Recognition of machining features and feature topologies from NC programs

The machining feature is a high-level product geometric representation and macro description of the product geometry. It is vital to machining operation planning and integration of CAD and CAM systems. In the feature-based operation planning, given a feature, the operator needs its associated machining operation data. Since successful NC programs contain machining know-how of skilled workers associated with the machining features, this paper studies the recognition of machining features in milling from the NC programs through reverse engineering, for reuse of the know-how in operation planning. First, the concepts of the machining element, machining feature and feature topology are presented, and the classification and representation of the features are performed from the machining point of view. Then algorithms for recognizing the machining features and feature topologies by analyzing NC programs are developed based on progressive Z-maps. Finally, a prototype is developed to extract the machining features and their associated operation data, and the machining know-how database is generated accordingly. The recognition of a variety of machining features and topologies, as well as their associated machining operations, is demonstrated through an example part from NIST parts repository. By using the generated machining know-how database, the machining operation planning will be automated by its counterpart system—the machining operation planner.