Prototyping is the most common name given to a host of related technologies that are used to fabricate physical objects directly from CAD data sources. These methods are unique in that they add and bond materials in layers to form objects. Such systems are also known by the general names freeform fabrication (FFF), solid freeform fabrication (SFF) and layered manufacturing. Today’s additive technologies offer advantages in many applications compared to classical subtractive fabrication methods such as milling or turning: Objects can be formed with any geometric complexity or intricacy without the need for elaborate machine setup or final assembly; Prototyping systems reduce the construction of complex objects to a manageable, straightforward, and relatively fast process.
This has resulted in their wide use by engineers as a way to reduce time to market in manufacturing, to better understand and communicate product designs, and to make rapid tooling to manufacture those products. Surgeons, architects, artists and individuals from many other disciplines also routinely use the technology.
Prototyping isn’t a solution to every part fabrication problem. After all, CNC technology is economical, widely understood and available, offers wide material selection and excellent accuracy. However, if the requirement involves producing a part or object of even moderately complex geometry, and doing so quickly – Prototyping has the advantage. It’s very easy to look at extreme cases and make a determination of which technology route to pursue, CNC or RP. For many other less extreme cases the selection crossover line is hazy, moves all the time, and depends on a number of variably-weighted, case-dependent factors. While the accuracy of prototyping isn’t generally as good as CNC, it’s adequate today for a wide range of exacting applications.