Prototyping From The Virtual To The Physical World

Virtual prototyping is becoming a cost-effective method used in testing new products and systems. It is an integral part of current rapid prototyping methods wherein virtual designs created from computer aided design (CAD) or animation modeling software are used and then transformed into cross sections in a still virtual environment.

A special machine is then used to create each virtual cross section in then takes physical form layer after layer until an identical prototype model is created. The whole process enables the virtual model become a physical model with corresponding identical features.

In the additive fabrication of virtual prototypes, the rapid prototyping (RP) machine reads the data from a CAD drawing, and forms successive layers of liquid or powdered material according to the virtual data received. It slowly builds up a physical model from a series of cross sections.

These different layers, which match up to the virtual cross sections created from the CAD model, are then glued or fused together to create the final three dimensional prototype model.

All the rapid prototyping technologies in current use have many things in common. All make use of additive processes. Rapid prototyping makes use of additive construction as the means of creating solid prototype objects which has the distinct advantage of creating almost any shape or form that even the best machining and tooling methods may not be able to achieve. During the ensuing development, virtual prototyping goes through a number of stages that eventually turns designs into fully testable three dimensional models.

All the rapid prototyping machines being used slowly form the three dimensional models by putting together thin, two-dimensional layers one at a time. The three dimensional manifestation of the virtual design is formed from the bottom up. Models are formed on an elevator-like platform from virtual CAD designs. The platform is lowered a layer-height at a time once a layer is completed. The thinner the layer, the smoother the finish will be on the completed prototype model. Once the model is completely formed, it may be sanded, plated or painted, depending on material used.

Rapid prototyping technologies can either be a "dry" or a "wet" process. Most machines create prototype models by solidifying some sort of loose powder, liquid, or semi-liquid material. A machine may be able to cut through adhesive-coated sheets of prototype fabrication material. The dry powdered materials can either be some sort of polymer, powdered metal, or wax. Some machines may even be able to use starch as the building material for forming the prototype model.

Some of the powders used may also require a binder. The liquid materials mainly used are usually photosensitive polymers that solidify when exposed to either a laser or ultraviolet (UV) light. Wet rapid prototyping methods generally require a curing phase.