Sandwich panels may include an intermediate thermoplastic layer disposed between two metallic cover layers. Some methods for welding a sandwich panel to a metallic component may involve heating a region of the sandwich panel with a preheating current so that the thermoplastic layer is softened and by compression of the cover layers is displaced from the welding region. A tack-welding current flowing between first and second welding electrodes may weld the cover layers together, and a welding current may be used to weld the metallic cover layers to the metallic component. In some cases, the first welding electrode may be in contact with one of the metallic cover layers, and the second welding electrode may be in contact with the metallic component. As a result, the sandwich panel may be joined to the metallic component in a short cycle time without blisters and faults arising in the sandwich component.