Abstract:To avoid low machining efficiency, unstable machining process and poor quality during the numerical control (NC) machining of freefrom surfaces, there are a lot of small straight line segment to approach curves of tool paths, combining with linear and spline, a hybrid tool paths generation algorithm including segment points identification with multicriteria method (MCM) and adaptive least square fitting based on dominant points method (DOM) is proposed. Segment points contained end points of long lines and the corner points, the MCM extracted the longline one by comparing the distance between the adjacent cutter locations (CL), and then obtained the corner one by Kcosine and threepointcircle method gradually. Eventually, all segment points were obtained. Based on the MCM, an efficient method named DOM was proposed to fitting the discrete CL. Firstly, the DOM method calculated the curvature of CL points, extracted the dominant points which is composed of inflection points, the maximum curvature points and the chordal points according to the curvature. Then, the dominant points were approximated with least square (LS) fitting method. Finally, added the maximum over error CL into the dominant points and repeated the fitting process until the target spline was obtained. Simulations show that the proposed MCM method can extract segment points correctly, and the DOM method is superior in aspect of control points and computational efficiency comparing with traditional method. Besides, the NC machining experiments on a freefrom surfaces have indication the effectiveness and feasibility of the hybrid tool paths, which has certain academic guidance and applied merits in engineering.