An investigation of parting direction based on dexel model and fuzzy decision making

Abstract

This paper presents a method for automatic mould parting direction selection in computer-aided design of moulds and dies. When given a three-dimensional CAD model, the minimum volume bounding box of the model is found first. Three pairs of possible parting directions are defined based on the bounding box surface normal vectors. They are in the length direction, the width direction and the height direction of the bounding box. Now, a dexel model is constructed along each parting direction. Parting lines corresponding to the three possible parting directions are estimated using a slice method. Finally, criteria such as undercut, draw, projected area and flatness in all parting directions are quantified using the dexel model of the part. A designer's preferences, coded as fuzzy weighting factors, are set-up for the evaluation of the most promising parting direction. Uncertainty that is assumed to be inherent in the assessments of the ratings and weights is accounted for by the proposed fuzzy heuristic.