Investigation of chatter stability in high speed milling on thin ribs

Abstract

Chatter is a self-excited vibration that occurs during high speed machining of parts which is an undesirable phenomenon that affects work piece and also the tool. Chatter mainly depends upon the stiffness, the damping ratio of the material, the force applied and the clamped area. As the machined area continuously changes, the chatter stability of the work piece also changes continuously. The change in natural frequency of Aluminium 7010 T7651 thin rib during milling is calculated by using Modal analysis in ANSYS Workbench. The model is validated with published journal results and experimentally. Also, the scaled-down model of thin rib for same geometry is analysed for any change in natural frequency. The polynomial fit equation for finding instantaneous frequency of thin rib has been found which is applicable for same geometry irrespective of its scale. Using the equation, Stiffness is found and 2D Stability Lobe Diagram has been plotted and chatter free machining has been carried out experimentally in both stable and unstable regions to prove chatter zones. Also it was found that varying spindle speed is easier approach to avoid chatter during milling.