Evaluation and Improvement of Productivity in High-Speed NC Machining

Abstract

The productivity of machining centers is influenced inherently by the quality of NC programs. To evaluate productivity, first an effective feedrate factor and a productivity evaluation factor are proposed. It has been found that 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/deceleration or time constants. Then an NC program simulator has been developed to evaluate productivity. With the simulator, the machining time can be calculated 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 productivity can be improved by increasing the acceleration and average travel and reducing the vectorial variation of the tool rather than the command feedrate. [S1087-1357(00)01303-4]