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Cast vs Blown Stretch Wrap

What are the Differences Between Cast Stretch Wrap and Blown Stretch Wrap?

The primary difference between these two types of Stretch Wrap Film is the process in which they are created and manufactured. These differences also make a big impact on the usability and price of the film.

Creation of Cast Stretch Wrap

The cast process is essentially the same as blown, with beads of resin being fed into a heated barrel and forced through a narrow slotted die. This 'sheet' of film the die produced is then fed along a rolling path that has been cooled, which solidifies the film. It is then brought through the final stages of production and made into large rolls. This method is much faster than the blown extrusion method and also costs less, as more can be produced per man-hour. Machine stretch wrap is the most common type of film produced by this method.

Creation of Blown Stretch Wrap

Beads of resin are fed through a heated machine that has a circular die. The heated resin is forced through the die and then blown out vertically into a bubble. As this formed bubble finishes the process of being transformed into rolls of stretch film, it is cooled by the surrounding air. This type of film generally costs more to make because the output per hour is less than with cast films. Our blown hand stretch film is a common example of this type of film. It has a much higher rating than our cast hand film for holding power and puncture resistance.

7 Point Comparison Chart

  Blown Stretch Film Cast Stretch Film
LOAD RETENTION

More holding power, won't re-stretch once applied

Stretches easily, even after applied to pallet which can cause shifting

FILM MEMORY

Higher ability to shrink back to original size after stretch

Minimal ability to go back to original state after stretching

FILM YIELD

Stretches much farther to cover more pallets with less film

Additional stretching can be obtained easier through lower micron blown films (Conversion Chart)

PUNCTURE RESISTANCE

Manufacturing process allows greater resistance to breaking

Standard tearing can occur when stressed too much

CLING OF THE FILM

1 sided cling, great for higher load retention

Naturally clingy on both sides, can make pallets stick together

VISUAL CLARITY

Not crystal clear, can make reading and scanning harder, but has a lower gloss reducing reflections

Perfectly clear, makes reading and scanning in warehouse light easy, but a higher gloss makes reflections annoying.

NOISE OF UNWIND

Loud when releasing from the roll

Very quiet when unwound from the stretch roll

That's a Wrap!

Rocket Industrial offers a variety of stretch wrap options. If you have questions on the best type of stretch wrap to use for your application, contact our packaging specialists. We will find the optimal packaging solution for you based on your needs and goals.

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