It is standard to shrink-wrap palletized goods in the manner described in U.S. patent application Ser. No. 07/454,774 filed Dec. 21, 1989, by first placing a thermoplastic lower foil atop a pallet with edges of the foil projecting laterally past the pallet and then stacking goods on the pallet atop the foil on the pallet within the edges of the foil. The lower edge of a downwardly open heat-shrinkable foil hood is held as the hood is fitted downward over the stack on the pallet until the lower edge is generally below the stack. This lower edge is then gripped below the stack and the foil hood is shrunk from top to bottom around the stack while continuing to grip the lower edge below the stack. Finally the foil hood is welded to the outer edge of the lower foil.
In such an arrangement the pallet is invariably moving horizontally on a transport device, typically a conveyor belt and the hood is heated and shrunk by a vertically displaceable heater ring that can fit around the palletized stack. In order to preliminarily warm and partially shrink the hood to eliminate air trapped therein, the shrink ring is first displaced down over the goods to a lower position where it is activated and then moved up. Once the ring is at the upper end of the goods it is then slowly brought downward, shrinking the hood tightly around the goods. When the wrap is fully shrunk, the ring is lifted up past the top of the stack and the conveyor transports the shrunk-wrap palletized goods horizontally away so that the operation can be repeated with the next load.
Thus for each shrinking operation the shrink ring must execute a useless downward travel from its starting position to the bottom of the goods so that it can do the initial bottom-to-top preshrinking, then after the top-to-bottom final shrinking a second useless upward stroke to get out of the way so a new package can be brought into line. Thus out of the four vertical movements, two are wholly unproductive.