Modeling and Optimization of Surface Roughness in Incremental Sheet Forming using a Multi-objective Function

Abstract

As a critical product quality constraint, surface roughness is regarded as a weak point in incremental sheet forming (ISF). It is of great importance to identify the impact of forming parameters on the surface roughness and optimize the surface finish at the production stage. This paper proposes a systematic approach to modeling and optimizing surface roughness in ISF. The quantitative effects of four parameters (step down, feed rate, sheet thickness, and tool diameter) on surface roughness are analyzed using the response surface methodology with Box–Behnken design. The multi-objective function is used to evaluate the overall surface roughness in terms of the tool-sheet contact surface roughness, i.e., internal surface roughness and the noncontact surface roughness, i.e., external surface roughness. Additionally, the average surface roughness (R a) on each surface is measured along the tool-path step-down direction taking the impact of sheet roll marks into account. The optimal conditions for the minimization of overall surface roughness are determined as step down (0.39 mm), feed rate (6000 mm/min), sheet thickness (1.60 mm), and tool diameter (25 mm). This study shows that Box–Behnken design with a multi-objective function can be efficiently applied for modeling and optimization of the overall surface roughness in ISF.