Accurate 3-D cutting force prediction using cutting condition independent coefficients in end milling

The instantaneous uncut chip thickness and specific cutting forces have a s ignificant effect on predictions of cutting force. This paper presents a sy stematic method for determining the coefficients in a three-dimensional mec hanistic cutting force model-the cutting force coefficients (two specific c utting forces, chip flow angle) and runout parameters. Some existing models have taken the approach that the cutting force coefficients vary as a func tion of cutting conditions or cutter rotation angle. This paper, however, c onsiders that the coefficients are affected only by the uncut chip thicknes s. The instantaneous uncut chip thickness is estimated by following the mov ement of the position of the center of a cutter. To consider the size effec t, the present method derives the relationship between the re-scaled uncut chip thickness and the normal specific cutting force, K-n with respect to t he cutter rotation angle, while the other two coefficients-frictional speci fic cutting force, K-f and chip flow angle, theta (c)-remain constant. Subs equently, all the coefficients can be obtained, irrespective of cutting con ditions. The proposed method was verified experimentally for a wide range o f cutting conditions, and gave significantly better predictions of cutting forces. (C) 2001 Published by Elsevier Science Ltd.