Full automation of an L-sealer will allow packs to be automatically fed into the film and through to the sealer.

Manual vs. Automatic

Over the last few years, there has been a general polarisation of the above machines into manual and fully automatic, with relatively few machines being used in semi-automatic form. A manual machine will produce in the order of 10 packs per minute whilst a fully automatic will produce in the order of 20 packs per minute and there is relatively little speed advantage to be gained from a semi-automatic sealer.

Costs also have a significant influence here since entry level equipment can be purchased at significantly less than 2000 pounds whilst fully automatic shrink wrap machinery can be purchased at significantly less than 20,000 pounds.

The conventional use of a manual sealer and tunnel has been significantly reduced by the use of combined seal and shrink machines, commonly referred to as chamber equipment. These machines have a particularly small foot print and operate generally from single phase. The sealer head incorporates a plastic enclosure whilst heat is stored within the unit so that a combined seal and shrink can take place.

The maximum output that can be achieved from a fully automatic sealer will be in the order of 25-35 packs per minute.

As a consequence, both side seal and flow wrap machines are used to offer speeds approaching 100 packs per minute. The methodology remains the same as ever – to wrap the pack in a two dimensional bag of shrink wrap film.

Frequently, flat film is used although folded film is still applied by a number of machines. The sealer will be able to process individual packs at a much higher rate through the ability to seal at an appropriately higher rate.

Cross seals involve the seal device travelling with the pack whilst side seal or overlap seal mechanisms allow for film to be sealed continuously.

These same machines may be applied to other bagging requirements – in particular the mailing of magazines.

Machinery can be specifically customised to take advantage of any shrink wrap film’s particular attributes to allow an appropriate pack to be achieved. One example of the foregoing is the modification of this process to allow for modified atmosphere packaging of food using barrier shrink film.

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