CAD-based automated machinable feature extraction

Feature technology is used to bridge the gap between design and manufacturing, several approaches have been used to support the existing CAD systems. However, most of design features can not be applied to the downstream process directly. We explore an automatic scheme which can extract machinable features from CAD data and use it to determine related process planning. The proposed system is accomplished through three key steps. First, a feature extractor is used to extract and recognize form features of a design part from the CAD database of the IGES format. Based on 2D primitives classification rules of our prior work, all the 3D form features in a part can be recognized. The form features and related parameters are compiled into a form feature adjacency graph (FFAG) with 3D part base, which is used as the output of the feature extractor. Second, a feature transformer is used to change the FFAG into a DSG-like tree. Since the feature type in this tree structure can be treated as a composite of removable volume from the part stock. Therefore it may serve as a good linkage between the CAD and CAM. Finally, a set of machinable features and related constraints are generated using production rules. A loosely correspond machining process, thereafter, may be developed by an automated process planner. A testing part is provided to demonstrate our scheme