Object-oriented analysis and design of a manufacturing feature representation

This paper describes the modelling of a manufacturing feature by taking geometry and tolerancing into account. This modelling is based on a conceptual definition of the manufacturing feature based on interactions between the primary features extracted from the Computer Aided Design (CAD) model: form features, precision features and technological features. The phase of specification was carried out with the use of the Object-Oriented System Analysis (OOSA) method. The data representation and processing are presented through the description of the eight models of the OOSA method. A classification of the manufacturing features is proposed according to the possible interactions between the primary features. A Topological and Technological Interaction (TTI) graph shows the level of complexity of the interconnection of the features. The extracting mechanism of primary features from the CAD system is described. The manufacturing features, automatically extracted from the CAD model defined in a CATIA environment, are manipulated by a Generative Computer Aided Process Planning (GCAPP) system to generate the machining operation sequences automatically. The manufacturing feature representation proposed is of extreme interest thanks to the geometry but especially to the tolerancing which is too often ignored.