Feed rate optimization based on cutting force calculations in 3-axis milling of dies and molds with sculptured surfaces

Abstract

The use of CAD/CAM systems and NC machine tools for die and mold manufacturing offers considerable advantages over conventional methods, such as reduction in machining time and costs, and improvements in accuracy and reproducibility. However, the selection of cutting tools and machining strategy and parameters, which have a significant impact on overall machining efficiency and process reliability, still depends on the experience of the machinist or the NC programmer. Based on these considerations, this study had two major objectives: (a) develop a method for estimating the cutting forces in 3-axis milling so that the NC programmer can “optimize” the machining parameters; and (b) establish the “best” rough milling strategy to reduce machining time and cost. This paper concentrates on the first objective, namely on optimizing the feed rate to improve machining efficiency in end milling. By simulating the end milling process and predicting the cutting force in 3-axis milling of sculptured surfaces, an approach and the associated computer program have been developed to optimize the feed rate, already at the NC programming stage. The calculated cutting force, which includes the overall net effect of all process variables, is used as a feedback variable to adjust the feed rate. The method also allows the NC programmer to visualize cutting forces in a CATIA CAD/CAM environment.