Bottled Zamzam water - Flickr - Al Jazeera English

A shrink tunnel or heat tunnel is a heated tunnel mounted over or around a

conveyor system A conveyor system is a common piece of mechanical handling equipment that moves materials from one location to another. Conveyors are especially useful in applications involving the transport of heavy or bulky materials. Conveyor systems allow ...

. Items (such as

packaging Packaging is the science, art and technology of enclosing or protecting products for distribution, storage, sale, and use. Packaging also refers to the process of designing, evaluating, and producing packages. Packaging can be described as a c ...

) have

shrink film Shrink may refer to: Common meanings * Miniaturization *Shrink, a slang term for: ** a psychiatrist ** a psychoanalyst ** a psychologist Arts, entertainment, and media * ''Shrink'' (album), album by German indie rock/electronica group The Notw ...

loosely applied; with heat, the film shrinks to fit snugly around the wrapped object.

Uses

* Shrink

label A label (as distinct from signage) is a piece of paper, plastic film, cloth, metal, or other material affixed to a container or product, on which is written or printed information or symbols about the product or item. Information printed ...

s. * Combining small items for sale and display (example: bottled water). * Tamper resistant or

Tamper-evident band A tamper-evident band or security ring serves as a tamper resistant or tamper evident function to a screw cap, lid, or closure. The term ''tamper-proof'' is sometimes used but is considered a misnomer given that pilfering is still technic ...

s or seals. * Form large

unit load 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 fork ...

s for transport. * Form primary barrier on foods such as cheese, meats and fish. *

Skin pack Skin pack, or skin packaging, is a type of carded packaging where a product (or products) is placed on a piece of paperboard or in trays, and a thin sheet of transparent plastic is placed over the product and paperboard or trays. The printed paperb ...

Types

Several types of shrink tunnels are available. The heat source can be based on

heating element A heating element converts electrical energy into heat through the process of Joule heating. Electric current through the element encounters resistance, resulting in heating of the element. Unlike the Peltier effect, this process is indepen ...

(electrical resistance),

infrared heater An infrared heater or heat lamp is a body with a higher temperature which transfers energy to a body with a lower temperature through electromagnetic radiation. Depending on the temperature of the emitting body, the wavelength of the peak of the i ...

, steam, or gas flame. Often forced air is used to improve

convection Convection is single or multiphase fluid flow that occurs spontaneously due to the combined effects of material property heterogeneity and body forces on a fluid, most commonly density and gravity (see buoyancy). When the cause of the c ...

, sometimes focusing the heat on one component of the item. Tunnels are available with or without a conveyor system. Some are built into a production line or are integral with machinery that also applies the shrink film. Others are movable by hand or by castors. A shrink tunnel, referred to as an oven, may be equipped with an integrated conveyor of two different kinds: the roller conveyor or the

belt conveyor A conveyor belt is the carrying medium of a belt conveyor system (often shortened to belt conveyor). A belt conveyor system is one of many types of conveyor systems. A belt conveyor system consists of two or more Conveyor pulley, pulleys (somet ...

. Roller conveyors can be used with

polyolefin 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 speciali ...

, PVC, and shrink

polyethylene Polyethylene or polythene (abbreviated PE; IUPAC name polyethene or poly(methylene)) is the most commonly produced plastic. It is a polymer, primarily used for packaging ( plastic bags, plastic films, geomembranes and containers including b ...

films. The space in between the rollers is filled with hot air from the bottom of the tunnel to shrink the film layer around the object, creating a sealed package. When used with polyolefin and PVC based films the rollers are called "live" or spinning. When used with polyethylene films the rollers are called "dead" or not spinning. The tunnels with

Teflon Polytetrafluoroethylene (PTFE) is a synthetic fluoropolymer of tetrafluoroethylene that has numerous applications. It is one of the best-known and widely applied PFAS. The commonly known brand name of PTFE-based composition is Teflon by Chemo ...

mesh belts and

polymer A polymer (; Greek '' poly-'', "many" + '' -mer'', "part") is a substance or material consisting of very large molecules called macromolecules, composed of many repeating subunits. Due to their broad spectrum of properties, both synthetic a ...

mesh belts are used for smaller packages, or when the package may have an instability and need a stable platform. Some heat shrink tunnels have two or more zones for heating and controlled cooling.

References

* Soroka, W, "Fundamentals of Packaging Technology", IoPP, 2002, * Yam, K. L., "Encyclopedia of Packaging Technology", John Wiley & Sons, 2009,

External links

More information about shrink tunnelsExample of Steam Tunnel & Shrink Sleeve Applicators
{{DEFAULTSORT:Shrink Tunnel Packaging machinery Plastics applications Industrial ovens

Uses

Types

See also

References

External links