Stretch wrap

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A pallet loaded with corrugated fiberboard boxes being stretch wrapped Pallet wrapper.jpg
A pallet loaded with corrugated fiberboard boxes being stretch wrapped

Stretch wrap or stretch film, sometimes known as pallet wrap, is a highly stretchable plastic film that is wrapped around items. The elastic recovery keeps the items tightly bound. In contrast, shrink wrap is applied loosely around an item and shrinks tightly with heat. While it is similar to plastic food wrap, it is not usually made of material rated as safe for food contact.

Contents

It is frequently used to secure pallet loads to one another but also may be used for bundling smaller items. Types of stretch film include bundling stretch film, hand stretch film, extended core stretch film, machine stretch film and static dissipative film.

Materials

The most common stretch wrap material is linear low-density polyethylene (LLDPE), which is produced by copolymerization of ethylene with alpha-olefins, the most common of which are butene, hexene and octene. The use of higher alpha-olefins (hexene or octene) gives rise to enhanced stretch film characteristics, particularly in respect of elongation at break and puncture resistance. Other types of polyethylene and PVC can also be used. Many films have about 500% stretch at break but are only stretched to about 100–300% in use. Once stretched, the elastic recovery is used to keep the load tight.

There are two methods of producing stretch wrap:

Other properties such as break strength, cling, clarity, tear resistance, static discharge, etc. are also important.

Functions

In pallet unitizing, stretch wrap can have several functions:

Making sure boxes stay on the pallet and properly aligned is an important consideration in warehouse distribution, especially as the demands for increased throughput continues to rise.

Stretch wrappers

An automatic turntable wrapper Automatic turntable stretch wrapper.jpg
An automatic turntable wrapper
An automatic rotary arm wrapper Stretch Wrap Freedom 7525.jpg
An automatic rotary arm wrapper
An automatic rotary ring wrapper Enfardadora automatica.jpg
An automatic rotary ring wrapper

Stretch wrappers are devices used to apply stretch wrap. There are many types of stretch wrappers:

See also

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Extended core stretch wrappers are rolls of stretch film that have their internal core extended beyond their film roll creating a handle by which film can be wrapped.

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Mechanical brake stretch wrappers are manual stretch wrapping systems which consist of a simple structure supporting a roll of film to be stretched and a mechanical brake which acts on the film roll, creating resistance to turning and stretching the film as it is fed out.

<span class="mw-page-title-main">Turntable stretch wrapper</span>

Turntable stretch wrappers are a type of automatic and semi-automatic stretch wrapping system. A load is placed on a turntable, which rotates relative to the film roll, which is housed in a carriage attached to a vertical "mast" on which it may move up and down.

<span class="mw-page-title-main">Orbital stretch wrapper</span>

An orbital stretch wrapper is a means of applying stretchable plastic film to a load, consisting of a roll of stretch wrap supported on a vertical rotating ring and a means of passing a load through the ring's eye horizontally. Several designs are available.

Signode Finland, former Oy M. Haloila Ab, is one of the world's leading companies in the manufacture of pallet-wrapping machines. Signode Finland factories are located in Masku, Finland and Kardjali, Bulgaria.

<span class="mw-page-title-main">Packaging machinery</span>

Packaging machinery is used throughout all packaging operations, involving primary packages to distribution packs. This includes many packaging processes: fabrication, cleaning, filling, sealing, combining, labeling, overwrapping, palletizing.

References

  1. US 4102513,Guard, Twyman,"Film Wrapping Dispenser",published 1978-07-25
  2. US 4248392,Parry, John C.,"Apparatus for Application of Plastics Stretch Films",published 1981-02-03

Further reading