A hybrid method for recognition of undercut features from moulded parts

Products manufactured by moulding processes, such as injection moulding or die casting, are called moulded parts. This paper describes a hybrid method to recognise undercut features from moulded parts with planar, quadric and free-from surfaces. The hybrid method takes advantage of graph-based and h int-based approaches. Various undercut features, including interacting unde rcut features, are defined by extended attributed face-edge graphs (EAFEG). Unlike conventional graph-based methods, which recognise features by graph matching, the new approach recognises the undercut features by searching t he cut-sets of subgraphs. Face properties and parting lines are used as hin ts to guide the search of cut-sets. To recognise undercut features from par ts with free-form surfaces, a convex-hull algorithm is used to determine th e face properties (positive, negative and horizontal). The case study shows that the proposed method can recognise various undercut features successfu lly. (C) 2001 Elsevier Science Ltd. All rights reserved.