Rapid prototyping (RP) uses automated manufacturing techniques to quickly fabricate objects. These techniques, which create three-dimensional (3-D) models directly from computer designs, are generally faster and less expensive than traditional methods such as machining. The ability to create a prototype model in a relatively short amount of time—a few hours or days—has great benefits for product design and development. For example, rapid prototyping allows for feedback early in the product-development process, providing an opportunity for changes and corrections to be made. This can decrease both development time and mistakes. In addition, being able to reference a tangible model can improve communication among the people involved in the development process—colleagues and customers alike.

Rapid prototyping techniques are based on a principle called additive manufacturing, in which an object is formed by joining materials together. (By contrast, subtractive manufacturing removes material from a larger block to make products.) Rapid prototyping uses a computer program, such as computer-aided design (CAD), to visualize the object as a collection of cross sections. A machine then takes the data from the virtual model and builds a 3-D model by fusing together layers of material, such as plastic, paper, metal, clay, or wax. An automated fabrication process forms the shape of each cross section, layer by layer, until the object is complete.

There are many types of rapid technologies. Some common methods are selective laser sintering, which uses a laser to fuse powdered material to form each layer; 3-D printing, which builds objects using two printer heads—one that spits out powder and another that spits out bonding agent; fused deposition modeling, which deposits molten polymers; stereolithography, which uses photosensitive polymers that solidify when exposed to ultraviolet light; and laminated object manufacturing, which bonds together sheets of paper that have been laminated with heat-activated glue.

Rapid prototyping technologies are useful in product design and development, but the techniques are now finding applications in other fields, such as in the medical and dental industry, architecture, animation, jewelry design, and fashion. Objects created by RP techniques can be used as a final product or to help create molds and casts. It can also be used for testing purposes, such as placing the product in a wind tunnel to measure how aerodynamic it is. Because of its many uses beyond prototyping, RP is also referred to as solid freeform fabrication, computer-automated manufacturing, or layered manufacturing.

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