Materials induced vibration in ultra-precision machining

In this paper, the development of a microplasticity model for predicting th e effect of crystallographic orientation on the shear angle and the chip fo rmation, as well as on the variation of micro-cutting force are discussed. The model forms a basis for the study of material induced vibration phenome non encountered in ultra-precision machining. Material induced vibration ha s its origin in the variation of micro-cutting force caused by the changing crystallography of the material substrate being cut. It is a kind of self- excited vibration which is difficult to eliminate solely by machine tool de sign or process control. The magnitude of such vibration inevitably affects the surface topography of the workpieces in ultra-precision machining, and this sets a limit on the performance of an ultra-precision machine. A fram ework of a model-based simulation system is proposed to determine quantitat ively the magnitude of the vibration and its effect on the surface topograp hy of a diamond-turned surface. Features predicted from the system are foun d to correlate well with experimental findings. (C) 1999 Elsevier Science S .A, All rights reserved.