Theoretical model and experimental investigation of machined surface roughness considering plastic side flow

Plastic side flow in metal cutting significantly affects the machined surface quality, which is related to cutting parameters and tool geometry. Nevertheless, the existing studies mainly focus on its effects and causative factors in plastic deformation, missing in-depth research on the forming process and theoretical modeling. To establish an accurate surface roughness prediction model, this paper deeply analyzed the cutting process of 7075 aluminum alloy under different feed rates (f) and tool tip radii (r_c) based on the metal cutting principle and plastic side flow theory. The results suggested that the plastic side flow model proposed in this paper was consistent with the experimental results when f < 0.1 mm/r and r_c < 0.8 mm, and the increasing f and decreasing r_c were unfavorable to the plastic lateral flow. Additionally, the surface roughness prediction model matched with the actual experiments, with relative deviations ranging from 3.1 % to 9.8 %. The highest cutting surface quality (∼2 µm) was obtained at the preferred critical parameters (f= 0.5 mm/r and r_c= 0.4 mm). Cutting surface formation was shown to be a competition result between plastic side flow, kinematic factors, and elastic recovery, whose coupled action determined the final surface. Consequently, this study proposed a surface roughness prediction model considering plastic side flow, offering guidance for cutting theory and practical production.