Resource-efficient manufacturing route for metal sandwich components

Compared with conventional manufacturing methods, additive manufacturing (AM) enables the production of resource-efficient parts with complex geometries, particularly for sandwich sheets with tailored core structures. In this work, semi-finished sandwich sheets are produced by powder bed fusion and subsequently formed (bending and deep drawing). This innovative process route can improve the manufacturing efficiency with respect to production time, post processing time, and less material usage since fewer support structures are required. At the same time, the mechanical properties of the formed parts are improved. To overcome build-chamber limits, a new variant uses conventionally manufactured cold-rolled face sheets joined to the additively manufactured core structures either by joining by forming or by material fit. For joining by forming, it is concluded that the joint strength in shear-tensile test is determined by the strength of the face sheets. Face-sheet wrinkling and detachment from the core structure are the main failure modes for this joining method. The process window for the minimum bending ratio (punch radius to sandwich-sheet thickness) is also determined, which should be less than 3.33. For the case of material fit, the face sheets are joined to the core structure by resistance welding, in which different joint-area geometries are investigated to alter the contact area. Experimental and numerical results show that humps are necessary to achieve complete joining between the core structure and the face sheets. Additionally, the results show that increasing the weld current has an insignificant effect on shear strength.