Algorithms for sorting and recognizing of undercut features in plastic products

Abstract

The automatic recognition of features in injection molded parts and assemblies are a crucial step in design to improve efficiency and effectiveness during the development and manufacturing stages. . When an internal undercut is present in the ejecting direction the finished plastic product cannot be directly ejected from the mold. Algorithms using the geometry of the undercut and the molded product are developed to avoid interference between the mould and the molded product when the product is ejected from its mould. The CAD models are developed using both the boundary representation as well as the CSG approach. This paper presents the development of computer algorithms in Java for sorting and recognizing undercut and mold features. The STEP AP 203 translator is used to communicate with various CAD systems. The proposed algorithm takes multiple feature models of plastic products as input and sorts the features using the Radix sort algorithm and then recognizes the features of the undercuts and the molds. Through the volumetric decomposition and the sorting algorithm the proposed approach can automatically recognize undercut features and efficiently calculate the undercut locations and dimensions using the feature parameters.