Shrink vs Stretch Wrapping, How They Wrap Up.

While pallet packaging may not be the most alluring aspect of a packaging operation, choosing a pallet packaging method can significantly impact overall profitability, sustainability, and distribution chain performance.

There are three recognized methods available for pallet packaging: conventional spiral stretch-wrapping, heat shrink-hooding, and stretch-hooding. Each method has its advantages and disadvantages depending on the specific application.

Spiral Stretch-Wrapping

Spiral stretch-wrapping is the most common method for pallet packaging and provides a low-cost method for securing pallet loads for shipping. The equipment uses cast or blown linear low-density stretch film, which is pre-stretched 60 to 400 percent, depending on equipment type, before being wrapped around the pallet load. There are many manufacturers of spiral stretch-wrapping equipment, and both equipment and film are readily available through a large number of distributors.

The stretch-wrap film can be applied in a variety of patterns depending on the load stability and protection required. A myriad of types are available, from turn-table models—where the operator manually cuts the film and attaches the film tail to the pallet load—to fully automatic rotary-arm, or satellite, models with top-sheet dispenser, automatic film roll change, and speeds up to around 100 pallet loads per hour.

While spiral stretch-wrapping technology offers a cost-effective pallet packaging solution in some applications, there are drawbacks. Because the film is applied with multiple layers of a relatively narrow overlapping film band, spiral stretch-wrapping provides little stability when compared to a hood-style method, as there is insubstantial vertical holding force unitizing the pallet and the load.

For protection against the elements, a top-sheet is often applied to the pallet load. This provides nominal protection, but is practically insufficient for outdoor storage and shipping on open flatbed trucks in inclement weather. Accordingly, the cost of building additional warehouse storage capacity, as well as costs associated with protective tarpaulins for flatbed shipping, must be considered when comparing spiral stretch-wrapping with a hood-type method.

The physical properties of stretch-wrap film present challenges that should also be considered when evaluating different pallet packaging methods. Among other things, the overlapping layers of stretch-wrap film tend to trap moisture, and the cling additive in the film attracts dirt and dust. Moreover, relatively low-volume film rolls mean shorter film change intervals, thus reducing machine availability and increasing operating costs.

Accurately forecasting and controlling the cost of consumables (stretch-wrap film, in particular) can also be difficult, as individual operators often follow their own preferences in applying stretch-wrap film.

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