Prediction of cutting forces and machining error in ball end milling of curved surfaces -I theoretical analysis

This paper presents a theoretical model by which cutting forces and machini ng error in ball end milling of curved surfaces can be predicted. The actua l trochoidal paths of the cutting edges are considered in the evaluation of the chip geometry. The cutting forces are evaluated based on the theory of oblique cutting. The machining errors resulting from force induced tool de flections are calculated at various parts of the machined surface. The infl uences of various cutting conditions, cutting styles and cutting modes on c utting forces and machining error are investigated. The results of this stu dy show that in contouring, the cutting force component which influences th e machining error decreases with increase in milling position angle; while in ramping, the two force components which influence machining error are ha rdly affected by the milling position angle. It is further seen that in con touring, down cross-feed yields higher accuracy than up cross-feed, while i n ramping, right cross-feed yields higher accuracy than left cross-feed. Th e machining error generally decreases with increase in milling position ang le. (C) 2001 Elsevier Science Inc. All rights reserved.