Flow Thru Machines

Flow thru shrink wrappers, or flow through shrink wrappers are designed to wrap products in heat shrinkable plastic film as the product flows through the flow through shrink wrapper in a straight line. Flow through shrink wrappers are designed to create three kinds of heat shrinkable plastic film packages around the product. The first type of plastic film package has a heat-sealed seam in front of the package, a heat-sealed seam in back of the package, and an overlap static seal underneath the package, and is called a lap seal package. The second type of plastic film package has a heat-sealed seam in front of the package, a heat-sealed seam in back of the package, and a heat-sealed seam on the side of the package. This type of heat shrinkable plastic film package has a side seam. Flow through shrink wrappers are designed to seal and cut the film in front and behind the package (and in the case of a side seam package, to the side of the package) using either a hot wire seal and cut-off or a hot knife seal and cut-off. The third type of package that a flow through shrink wrapper can accomplish is called an inverted seal or package. An inverted flow through shrink wrapper creates a package that has a heat-sealed seam in front and behind the package, and a heat-sealed seam longitudinally across the top of the package.

Lap seal flow through shrink wrappers, or overlap seal flow through shrink wrappers, use a single flat roll of film that passes over a form to wrap the film completely around a product as the product passes through the form. The lap seal flow through shrink wrapper overlaps the film below the product. Because this overlap of film is not actually sealed until the package passes through a heat shrink tunnel, the overlap seal is also referred to as a static seal. After the film is overlapped below the product, the lap seal flow through shrink wrapper passes the product through lateral seal jaws that seal the front of the current package, seal the back of the next package, and separate the packages by cutting the film between the two packages.

侧缝流过收缩包装设计d to use center folded heat-shrinkable film to wrap the product. The side seam flow through shrink wrappers pass the center folded film over a forming plow that orients the film below and above the infeed conveyor. The product is transferred onto the film with the folded portion of film above the package. The heat-shrinkable film is then passed through a seaming device that seals the film to the side of the product. The side film sealer also trims excess film beyond the seal. The side seam flow through shrink wrapper then passes the wrapped product through lateral seal jaws that seal the back end of the current package, seal the front end of the next, and cut the film between the seals.

Inverted flow through shrink wrappers also use single flat rolls of film. An inverted flow through shrink wrapper is designed to have the product placed on the film rather than on a belt or lug chain to carry the product through the heat-sealing jaws. The heat shrinkable film is formed up around the product through the use of plows. The excess film above the product is passed through a mechanism that seals the film above the package and trims the excess film. The inverted flow through shrink wrapper then passes the product through lateral film sealing jaws that are designed to form the trailing seal for the current package, form the leading seal for the next package, and cut the film between the seals to separate the packages.