Identification of stability lobes in high-speed machining of thin ribs

High speed machining of low rigidity structures is a widely used process in the aeronautical industry. Along the machining of this type of structures, the so-called monolithic components, large quantities of material are removed using high removal rate conditions, with the risk of the instability of the process. Very thin walls will also be milled, with the possibility of lateral vibration of them in some cutting conditions and at some stages of machining. Chatter is an undesirable phenomenon in all machining processes, causing a reduction in productivity, low quality of the finished work pieces, and a reduction of the machine-spindle’s working life. In this study, a method for obtaining the instability or stability lobes, considering dynamic behaviors of machine structure is presented. Thus a stability lobe diagram (SLD) has been developed analytically for machining of thin ribs. The frequency response function (FRF) of the milling process has been predicted along with real and imaginary parts. The mathematical tool MathCAD 8 Professional is used to simulate the FRF and stability lobes. The experiment setup is proposed to find the impulse response of the machine structure at tool tip. Finally the stable and unstable region for high speed machining process has been predicted analytically.