Rapid prototyping is a family of additive production processes used to assemble prototype models. These processes are known as additive methods, as material is added to the model during construction rather than cut away from a solid block. Members of this family in general use include selective laser sintering (SLS), stereolithography (SLA), and three-dimensional (3D) printing (3DP). Laminated object manufacturing (LOM), fused deposition modeling (FDM), and electron beam melting (EBM) are also among the more common rapid prototyping processes. All of these processes are automated and executed by machinery that is controlled by computers reading data from computer aided design (CAD) models of the prototype.
Prototyping is the practice of building models of new products or revisions of existing products prior to final approval and full-scale production. This process allows designers and developers to assess their designs, identify faults or omissions, and demonstrate the concept to any interested parties. Understandably prototyping is a critical part of any design process, often returning considerable time and budget savings. Rapid prototyping is one of the more popular methods used to construct prototype models. The process is an additive one, meaning that the machines used add material to the model as the building progresses in contrast to subtractive processes which cut away material from a blank block.
There are several different rapid prototyping techniques in general use that use metals, thermoplastics, and photopolymers to gradually build the prototype, layer by layer, from scratch. One of the more popular of these is selective laser sintering (SLS), which utilizes a high-power carbon dioxide laser to fuse plastic, ceramic, or glass powder into the finished model. The laser runs in a pattern that exactly mimics a CAD model stored in the machine's computer controller, changing the powder into a solid body as it goes. Direct metal laser sintering (DMLS) is a similar process that uses metal powders.
Another commonly used rapid prototyping process that works in a similar fashion is stereolithography. This process utilizes an ultraviolet (UV) laser that moves through a tank of photopolymer resin formulated to cure, or harden, when exposed to UV light. As the laser traces the shape stored in the CAD file, the resin solidifies, progressively building up the prototype model. One of the most significant recent developments in rapid prototyping is the three-dimensional (3D) printing process, which involves a inkjet-type printer that lays successive layers of powdered resin and binders down to progressively build the desired shape. There are also several other processes used in rapid prototyping which, although featuring subtle process differences, all share the same progressive, additive model building technique.