Guidline to Asses Geometrical Intolerance of Thin-Walled Blanks After Burnishing Process

Abstract

Application of lightweight material like aluminum alloy is increasing its importance in various industries due to effective reduction of structure weight and sequential advantages like reduction of greenhouse gas emission and carbon footprint. However, deflection of aluminum thin-walled blank during production by machining is a challenge that merits further studies. Burnishing as a non-metal removal finish-machining process is usually used as a final treatment in the production chain of samples. However, in burnishing of thin-walled structure, machining-induced residual stress causes dimensional and geometrical distortion followed by problems in manufacturing accuracy and mismatch in assembly. Therefore, to minimize the consequence of the abovementioned errors, the source of the distortion should be identified and minimized during machining since usually no further operation is placed in the production chain after burnishing. To effectively tackle this challenge, in the present study an analytical model is developed to find how the burnishing process factors i.e. pass number and static force together with initial blank size impact the distortion of thin-walled 6061-T6 plates. The curvatures which were derived from analytical model were compared to those of burnished samples measured by coordinate measuring machine. It was found from the results that the burnishing pass number because of its impact on work hardening and regeneration of stress together with blank size play crucial role on determining the sample’s distortion. It was obtained that with 2 pass burnishing results in minimizing the distortion of material. Moreover, the blank’s length to width ratio due to its impact on material stiffness in corresponding direction significantly impacts the deformation after unclamping. The results which were derived from analytical model were compatible well with experimental values in term of final distribution of residual stress and maximum height of distorted parts.