Copyright (version 0.1) (C) 1996 Hugh Jack, ABSOLUTELY NO WARRANTY
If we look at recent rapid prototyping research we will see its ability to mesmerize, but it often leaves us aksing what it can be used for. This question is quite valid, and can be answered naively by saying - when we have very small batches of parts to be made that are difficult to machine, we can use rapid prototyping to generate complete geometris fast. In fact the rapid prototyping are best considered to be fixtureless manufacturing devices, thus allowing undercuts, and recessed features that could not be cut easily using NC tools. Even more important, we are able to produce complex tooling using these models. But, to date one of the significant criticisms of this industry is the outrageuous cost of these machines. Other less significant criticisms are material choices, and process limitations (eg. volume, accuracy, post processing).
Research has been conducted into alternative processes, and a method using traditional NC milling machines with common materials, allows very low cost, and easy to perform rapid prototyping processes. In effect a part is built up using layers of wax, and a thermoset polymer. The wax (we have used wax purchased at a hobby store) is poured in thick layers, and pockets are cut using NC milling machines. These pockets are then filled with a thermoset polymer (the most available example is autobody filler, aka Bondo) that hardens to take the shape of the part. Many layers are built up using this process until an entire part is encased in a wax block. The wax is melted and the part removed. This process has been the subject of a recent patent application.
last revised: October 7th, 1996