ABSTRACT
In this paper a framework based on the concept of functional dimensioning features is presented. It is aimed at supporting a methodological approach to explicit modeling with a focus on issues related to its use in MCAD education and practice. The proposed framework is based on the assumptions that shape, dimensions, and required manufacturing precision of a mechanical component are designed to fulfill specific functionalities. Principle formation and development regarding geometric entities and associated functional meaning are approached with an orientation on the concepts and definitions introduced by the GPS system of standards. Application of the GPS standards requires that dimensions and tolerances of the functional elements are specified within the nominal representation of a part or component. The traditional method of representing such information is a 2D technical drawing. However, explicit modeling provides new perspectives and opportunities for approaching 3D modeling, since it allows the addition of geometrical constraints and driving dimensions directly on the 3D model. In this context, the concept of functional dimensioning features is introduced, aimed at providing an integrative correspondence between concepts as specified by the GPS standards and the operative framework as provided by explicit modeling.