Incomplete mesh offset for NC machining

In this paper, the incomplete triangular mesh including reversed faces and gaps between boundary edges is directly offset for NC machining. For three-axis machining, vertical faces are deleted and the face normal vectors directing the lower part of model are changed to upward. The complete mesh is offset by the multiple normal vectors of a vertex, and boundary edges and boundary vertices are offset by the virtual multiple normal vectors of a boundary vertex. For five-axis machining, mesh is offset to both directions by the reversed multiple normal vectors. Using this method, the CL surface is directly obtained from an incomplete triangular mesh. To show that the proposed offset method is effective for NC machining, the tool path generated from the CL surface is verified by simulation and real NC machining.