Effects of tool helix angles on machined surface morphology in tilt side milling of cantilever thin-walled plates

Abstract

For milling the side wall surfaces of cantilever thin-walled plates, to tilt the tool to a proper angle could decrease the cutting force component in the direction of the lowest stiffness of the plates, and then mitigate the chatter, resulting in the improvement of the machined surface finish. The tool helix angle and tilt angle are the two major variables determining the cutting force component, accordingly having significant effects on the machined surface morphology. In this paper, these effects are investigated through experiments with solid end mills of different helix angles.With the surface roughness Ra as the quantification assessment parameter for machined surface morphologies, variations of surface morphologies not only with the tool tilt angles but also with the tool helix angles are investigated. The mathematical model expressing the relation between the tool helix angle and the corresponding optimal tilt angle is built when the quality of the machined surfaces is the best. For better understanding the effects of these two variables on the dynamic vibrations of the workpiecethat directly contributes to the formation of surface morphologies, especially chatter marks, the instantaneous vibration displacements of plates during the milling process are also measured by a laser range sensor, and the effects on the surface roughness are analyzed. This study could provide guidance for process parameters optimization in milling the sidewall surfaces of thin-walled components.