Extracting process planning information from various wire frame and feature based CAD systems

In recent years, features have been identified by the engineering community as meaningful abstractions with which humans can reason about products and processes. From the designer's point of view, features are functional primitives, which serve as the basis for sufficient product representation, improving the quality of design and the link to life cycle activities, such as process planning and manufacturing. Up to now, virtually no commercial wire frame CAD system gives the user the possibility to design with features. All objects in a drawing are loose CAD entities (points, lines, arcs,…) that can not be recognised as features. Feature based CAD systems mostly offer the user a fixed feature catalogue to design with. In many cases this feature catalogue is too rigid (a fixed set of feature types with fixed parameters) and does not correspond to the features that are used in a company for other feature based applications (e.g. process planning, NC programming,…). This paper describes a method for defining and extracting user definable manufacturing feature information from several wire frame and feature based CAD systems. This method is applied in a software module that interfaces CAD systems and a feature based process planning system [18,19]. The development of this module, called the CAD Process Planning Interface (CAD PPI), was carried out in the framework of the Esprit project 6805 COMPLAN [22].