Tool orientation optimization of 5-axis ball-end milling based on an accurate cutter/workpiece engagement model

Abstract

Tool orientation in 5-axis ball-end milling plays a significant role in machining efficiency and accuracy. The cutter/workpiece engagement varies with tool orientation continuously including lead and tilt angles during machining, which results in the obvious time-varying characteristic for consecutive cutting forces. Considering tool orientation, actual cutter runout and cutter motion process, an accurate calculation model for instantaneous cutter/workpiece engaging process in 5-axis ball-end milling is proposed based on an improved analytical method with high order Taylor formula, which can reach an excellent accuracy. Then base on the cutting force model, the tool orientation optimization strategies with a flexible cutter and rigid workpiece for roughing and finishing milling operation are further presented. For the three kinds of geometrical characteristic (plane, cylindrical and spherical surface), this study analyzes the influence of tool lead and tilt angles, and step over on the maximum cutting force and form error, and finally obtains an optimal tool orientation to realize a high efficiency and accuracy machining.