Additive manufacturing or 3D printing is a manufacturing process used to make three-dimensional solid objects from a three-dimensional digital design file. The actual manufacture, is achieved by using an additive process, meaning that successive layers of material are laid down to form the desired shapes. Where traditional machining techniques are based mostly on the removal of material by methods such as cutting or drilling (subtractive processes), 3D printing is based upon adding materials (additive process).
Normally, a model would be designed using tools such as CAD (computer aided design) software and then that model would be created using the additive process. The first working 3D printer was created in 1984 by Chuck Hull of 3D Systems Corporation and since that moment there has been a large growth in the sales of these machines, and subsequently their price has dropped substantially.
The technology is currently used for prototyping and distributed manufacturing with applications in various industries such as architecture, construction, industrial design, automotive manufacture, aerospace, military, engineering, civil engineering, dental and medical industries, biotechnology, fashion, footwear, jewelry, eye-wear, education, food, and many other industry fields.
However, the applicability thereof leaves many questions with regard to the field that the technology is employed in. Often one of the bigger questions related to such products is about the product’s actual strength. Subtractive manufacturing e.g. machining a high speed fighter jet’s wing skin from a solid block of material, is still considered to be the only option when high temperatures, pressures, stresses and strains are involved.
A myriad of machines is currently available, from the simple “home designer” model to sophisticated systems such as those recently used by NASA for ISS spares and Rocket Engine parts. Whether these machines or processes will replace in part or in whole the methods used today will depend entirely on the ability of these machines to replicate current standards or to exceed them.
Wikipedia offers a very complete article on the subject: All about 3D Printing