Optimization of cutting parameters for finish end milling CFRP under vortex-cooled compressed air

Abstract

Carbon fiber reinforced plastics (CFRP) offer several advantages in the aeronautical and automotive industry due to their combination of lightweight, high strength, and corrosion resistance. CFRP parts are usually produced in near-net-shape; however, additional machining processes are often required for achieving desired dimensional accuracy and surface finish. Thus, this work evaluates the influence of the cutting parameters in CFRP end milling to generate a better surface finish. The experiment was designed using a three-factor, three-level Box-Behnken considering feed rate (f), axial depth of cut (ap ), and cooling conditions (cc) as controllable factors, and roughness parameters (Ra , Rq , Rz , Rt ) as response variables (the occurrence of defects was evaluated qualitatively). Results indicated a strong influence of the quadratic effect of axial depth of cut and its interactions with feed rate and cooling condition on the roughness values and a milder but significant influence of the feed rate and cooling conditions. Multivariate analysis returned the optimum level of input parameters (f = 0.21 mm/rev and ap = 0.8 mm with cooled compressed air), resulting in Ra = 1.58 µm, Rq = 1.98 µm, Rz = 9.39 µm, Rt = 13.63 µm. Also, no defects were observed after machining under the optimum conditions.