Finite element and experimental investigation of up- and down-milling in thin-wall machining

This study presents a comparative investigation of up-milling (conventional) and down-milling (climb) strategies in the machining of thin-walled components through finite element simulation and experimental validation. A three-dimensional explicit dynamic model was developed in LS-DYNA to analyze deformation behavior, stress evolution, and energy response under both cutting modes. The analytical formulation was based on the Kirchhoff–Love plate assumption, considering wall slenderness and cutting-force distribution along the tool path. Thin-wall specimens made of Al6061-T6 aluminum, each 2.5 mm thick and 35 mm high, were machined under identical cutting conditions to validate the simulation results. The numerical outcomes revealed that cutting direction strongly influences deformation characteristics: up-milling caused alternating outward deflection with higher oscillation amplitudes, while down-milling produced smoother inward deflection and more stable wall deformation. Energy analyses showed that the total internal energy absorbed in climb milling was nearly twice that of conventional milling, indicating improved mechanical stability. Experimental measurements of wall deflection and surface finish closely matched the predicted results, confirming the accuracy of the simulation. The findings highlight the superior performance of down-milling for achieving dimensional precision and surface integrity in thin-wall machining.