The warehousing and transportation of merchandise has progressed essentially from the basket and cart to the highly efficient temporary storage and cargo handling of the present day. Traditionally, warehousing technology has employed racks of varying designs to store units of merchandise and/or where the packaging technique permits, the utilization of palletizing procedures. Pallets classically are provided as wood slat platforms combined by nailing or the like with supporting runners. Merchandise carried upon the pallet platforms is held in place by a variety of schemes such as boxing, banding, or blister packaging. Conventional palletizing approaches are received with disfavor for many merchandising and transportation applications. When palletized merchandising units are stacked one upon the next, there is a tendency for such stacks to lean. Generally, the palletized units will contain a substantial number of cardboard boxes carrying merchandise. Often, the runners or the like of an upwardly-disposed pallet will indent or distort the upwardly-disposed goods-carrying boxes within a lower level palletized unit. Nails and like connectors utilized with wooden pallets often damage adjacent units during handling. Particularly where the boxed merchandise is intended for delivery into the retail trade, blemished or distorted cardboard boxes must be replaced, a procedure requiring an unpacking of the palletized units, reboxing of the merchandise, and reassembling the palletized units. The handling of the palletized units typically is carried out by the ubiquitous forklift truck.
Over the past few decades, another form of palletizing, sometimes referred to as "slipsheet" palletizing has gained substantial popularity. With this approach, assemblies of merchandise-carrying cardboard boxes or similar assemblages are stacked one upon the other with the interposition of a thin polymeric slipsheet between adjacently stacked units. A variation of the forklift truck is employed (herein deemed a "lift truck") wherein one or more platen surfaces are provided at the location of conventional forked tines in conjunction with a pushing and retracting mechanism. In initially stacking one unit upon the top of another with interposed slipsheets, the pushing features of the lift truck are employed. To remove a top stacked unit from a next lower unit, a gripping device associated with the retracting mechanism grasps an outwardly disposed flap extension of the slipsheet and pulls the slipsheet and unit disposed thereon onto the lift truck platen. Unit assemblages weighing, for example, up to about 2,000 pounds, are stacked and manipulated with this procedure.
A variety of advantages accrue with the slipsheet palleting approach. Initially, they are observed to be much less expensive than pallets, for example by a factor of about 6. However, the cost of the slipsheets generally is a function of their thickness and size. In this regard, the thickness of the polymeric sheets is selected in accordance with the size and weight of the assembled merchandise units involved. Pallets and/or slipsheets typically are transported with merchandise and seldomly returned. Thus, initial significant savings are realized with their use. Assemblages or units used with the slipsheets stack straighter and tend not to cause damage to adjacent units during the course of handling. Damage due to wooden pallet runners and the like is avoided to the extent that many business entities require the use of slipsheet palletizing with respect to the products which they are purchasing.
While the above advantages are realized with the utilization of slipsheet palletizing, the approach is not without flaws. Principal among the features detracting from slipsheet palletizing systems is the dynamic relationship extant between the slipsheets with their associated loads and the gripping and retracting mechanism utilized for cargo handling. In this regard, as a slipsheet tab is grasped and the retracting mechanism is activated, the top of the next lower slipsheet palletizing unit may be drawn into the tips of the mechanism platen. Also, the tolerancing or play inherent in such mechanisms may cause the platen tips to be driven into that same region of the next lower unit. This action usually results in damage to the tip-contacted boxes and/or goods contained therein which are located at the top of the lower adjacent unit. Such damage typically is corrected by replacement, reboxing, and reassemblage of the unit. For large warehousing installations, the annual cost for such damage can be quite substantial. Often, those lost products are not readily reboxed or replaced, resulting in "short shipping" to the detriment of the purchaser. Such upper level damage well may be exacerbated by virtue of the sharpness of the platen tips. Lift truck operators often are observed to operate the trucks in a manner wherein the platen tips slide upon the concrete floors of a warehouse, thus to effect a sharpening of them.
Another detracting feature of the slipsheet palletizing system is concerned with the slipsheet tabs extending from the stack. The gripping and retracting mechanisms of the lift trucks often tear them off. The remedy typically requires that personnel unpack the units by hand at their elevated location and then reassemble the units at floor level. The cost associated with this corrective procedure is apparent. To ameliorate this problem, the slipsheets may be formed having tabs extending from multiple sides. Unfortunately, multiple side access often is not available to the lift trucks. Thus, while slipsheet palletizing systems have a variety of advantageous aspects, their use also invokes a substantial detracting cost element.