Feature techniques have played an important role in CAD/CAM integration. These techniques need to be developed for each type of manufacturing process owing to its unique characteristics. Therefore, an approach is proposed in this paper to extract the machining feature of region containing internal sharp points for the process preparation of electrical discharge machining (EDM). The hint feature points are innovatively defined and classified into three types: internal sharp points, cutting-into points and interacting points. Based on this, our approach firstly identifies the faces and the type of the region. Secondly, the interacting region is decomposed into isolated regions through reconstructing the topological structure of the region. Thirdly, the reconstructed faces and original faces are stitched together to form a closed surface, and the CAD models of volumetric features are constructed. Finally, the position and dimension parameters are extracted and saved. The shape and parametric information extracted can be used for subsequent procession preparation, so as to promote the CAD/CAM integration of EDM. 
Feature recognition and volume generation of uncut regions for electrical discharge machining