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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.
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.
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 are devices used to apply stretch wrap. There are many types of stretch wrappers:
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.
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.
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.
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.
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.
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.
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.
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.
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.
An automated guided vehicle (AGV), different from an autonomous mobile robot (AMR), is a portable robot that follows along marked long lines or wires on the floor, or uses radio waves, vision cameras, magnets, or lasers for navigation. They are most often used in industrial applications to transport heavy materials around a large industrial building, such as a factory or warehouse. Application of the automatic guided vehicle broadened during the late 20th century.
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.
A bale wrapper is a farm implement for wrapping bales in plastic, for them to turn into silage.
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.
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.
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.
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.
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.
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.