Prototyping is the stage in product development prior to manufacturing in which test parts are created to judge a design's form, fit and function. This way if there are problems with the design, engineers can make the necessary changes prior to manufacturing. Rapid prototyping is the construction of physical objects using additive manufacturing. That is, parts are built up, layer by layer. As technology has advanced, so have rapid prototyping technologies. Test parts can now be made in hours and in a variety of materials.
Three-dimensional printing is the process of additively building 3-D objects layer by layer. Three-dimensional printers work quickly and accurately and are able to build test parts in various plastics. They work similarly to ink printers, in that a printing head lays down the material. As of 2011, manufacturers are working to make 3D printers more affordable and compact, so businesses can purchase them for their rapid prototyping needs. For example, 3D printer developer/manufacturer Objet Geometries offers desktop models, the Objet24 and Objet30, that cost less than $20,000 at the time of publication.
Laser sintering is a rapid prototyping process that uses a high-power laser to fuse material into a three-dimensional part. These systems work with a powder bed, which is where powdered particles of the material are located at the bottom of the system's build area. The laser then cross-scans sections of the powder bed to additively build the part. Laser sintering machines can build parts in plastics, ceramics, glass and even metal. Laser sintering can be used for prototype and end use parts.
Direct Metal Deposition
Rapid prototyping isn't just limited to technology that builds plastic parts. Direct metal deposition technology is an additive process that creates fully dense metal parts. The technology was developed by Precision Optical Manufacturing Group. It works by streaming a beam of powdered metal from a nozzle onto a build surface. It's able to create accurate metal parts, which share the same mechanical properties of traditional metals, in hours. Direct metal deposition is especially useful for prototyping parts that must perform under extreme conditions, such as in aerospace, military and automotive applications.
Electron Beam Melting
Similar to direct metal deposition, electron beam melting is capable of additively building fully dense metal parts. However with electron beam melting, the parts are melted by a powerful electron beam. Parts are built in a vacuum at high temperatures and parts are comparable to those that are cast. Final parts are comparable to wrought metal parts. Accuracy is exact, as each layer is melted to the geometry defined by the computer aided design model. Electron beam melting is able to build parts in materials ranging from stainless steel to titanium.