Abstract: In view of the difficulty of prediction of CNC milling performance of the complex free-form surface, the curvature distribution value is proposed to evaluate CNC machining efficiency and machining accuracy. Equal-interval tool paths are planned on the constructed cutter location surface. Tool path length and maximum scallop-height are regarded as the evaluation index of achining efficiency and machining accuracy respectively. The influence of curvature distribution value on the tool path length and maximum scallop-height is investigated. Experimental results show that it is valid for this tool path mode to conduct CNC milling of free-form surface. Analytical results show that along with the increase of curvature distribution value, both tool path length and maximum scallop-height increase, thus reducing machining efficiency and machining accuracy. In addition, when the curvature distribution value is less than 0.5 mm–1, the machining efficiency decreases by only 7 %, but the machining accuracy decreases by 6-7 times. Therefore, the curvature distribution value can be used to evaluate and predict the CNC machining performance of complex free-form surface.

Key words: CNC milling, Curvature distribution, Free-form surface, Maximum scallop height, Tool path length