Apparatus and method for shrinkage of sheet-like thermoplastic packaging materials to products or combinations of products

There are a device (1) and a method for shrinking planar thermoplasticpackaging materials to products (3) or sets of articles is disclosed. The device (1) comprises a tunnel housing (5) having two openings through which enter the article (3) or sets of articles with their respective thermoplasticpackaging material in the tunnel housing (5) and can escape from the tunnel enclosure (5). Furthermore, the device (1) comprises a transport device (7), which provides a horizontal transport plane (30) for moving the articles (3) or sets of articles with their respective thermoplasticpackaging material through the tunnel housing (5). In the tunnel housing (5) thermal energy is introduced. An opening cross section of at least one of the apertures can be enlarged and reduced in size. The at least one device has at least arranged a positioned in the area of the respective opening and at least in sections in the tunnel housing (5) flap (4) comprising at least one flap (4) for increasing and decreasing the opening cross section of the respective opening to an angle and preferably perpendicular to the horizontal transport plane (30) oriented axis (20) in view of the tunnel housing (5) in the inward direction and in view of the tunnel housing (5) in the outward direction is pivotable.