The influence of tool-path strategies and cutting parameters on cutting forces, tool wear and surface quality in finish milling of Aluminium 7075 curved surface

The curved parts of Aluminium 7075 alloy are extensively used in automotive and aircraft structures. In curved surface milling, the tool-workpiece contact changes continuously varying effective tool radius, active cutting speed and cutting forces all the time during machining. These variations lead to a change in metal removal mechanism from shearing to ploughing and vice-versa that determines the final product quality. In the present work, the tool-path strategies are investigated in the first phase wherein 3D offset found to be the best finishing strategy. Latter, the parametric analysis is performed by conducting the statistically designed experiments with 3D offset strategy to highlight the input-output correlations. The Khattree-Naik's equation/plot is used to analyse the multivariate data in milling and accordingly the better input parameters are selected. A ball-end tool imparting the entire tool face and cutting the surface from all-around with consistent cutting conditions enhances the tool life with a better finish. The results show that along with the magnitude of the force, a time lag (Delta t) and nature of force profile are equally significant in determining the tool wear and surface roughness.