Taping and Ancillary

The Facts On… Heat Sealers

One of the fastest ways to securely pack products in plastic is to heat seal them. The two layers of plastic are clamped together and an electrical current passes through an element (also referred to as a sealing wire) next to them, melting and welding the two films together. When the plastic cools it hardens and the seal becomes as strong as the plastic itself.

The element may be a flat strip of metal, which will create a seal of the same width. If it is a constant heat sealer it may, additionally, be formed with a longitudinally crimped pattern to improve the seal strength and to prevent delamination of laminated materials. Flat elements will only seal the film together, which is why some heat sealers feature an integral film cutter to trim the surplus film off neatly at a fixed distance from the seal.

Round-wire sealers have a narrow element, circular in cross-section. This type of element seals and cuts the film simultaneously to sever the sealed pack from the film reel and create a new sealed edge for the next pack, so it is commonly used on semi-automatic and automatic heat sealing and shrink wrapping systems.

Most systems use what we call impulse heat sealing, where the element rapidly heats up to sealing temperature and electrical current is only applied during the sealing cycle. The benefits of this are that it uses less electricity, prolongs the life of the element (particularly when used sporadically) and reduces the risk of damage or injury in between cycles.

Thicker and laminated films may require a constant heat sealer, which as the name suggests has power continuously flowing through the element. This is necessary to maintain full sealing temperature when heat is lost during the sealing cycle.

The majority of manual and semi-automatic heat sealers only weld a single seam and these are called straight, or I-bar sealers. They may have a clamshell (hinged at one end) or parallel sealing action.

Hand-held heat sealers such as the Pacplus® PHS150 flat sealer and PHS150C crimped sealer are ideal for sealing sacks and other articles too large for a bench sealer.

Treadle-operated constant heat sealers such as the Pacplus CCHS300 and CCHS600 are ideal for small to medium sized bags as the treadle action leaves both hands free to position and hold the bag while a height-adjustable table supports it.

Vacuum heat sealers are sophisticated systems that combine impulse heat sealing with gas flushing and air evacuation for extending the product life of perishables, preventing oxidation, tarnishing and corrosion and creating more compact packages of highly compressible products.

A double, or L-bar sealer features double sealing bars perpendicular to each other, meeting at a corner and a clamshell action with the hinge parallel to one set of sealing bars. These are more commonly seen on semi-automatic and automatic heat sealing and shrink wrapping systems, but can also be used manually to reduce both pack dimensions when sealing in standard-sized bags.

Pacplus® impulse and constant heat sealers are available exclusively through Southgate® and its network of approved distributors throughout the UK and across Europe. They are also exclusive UK distributors for Hacona® C-Type, S-Type and V-Type sealers. For more details call 01553 69 29 69 or email sales@southgate.eu.com.

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