Study and simulation of critical factors affecting final quality in electromagnetically hemmed automotive aluminum

A previous study on electromagnetic forming (EM) hemming technology carried out in TECNALIA showed the real capability of this high speed deformation method to produce quality hemmed parts (Jimbert et al., J. Mater. Process. Technol. 211:916-924, 2011). Continuing with the development of this promising new application for the EM technology, some new experiments were run. The objective of this study is to focus on the critical processing factors that affect the final quality of the electromagnetically hemmed parts. For this purpose, an experimental plan was designed changing different input parameters and output quality parameters measured to quantify the results. The flange height limit was obtained for the studied experimental setup and was established at 10 mm. The bending radius and the gap between the inner and the outer part have to be keep to the minimum to increase final quality. In parallel to the physical experiments, EM hemming simulations were carried out using an EM loose coupling simulation method. An EM hemming process simulation of a circular whole part was carried out using shell elements. Results were compared with cross section simulations of the hemmed union using solid elements in order to analyze the importance of the type of element used for EM hemming simulation. Simulations revealed that solid elements reproduce quality aspects better than shell elements.