Rapid Prototyping

New techniques in computer-aided manufacturing enable prototype components to be manufactured to very close tolerances from three-dimensional computer-aided design (CAD) solid modelling images. This has implications not only for the design of building components but also for the manufacture of architectural models.

The systems are based on the successive build-up of very thin layers of solid material to the exact pattern of layered CAD sections. Various lay-up systems have been developed for the deposition of plastic layers. These range from a fine nozzle, to using laser technology to accurately polymerise viscous resin in very thin layers and the use of adhesive-backed paper cut by laser to the required section shapes. Each system produces a highly accurate three-dimensional solid over a period of several hours depending upon the product size. Where any part of the build-up of the solid object needs support during manufacture, the systems automatically produce additional material in a weak form. This can be broken away easily after the whole object is complete, and in the case of laser/resin production finally cured. In all these manufacturing processes the build-up layers are extremely thin, so smooth and accurate surfaces are achieved.

The reverse of this process allows prototype complex shape components or small-scale architectural models to be turned into accurate three-dimensional CAD files, using a delicate probe mechanism which senses all over the object's surfaces. This allows the designer to generate CAD files for highly complex three-dimensional forms which would be virtually impossible to draw directly into a CAD system.

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