Probabilistic design of aluminum sheet drawing for reduced risk of wrinkling and fracture

The exclusion of inherent process variations in the current deterministic design methods for sheet metal forming can lead to very unreliable result that may cause high scrap rate, frequent rework, machine shut down and thus huge loss of profit. In this paper, a general approach is presented to quantify the uncertainties and to incorporate them into RSM model so as to conduct probabilistic based optimization. As an application, deep drawing process of Hishida part is analyzed. Given the blank shape and tooling, a probabilistic design is successfully carried out to find the optimal combination of blank holder force and friction coefficient under the presence of variation of material properties. The result shows that by the probabilistic design, the quality index (average defect rates of wrinkling and fracture) improved (reduced) 42% over the traditional deterministic design. In a mass production environment, the achieved quality improvement is huge.