Abstract: A welding and separating device for stacked plastic films has a heated welding and separating strip and a cooperating resilient counterpressure element which are moved together. The strip has a wedge-shaped separating knife with a comparatively small wedge angle and two welding members, one on either side thereof. Each welding member is formed to have a cross sectionally round surface. The welding members and the knife have comparatively deep V-shaped recesses therebetween. The counterpressure element is round in cross section and is aligned opposite the center of the separating knife. Separate spaced support bars press against the counterpressure element to deform the element and tension the films so that the surface of the resilient element is reduced as the knife and welding members press against the element. A process for welding employs support bars and a welding bar.