NC program evaluator for higher machining productivity

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