A MODEL FOR INTERFACING GEOMETRIC MODELING DATA WITH RAPID PROTOTYPING SYSTEMS

Rapid prototyping processes are becoming viable techniques for integra ting product design and manufacturing cycles. These processes have the potential to achieve maximum designer-user interaction harmonizing th e initial specifications with final operational requirements of a prod uct. Rapid prototyping processes often begin with the creation of a mo del using a CAD modeler. This model is then sliced to generate data ab out successive layers which are then constructed one layer at a time b y various processes depending on the rapid prototyping method. Current ly, slicing is performed on a tessellation of the CAD model which is a n approximation of the model itself. There are few problems that are a t the heart of this technique, including the numerical inaccuracies re sulting from round-off errors due to manipulating non-integer data, as well as the dependence on proprietary algorithms for generating the s lice data. These numerical problems are reflected in the quality of th e surface finish of the final product. This paper presents a technique for interfacing the CAD model with the rapid prototyping process whic h bypasses the surface modeling by tessellation and the approximations to the actual geometry that are inherent in this process and in the s ubsequent slicing of the model. The technique presented is based on sl icing the model directly using its complete geometric representation. This technique represents an advancement over the currently used slici ng methods and provides the means for generating smoother surface fini sh.