Modeling and optimization of a ball-burnished aluminum alloy flat surface with a crossed strategy based on response surface methodology

In this work, a new ball-burnishing strategy, in two crossed passes, was applied on the flat machined surface of 2017A-T451 aluminum alloy to investigate the influence of three classical ball-burnishing factors (burnishing speed Vb in mm/min, depth of penetration ab in μm and lateral feed f in mm) on the treated surface integrity enhancement. Experimental work is based on the application of an experimental face-centered composite design (CCD) formed by three factors at three levels. The mathematical modeling of the average roughness Ra, of the mean spacing of roughness profile irregularities Sm and of the surface hardness HIT of the treated surfaces was performed by the response surface methodology (RSM). Best ball-burnished surface integrity has been established by the application of optimal ball-burnishing studied factors (Vb = 500 mm/min, ab = 40 µm, and f = 0.2 mm). High surface quality is then characterized by a gain in average roughness Ra of 81 %, an enhancement in the mean spacing of profile irregularities Sm of 34 % and an improvement in surface nano-hardness HIT of 17 % when compared to the machined surface. Machined and ball-burnished optimized surface characterization confirms surface finishing process power and contribution to surface integrity enhancement of treated flat surface.