today. Also during the 1980s, the metal-sintering forms of AM were being developed (such as selective laser sintering and direct metal laser sintering), although they were not yet called 3D printing or AM at the time.

In 1990, the plastic extrusion technology most widely associated with the term "3D printing" was commercialized by Stratasysunder the name fused deposition modeling (FDM). In 1995, Z Corporation commercialized an MIT-developed additive process under the trademark 3D printing (3DP), referring to a proprietary process inkjet deposition of liquid binder on powder. The term was later applied more loosely to distinct but related inkjet material deposition or drop-on-droptechnologies.

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 on-going RepRap Project and associated open-source software initiatives "The RepRap's Heritage. In distributed manufacturing, one study has found 3D printing could become a mass market product enabling consumers to save money associated with purchasing common household objects.

General Principles

3D printable models

3D printable models may be created with a computer aided design package or via 3D scanner. The manual modelling process of preparing geometric data for 3D computer graphics is similar to plastic arts such as sculpting. 3D scanning is a process of analysing and collecting digital data on the shape and appearance of a real object. Based on this data, three-dimensional models of the scanned object can then be produced.

Both manual and automatic creation of 3D printable models is difficult for average consumers. This is why several 3D printing marketplaces have emerged over the last years. Among the most popular are Shapeways,Thingiverse, MyMiniFactory and Threeding 

Printing

To perform a print, the machine reads the design from 3D printable file (STL File) and lays down successive layers of liquid, powder, paper or sheet material to build the model from a series of cross sections. These layers, which correspond to the virtual cross sections from the CAD model, are joined or automatically fused to create the final shape. The primary advantage of this technique is its ability to create almost any shape or geometric feature.

Printer resolution describes layer thickness and X-Y resolution in dpi (dots per inch), or micrometres. Typical layer thickness is around 100 µm (250 DPI), although some machines such as theObjet Connex series and 3D Systems' ProJet series can print layers as thin as 16 µm (1,600 DPI). 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 with a higher-resolution subtractive process can achieve greater precision. As with the LUMEX Avance-25  and other machines slated for IMTS 2014.

Some additive manufacturing techniques are capable of using multiple materials in the course of constructing parts. Some are able to print in multiple colours and color combinations simultaneously. Some also utilise supports when building. Supports are removable or dissolvable upon completion of the print, and are used to support overhanging features during construction.

Current Technologies

3D printing is an additive technology in which objects are built up in a great many very thin layers. The first commercial 3D printer was based on a technique called stereolithography. This was invented by Charles Hull in 1984. Stereolithographic 3D printers (known as SLAs orstereolithography apparatus) position a perforated platform just below the surface of a vat of liquid photopolymer.Stereolithographic printers remain one of the most accurate types of hardware for fabricating 3D output, with a minimum build layer thickness of only 0.06mm (0.0025 of an inch).

Another 3D printing technology based on the selective solidification of a tank of liquid -- or 'vat polymerization' -- is DLP projection. This uses a projector to solidify object layers one complete cross-section at a time, rather than using a laser to trace them out.

A final 3D printing technology that creates objects by using a light source to solidify a liquid photopolymer is known generically as 'material jetting', or commercially as 'polyjet matrix'. This was pioneered by a company called Object.

Commercial 3D Printers and Online Services

A wide range of commercial 3D printers for industrial application are now available from a range of manufactuers, the two largest of whom are 3D Systems (which works with most technologies and is rapidly acquiring many smaller manufacturers) and Stratasys (which offers FDM and polyjet matrix harware, as well as special 'drop on demand' wax 3D printers for dental work). Both of these companies had a market capitalization at the end of 2012 of over $3 billion.

Other large 3D printer manufactuers that are publically traded are Archam (which produces electron beam melting (EMB) machines), the aforementioned ExOne with their metal and sand binder jetting 3D printers, and Organovo, who specialize in bioprinting.

Other large but private 3D printer manufacturers of note include EnvisionTEC (who specialize in DLP projection hardware but also make a 'bioplotter' for tissue engineering), EOS (who make selective laser sintering devices for producing objects in metals or sand), Voxeljet (who make really large printers for binder jetting in sand or plastic powders), SLM Solutions (who specialize in selective laser melting), and Optomec (who produce directed energy deposition printers using their own 'laser engineered net shaping' (LENS) technology). You can find information on these and other industrial 3D printing manufactuers in my 3D Printing Directory.