TWI Frequently asked questions
In the manufacturing arena, productivity is achieved by guiding a product from concept to market quickly and inexpensively. Rapid prototyping, often known as RP, aids this process. It involves automating the fabrication of a prototype part from a three-dimensional (3D) CAD drawing.
The availability of a physical model often conveys more complete information about the product earlier in the development cycle. The turnaround time for a typical rapid prototype can take a few days. Conventional prototyping may take weeks or even months, depending on the method used.
Other terms applied to rapid prototyping technology include, desktop manufacturing, automated fabrication, tool-less manufacturing and free-form fabrication.
Fabrication processes fall into three categories. The first two of these are used in 'conventional' prototyping, whereas the third involves new technologies commonly known as rapid prototyping.
- Subtractive - a block of material is carved out to produce the desired shape e.g. milling, turning, and grinding
- Compressive - forces a semi-solid or liquid material into the desired shape, in which it is then induced to harden or solidify e.g. casting or moulding
- Additive - builds an object by joining particles or layers of raw material
Additive processes can be categorised by the materials involved:
- Photo-polymer systems start with a liquid resin, which is then solidified by discriminating exposure to a specific wavelength of light
- Thermoplastic systems begin with a solid material, which is then melted and fuses upon cooling
- The adhesive systems use a binder to connect the primary construction material
These rapid prototyping systems are capable of creating parts with small internal cavities and complex geometry. This is usually not possible with the subtractive or compressive processes.
For further information contact
Rapid Prototyping - technology overview carried out under TWI exploratory funding
(Industrial Members Report No. 620 - August 1997)
(This report is only available to TWI Industrial Members).
