Case Histories

Learn more about Cryovac® Performance Shrink Films

Auckland based Thomas Holdsworth has been a CRYOVAC shrink film customer for many years. As a toys and games manufacturer they use shrink film to overwrap flat jigsaws and seal boxed games and puzzles as a tamper evident enclosure.

Over time they have tried a variety of means to expel the air from packs during shrink-wrapping. Many of their packages have a high air to mass ratio meaning that packs need to release air efficiently and reliably or the packs can have a loose appearance after shrink.

In the 80’s and 90’s they had developed a technique of drilling rolls of film with a power drill at regular intervals around its circumference before starting to wrap on manual L-bar sealers but this has its drawbacks. If the drill is blunt or the film is drilled too fast the heat generated can weld layers of film together which in turn initiates tears in the roll. If the rolls are drilled too deep the holes effectively move closer together as the roll is wound down and soon where one hole per pack was OK the customer now has three holes per pack and the shrink effect is ruined.

The supply of CRYOVAC D955P factory preperforated films to Holdsworths and all CRYOVAC customers has alleviated all these problems.

The benefit of a consistent air release is not widely appreciated by film users. When packs enter the shrink tunnel they contain a volume of air that must be expelled in a specific manner. The effect of the tunnel heat is to firstly expand the trapped air and cause the film to "balloon", i.e. blow up into a tight pillow appearance. It is at this point that the film loses wrinkles and creases. As the pack is subjected to further heat the film contracts to fit the product and squeezes the air out via the vent holes.

So to achieve a good finished appearance you need a certain number of perforations with a certain hole size on each pack. Each package needs the same air release, they can be under or over-vented.

Drill holes have the limitations described above.

Hot hole punches, wired to the impulse seal wire to create a hole punch on each cycle, accumulate heat as the run proceeds so that the hole size varies and shrink becomes unsightly.

Pinwheels are a common accessory on shrink equipment but they can become blunt, may not always puncture the film or can snag and tear the film. On manual sealers the effort to unwind the film through a perforator can become a significant strain on the operator.

CRYOVAC can preperforate all its films, plain or printed, and the problem is completely resolved for the customer.

Air escape is consistent regardless of the pack dimensions. Final shrink appearance is tidier and there is virtually no burn through due to excess heating in the tunnel.

There is no hardware like pinwheels or hole punches to maintain and reduced operator intervention is needed to achieve tightly shrunk packs.

The perforations are not at all unsightly and would often be unnoticed by the customer if the film were being shrunk on to a solid surface.

Couple the preperforated format with CRYOVAC D955P proven toughness and seal performance and this film is extremely user friendly with a very wide operating tolerance.

Learn more about Cryovac® Performance Shrink Films