The bag closing machine receives the cartons arriving from the production line and brings them inside, where a special group collects the overflowing bag from the outside and stretches it upwards. Nearly the end of this operation, two trailers especially designed, goes inside the bag and widen, causing the tensioning of the upper part to prepare it for the welding. A sealer makes the welding, that can be continuous or dotted. Once the sealing is completed, the carton arrives to the second station where the flaps are folded. The cycle is then finished, the group goes back to its original position and the belt starts, emptying the area for a new cycle on the arriving box.