Analytical and Experimental Investigations of Instability in Milling Process and Studying the Effect of Cutting Parameters and Tool Stiffness

Using cutting tool vibration equations in x and y directions, the chatter phenomenon in milling process is modeled. To solve these equations, cutting tool structural characteristics, such as natural frequency, damping ratio, and its stiffness in x and y directions must be known. For finding these properties, “Modal Test” is performed and its results are analyzed. The suggested analytical model for chatter phenomenon is tested experimentally in different axial depth of cut and its correctness is proved. The critical depth of cut in slotting Titanium alloy Ti6Al4V with Carbide tool is achieved both experimentally and analytically about 5 mm. After validation the suggested model for predicting chatter, the effect of cutting speed, endmill stiffness, and radial depth of cut on cutting system stability are simulated. Increasing the cutting speed causes system switches between stable and unstable conditions for several times. This is because of the special shape of the Stability Lobe Diagram (SLD). Increasing the endmill stiffness and decreasing the radial depth of the cut or tool-workpiece engagement make the process more stable.