Novel approach for reducing thinning during forming of foil metal

The mobility sector is one of the largest contributors to greenhouse gas emissions in the European Union. One approach to reduce these emissions and thereby reach the climate goals set by the European union is the use of alternative drive concepts, such as the hydrogen fuel cell. The economic feasibility of the hydrogen fuel cell depends on its performance which is mostly determined by the volumetric flows of reactants conveyed within the cell. In this context, the key component is the bipolar plate, as its channel depth defines the volumetric flows of reactants. The channel depth is, however, limited by the formability of the material being used and the occurring sheet thinning during forming. This paper presents a novel approach of segmental forming, meaning the forming of individual channels in a defined sequence. The aim is to reduce local stress concentration in the component and to homogenize the spatial thinning within the component in order to avoid a pronounced local sheet thinning. Therefore, five channels are formed by conventional forming in a single step and by segmental forming. The results are then analyzed in terms of the thinning of the sheet thickness that occurs and conclusions are drawn in terms of the stress states that occur.