On the cutting stability of the lathe under different working conditions

Abstract

To study the cutting stability of a lathe, this paper presents an experimental investigation of the limit cutting depth and the corresponding chatter frequencies of the lathe under different working conditions. Test results show that the limit cutting depths and the corresponding chatter frequencies of the same lathe will be quite different, as the cutting diameter and cutting position of the workpiece change, and the limit cutting depth will also be changed with the cutting speed and feed rate at the same chatter frequency. Test results also show that natural vibration or vibrations may occur in a sub-system or sub-systems of the lathe structure separately or simultaneously under appropriate conditions, thus leaving chatter marks on the machined surface that correspond to single frequency vibrations or multifrequency vibrations. The current standards for dynamic acceptance tests of the lathe specify that the workpiece diameter d 1 should be one quarter times the swing of the lathe. Actually this is good only for checking the dynamic behavior of the spindle-workpiece-tailstock sub-system and not for the lathe as a whole. The paper suggests that a testpiece twice as big ( d 2 = 1/2 D) should also be used to check the dynamic behavior of the bed-carriage sub-system.