Evaluation and improvement of productivity in high-speed NC machining

The productivity of machining centers is influenced inherently by the quali ty of NC programs. To evaluate productivity, first an effective feedrate fa ctor and a productivity evaluation factor are proposed. It has been found t hat in high-speed machining, these two factors depend on a kinematic factor which is a function of (1) command feedrate, (2) average per-block travel of the tool, (3) moving vectorial variation of the tool, and (4) ac/deceler ation or rime constants, Then an NC program simulator has been developed to evaluate productivity. With the simulator the machining time can he calcul ated accurately and the cutting conditions can be extracted. Finally, three NC programs were implemented on high-speed machining centers and analyzed by the simulator. It was found that in mold and die machining, the producti vity can he improved by increasing the acceleration and average travel and reducing the vectorial variation of the tool rather than the command feedra te. [S1087-1357(00)01303-4].