Abstract: A device is provided for forming coils which are inserted into radially inwardly open slots of a stator or rotor plate pack of an electric machine. The device enables intermediate forming of coils disposed in specific slots in order to also allow insertion of the coils of a further winding in the same slots and thus allow free forming. The device comprises a holding device for the plate pack and a forming mandrel. The latter includes a plurality of radially extendable laminae distributed about the periphery thereof. Different groups of laminae can be extended by a predetermined radial path length by push rods which can be driven independently of one another in order to force outwardly, and form in certain slots, the coil strands that have been inserted into the slots. Further, forming rings which are axially movable relative to the plate pack are provided to enable forming of winding heads.