A recent story in the San Jose Mercury News, entitled "Emerging 3D printers prove useful to users of all ages," reports on the use of 3D printers by public library patrons in Silicon Valley. The story provides this succinct description of the 3D printing process:
A 3D printer reads digital files and then creates objects by laying down one thin layer of different materials--in most cases, melted plastic--layer by layer on top of another until the object is complete. Different printers can use a variety of materials ranging from paper to metal. Objects are designed with software on an X, Y and Z axis.
A slightly more expansive summary description is given on the TechCrunch website:
3D printing, also known as additive manufacturing, includes any of various processes of making a three-dimensional object from a 3D model or other electronic data source primarily through additive processes.
In these processes, successive layers of material (liquid, powder, paper, or sheet material) are laid down under computer control. It requires use of a 3D printer, which is a type of industrial robot. 3D printable models can be created with a computer aided design package or via a 3D scanner.
The anticipated impact of 3D printing is enormous. Part of that impact stems from reduction in the time required for product development, reduction in tooling costs, and reduced waste. Part of the impact also stems from the vast range of what can be produced using 3D printing. Consider, for example, housing, clothing, food (even ice cream!).
As illustrated above, 3D printing can be approached from two directions; its literature is also developing along these two axes. The first direction is the basic technology of 3D printers. As noted in the TechCrunch summary, 3D printing is an additive manufacturing process. In the DDC, additive manufacturing has been provided for in an expansion at 621.988 Additive manufacturing equipment, with three-dimensional printers in its class-here note. For example, 3D printing with Autodesk 123 : create and print 3D objects with 123D, Autocad, and Inventor is classed in 621.988.
The second direction is the application of 3D printing in the manufacture of various products. We considered options ranging from providing a Table 1 notation for three-dimensional printing to not reflecting the additive manufacturing process in the manufacture of a specific product in any way. (After all, 3D printing is unlikely to be considered special over the long haul.) We have opted for a middle-of-the-road solution, given in a scatter class-elsewhere note at 621.988: "Class additive manufacturing applications in a subject with the subject, plus notation T1--028 [Auxiliary techniques and procedures; apparatus, equipment, materials] from Table 1, e.g., three-dimensional printing applied to creation of costume jewelry as artistic work 745.5942028." In the future we expect to see works like The development of colour 3D food printing system classed in 664.0028 (built with 664 Food technology, plus notation T1—028; standard subdivisions under 664 are on two zeros), and Printable prosthetic hand classed at 681.761 (Manufacture of ) Medical and health equipment (note: since "prosthetic devices" are in the including note, they do not approximate the whole of 681.761; standard subdivision T1—028 therefore cannot be added).