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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.

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
An automatic rotary arm wrapper
An automatic rotary ring wrapper

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

See also

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