The Development of Stretch Wrap Machines in Packaging

Stretch wrap machines first came into use in the 1970s as a replacement for steel strapping, plastic banding, twine, rubber bands, and heat shrink polyethylene bags as a method of unitizing products for shipment. Pallet wrap film had many advantages over these other products and quickly became the preferred method for palletizing and unitizing loads. Among the important benefits were increased packaging speed, greater safety and ergonomics, and substantially reduced material cost. When first introduced, films were applied by hand in many applications, including high volume operations. This occurred because equipment technologies and designs were still in the developmental stages, and because even hand applied films had a productivity advantage over alternate packaging methods.

Equipment Designs and Evolution

Early stretch wrap machines utilized what is referred to as a core braking system, in which braking tension was applied to the roll of film, causing it to stretch as the pallet pulled film away from the roll as it rotated on a turntable. Many of these machines worked with wide web film rolls, so that the entire width of the pallet was wrapped in a single layer or web. Spiral wrapping equipment worked with a narrower roll, usually 20" in width, which moved up and down on a carriage as it completed a wrap cycle. This caused the film to create a series of overlapping layers around the pallet, and allowed it greater stretch. Over time, film formulations became more sophisticated, with a capacity for stretch greater than could be achieved with conventional braking systems. Equipment manufacturers began to equip stretch wrap machines with prestretch rollers, which stretched the film before it was applied to the load. These braking systems doubled or tripled film stretch, producing significant film cost reductions, especially for high volume users. Later, powered prestretch rollers, which allowed even greater prestretching of film, grew in popularity with high volume shipping operations, where even a few pennies of film savings per load translated to tens of thousands saved per year.

Stretch Wrap Machines Today

All types of braking systems can still be found in pallet wrapping equipment today, but they are carefully matched to the requirements of the application. The additional expense of powered prestretch units normally cannot be cost justified in lower volume shipping operations. However, many machines can be retrofitted with more sophisticated braking systems when packaging volume increases. The greater modularity of today’s equipment often allows distribution centers and manufacturing facilities to reduce film costs without purchasing new equipment. Fully automatic systems have been designed to unitize conveyorized loads inline in high speed operations. Horizontal wrappers, sometimes referred to as ring wrappers or orbital wrappers, are ideal for long, heavy, or awkwardly shaped materials.

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