The productivity of machining centers is influenced directly by the quality of NC programs. Conventionally it was effective to calculate machining time based on the values commanded in the NC program. However, as cutting speed/feedrate and machining accuracy increase, more factors have to be considered in the estimation of productivity. In this research, such factors have been found. These are the feed acceleration and average per-block feed distance, besides command feedrate. Furthermore, an effective feedrate factor and a kinematic factor are suggested to express the relations among the above three factors. With the kinematic factor improvements on productivity can be made by changing appropriate parameters in the light of specific conditions. Based on the above analysis, an NC program evaluator was developed to investigate the productivity. With the evaluator, the machining time can be accurately calculated even in high-speed and high-precision machining which is impossible by a conventional CAM tool or an NC controller. Applying the evaluator, three actual NC programs used in high-speed and high-precision cutting were analyzed and the results show that increasing the acceleration and per-block feed distance rather than command feedrate is effective to productivity in high-speed and high-precision cutting. (C) 1999 Elsevier Science Ltd. All rights reserved.