Rapid Prototyping Introduction
Prototyping is a process of building pre-production models of a product to test various aspects of its design. Usually it is slow and expensive. Rapid Prototyping (RP) techniques are methods that allow to quickly produce physical prototypes with the important benefit to reduce the Time To Market. By use of these techniques, prototypes can be built needing skill of individual craftsmen for no more than just the finishing the part. Furthermore, the resulting design cost will be decreased considerably.
Within a rapid prototyping process, the object is firstly designed on a computer screen and then created based on the computer data. This eliminates inevitable errors which usually appear when a model-maker interprets a set of drawings. An essential prerequisite is the computer representation: it is usually a 3D geometrical modelling system like a CAD system, a 3D scanner, computer tomography, etc. Its precision is a key parameter controlling the tolerances of the future model (the different techniques allow an average accuracy of approx. 0,1 mm).
Others basic principles of RP are the need for specific materials such as fluids, powders, wire or laminates as well as the need for sophisticated equipment employing different physical principles such as laser, sintering, etc. Though there are no restrictions concerning complexity and geometrical features, the physical objects are limited in their size. An advantage is the fact that the same data used for the prototype creation can be used to go directly from prototype to production, eliminating further sources of human errors.
An important difference between RP and traditional techniques is the fact that most of these new techniques build parts by adding material (e.g. layer by layer) instead of removing it.
Several RP techniques are available. The first commercial process, StereoLithography (SL), was brought on the market in 1987. Nowadays, more than 30 different processes (not all commercialised) with high accuracy and a large choice of materials exist. These processes are classified in different ways: by materials used, by energy used, by lighting of photopolymers, or by typical application range.
The most successfully developed techniques are: