The normal curvature approach model is a new milling method of machining complex freeform surfaces presented in this paper based on 5-axis CNC machines. For this milling model, its key is to optimize the CL-data of whirlwind milling tool so that the symmetric rotational surface, which is generated while the whirlwind milling tool rotates, can closely approach to the surface being machined. Then, this method evidently raises the material removal rate at the point of contact and efficiently improves the machining productivity.
In the paper, a new-typed whirlwind milling tool with standard-sized circular cutters is introduced, and a special 5-axis CNC horizontal bed-typed milling machine is used in manufacturing the freeform surfaces. The tool path generation algorithm about normal curvature approach milling method and its typical examples are analyzed in detail.