Shrink Wrap Machines

Compare shrink wrap L sealing systems and machines that provide the most common shrink wrap method. Wrapping and shrinking the product is done with machines commonly referred to as L sealers. Once the product is wrapped in the film, heat is applied by a heat chamber or a heat tunnel to shrink the film.

Manual L Seal Film is bonded and cut with an L shaped tool for all sealers in this group. The tool is mounted with a hinge attached to the rear of the work surface and is brought down on an arc closing at the work surface with the film between the toll and the work surface. This work surface and seal tool configuration causes the tool width and length dimensions to be the most prominent selection parameters. To define the maximum size (height, width and length) of a package that can be wrapped and sealed, a ratio of the package height and package width must be considered. The length of the package must then be within the length of the L tool. An operator places a package under and then draws down the tool and holds it down for a fixed length of time to bond and seal the film encasing the package. The closed pressure applied accomplishes the cut. The seal tool uses heat to bond the film. The tool, in the form of either a wire or knife, is heated upon demand, impulse, or continuously, which leads to three (3) types for the seal method parameter a) Impulse Wire, b) Hot Wire and c) Hot Knife.

Automated L Seal The Manual L Seal data parameters previously described also apply to Automated L Seal machines. With automated machines the Maximum Package Height becomes more significant, especially with conveyor use. On machines with in-feed conveyors, the L tool is usually mounted parallel to the work surface and is brought down perpendicular vs. with an arc as with the Manual L Seal machines. The L height (distance between the bottom of the raised L tool and the work surface) opening sets the maximum value for the package height. Some semiautomatic seal machines have the product item manually placed into the film by an operator and use pneumatic power to operate the L tool. These machines may have the L tool mounted on a hinge, similar to the Manual L Seal machines. In this design configuration, the maximum package height to package width ratio limit applies. In the database, the phrase W-arc-ratio appears where a specific Maximum Package Height numeric value cannot be used. A powered take away conveyor and possibly an in-feed conveyor can also be found on an Automated L Seal machine. Pneumatic powered optional features are used with semiautomatic and with fully automatic L Sealers.

Heat Tunnel After a product has been wrapped and sealed, a conveyor is used to transport it through a heated environment where the film shrinks conforming to the package dimensions. The conveyor Transport is of several forms. The one chosen depends on the characteristics of the product being transported. A Wire Mesh belt is perhaps the most common. A Teflon Mesh is wire covered with Teflon. A flat Solid Belt made from a variety of various fibreglasses, plastics and other materials, as well as conveyors made of Live/Dead Rollers are also frequently used. Some conveyors are fixed speed, but most are adjustable to meet the time requirements to properly expose the film for the shrinking process. Some manufacturers use packages per minute (Package/min) others use feet per minute (ft/min) to specify the transport rate. Either number appears as a maximum rate within the database