Investigation of Effects of Material Dimensions on Wrinkling in Flexforming Process

Sheet metal forming processes are very common manufacturing and leading processes in automotive and aerospace industries. Flexforming is one of the sheet metal forming processes which is preferable due to its flexible manufacturing capabilities and its ability to produce multiple parts simultaneously. Convex contoured shaped parts are very much used in aerospace structures which are mostly produced by flexforming. Wrinkling is a characteristic defect for those kinds of parts. Prediction of wrinkling before manufacturing is highly crucial in order to reduce scrap rates, labor time, and other unexpected costs. In this research work, extensive amounts of experiments are conducted on flexforming press, and the process parameters such as material condition, contour radius, flange length, and material thickness which induce wrinkling are investigated in detail. Results have shown that sheet thickness is the most effective parameter, and as the sheet thickness is increased, wrinkling tendency is reduced extensively. Besides, increasing convex contour radius decreases wrinkling occurrence. Experimental findings are then used to generate wrinkling limit diagrams in which safety and failure zones are specified for different material conditions and sheet thicknesses. The developed diagrams might help to designer who can design defect free parts, reduce scrap rates, and reduce production costs significantly.