Stretch wrap

Last updated
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

Related Research Articles

<span class="mw-page-title-main">Rotary dial</span> Component that allows dialing numbers

A rotary dial is a component of a telephone or a telephone switchboard that implements a signaling technology in telecommunications known as pulse dialing. It is used when initiating a telephone call to transmit the destination telephone number to a telephone exchange.

<span class="mw-page-title-main">Wire wrap</span> Electronic component wiring technique

Wire wrap is an electronic component assembly technique that was invented to wire telephone crossbar switches, and later adapted to construct electronic circuit boards. Electronic components mounted on an insulating board are interconnected by lengths of insulated wire run between their terminals, with the connections made by wrapping several turns of uninsulated sections of the wire around a component lead or a socket pin.

<span class="mw-page-title-main">Counterweight</span> Equivalent weight that balances a mechanical system

A counterweight is a weight that, by applying an opposite force, provides balance and stability of a mechanical system. The purpose of a counterweight is to make lifting the load faster and more efficient, which saves energy and causes less wear and tear on the lifting machine.

<span class="mw-page-title-main">Dynamic braking</span> Use of the traction motors as generators when slowing a vehicle

Dynamic braking is the use of an electric traction motor as a generator when slowing a vehicle such as an electric or diesel-electric locomotive. It is termed "rheostatic" if the generated electrical power is dissipated as heat in brake grid resistors, and "regenerative" if the power is returned to the supply line. Dynamic braking reduces wear on friction-based braking components, and regeneration lowers net energy consumption. Dynamic braking may also be used on railcars with multiple units, light rail vehicles, electric trams, trolleybuses, and electric and hybrid electric automobiles.

<span class="mw-page-title-main">Baler</span> Farm machine for creating hay bales

A baler or hay baler is a piece of farm machinery used to compress a cut and raked crop into compact bales that are easy to handle, transport, and store. Often, bales are configured to dry and preserve some intrinsic value of the plants bundled. Different types of balers are commonly used, each producing a different type of bale – rectangular or cylindrical, of various sizes, bound with twine, strapping, netting, or wire.

<span class="mw-page-title-main">Caster</span> Undriven wheel that is designed to be attached to the bottom of a larger object

A caster is an undriven wheel that is designed to be attached to the bottom of a larger object to enable that object to be moved.

<span class="mw-page-title-main">Train stop</span> Railway safety device

Part of a railway signalling system, a train stop, trip stop or tripcock is a train protection device that automatically stops a train if it attempts to pass a signal when the signal aspect and operating rules prohibit such movement, or if it attempts to pass at an excessive speed.

<span class="mw-page-title-main">Shrink wrap</span> Polymer used to bundle boxes on a pallet for transport

Shrink wrap, also shrink film, is a material made up of polymer plastic film. When heat is applied, it shrinks tightly over whatever it is covering. Heat can be applied with a handheld heat gun, or the product and film can pass through a heat tunnel on a conveyor.

<span class="mw-page-title-main">Linear actuator</span> Actuator that creates motion in a straight line

A linear actuator is an actuator that creates linear motion, in contrast to the circular motion of a conventional electric motor. Linear actuators are used in machine tools and industrial machinery, in computer peripherals such as disk drives and printers, in valves and dampers, and in many other places where linear motion is required. Hydraulic or pneumatic cylinders inherently produce linear motion. Many other mechanisms are used to generate linear motion from a rotating motor.

<span class="mw-page-title-main">Linear low-density polyethylene</span> Polymer

Linear low-density polyethylene (LLDPE) is a substantially linear polymer (polyethylene), with significant numbers of short branches, commonly made by copolymerization of ethylene with longer-chain olefins. Linear low-density polyethylene differs structurally from conventional low-density polyethylene (LDPE) because of the absence of long chain branching. The linearity of LLDPE results from the different manufacturing processes of LLDPE and LDPE. In general, LLDPE is produced at lower temperatures and pressures by copolymerization of ethylene and such higher alpha-olefins as butene, hexene, or octene. The copolymerization process produces an LLDPE polymer that has a narrower molecular weight distribution than conventional LDPE and in combination with the linear structure, significantly different rheological properties.

A polyolefin is a type of polymer with the general formula (CH2CHR)n where R is an alkyl group. They are usually derived from a small set of simple olefins (alkenes). Dominant in a commercial sense are polyethylene and polypropylene. More specialized polyolefins include polyisobutylene and polymethylpentene. They are all colorless or white oils or solids. Many copolymers are known, such as polybutene, which derives from a mixture of different butene isomers. The name of each polyolefin indicates the olefin from which it is prepared; for example, polyethylene is derived from ethylene, and polymethylpentene is derived from 4-methyl-1-pentene. Polyolefins are not olefins themselves because the double bond of each olefin monomer is opened in order to form the polymer. Monomers having more than one double bond such as butadiene and isoprene yield polymers that contain double bonds (polybutadiene and polyisoprene) and are usually not considered polyolefins. Polyolefins are the foundations of many chemical industries.

<span class="mw-page-title-main">AC motor</span> Electric motor driven by an AC electrical input

An AC motor is an electric motor driven by an alternating current (AC). The AC motor commonly consists of two basic parts, an outside stator having coils supplied with alternating current to produce a rotating magnetic field, and an inside rotor attached to the output shaft producing a second rotating magnetic field. The rotor magnetic field may be produced by permanent magnets, reluctance saliency, or DC or AC electrical windings.

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

A bale wrapper is a farm implement for wrapping bales in plastic, for them to turn into silage.

<span class="mw-page-title-main">Unit load</span> Size of assemblage into which individual items are combined for ease of storage & handling

The term unit load refers to the size of an assemblage into which a number of individual items are combined for ease of storage and handling, for example a pallet load represents a unit load which can be moved easily with a pallet jack or forklift truck, or a container load represents a unit for shipping purposes. A unit load can be packed tightly into a warehouse rack, intermodal container, truck or boxcars, yet can be easily broken apart at a distribution point, usually a distribution center, wholesaler, or retail store for sale to consumers or for use.

<span class="mw-page-title-main">ITW Mima Packaging Systems</span>

ITW Mima Packaging Systems is the European marketing division of ITW's Specialty Systems businesses, manufacturing fully automatic stretch wrapping machines in Finland, semi-automatic and automatic machines in Bulgaria and manufacturing film in Belgium and Ireland.

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.

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

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.

<span class="mw-page-title-main">Packaging machinery</span> Any machine used for packaging

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