A MODEL FOR INTERFACING GEOMETRIC MODELING DATA WITH RAPID PROTOTYPING SYSTEMS

Rapid prototyping processes are becoming viable techniques for integrating product design and manufacturing cycles. These processes have the potential to achieve maximum designer-user interaction harmonizing the initial specifications with final operational requirements of a product. Rapid prototyping processes often begin with the creation of a model using a CAD modeler. This model is then sliced to generate data about successive layers which are then constructed one layer at a time by various processes depending on the rapid prototyping method. Currently, slicing is performed on a tessellation of the CAD model which is an approximation of the model itself. There are few problems that are at the heart of this technique, including the numerical inaccuracies resulting from round-off errors due to manipulating non-integer data, as well as the dependence on proprietary algorithms for generating the slice data. These numerical problems are reflected in the quality of the surface finish of the final product. This paper presents a technique for interfacing the CAD model with the rapid prototyping process which bypasses the surface modeling by tessellation and the approximations to the actual geometry that are inherent in this process and in the subsequent slicing of the model. The technique presented is based on slicing the model directly using its complete geometric representation. This technique represents an advancement over the currently used slicing methods and provides the means for generating smoother surface finish.