Accurate estimation of cutting time based on control principle of machine tool

The accurate estimation of cutting time before beginning a cutting process is necessary to improve the productivity of machining. Commercial computer-aided machining (CAM) systems estimate the cutting time by dividing the tool path length by the designated feed rate in a numerical control (NC) program. However, the actual cutting time generally exceeds the estimated cutting time for curved surfaces because of the acceleration and deceleration of the NC machine tool. There are systems that estimate cutting time while considering acceleration and deceleration along the controlled axes, but these are applicable only to particular machine tools. In this study, a flexible system for the accurate estimation of cutting time, based on the control principle of a machine tool, is developed. Experiments to estimate cutting time are conducted for the machining of complex shapes using two different NC machine tools. The actual cutting time is compared with the cutting time estimated by the developed system and that by a commercial CAM system. The estimation error of the proposed system is only 7%, while that of the commercial CAM system is 51%.