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What is the Difference between Blown & Cast Stretch Film?

by Jim Stalker March 09, 2020

What is the Difference between Blown & Cast Stretch Film?

There are two types of stretch film -  blown and cast.  Both types have specific characteristics that create unique benefits depending on the application.

Blown Stretch Wrap is made from beads of resin that 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 the formed bubble finishes the process of being made into rolls of stretch film it is cooled by air.  This type of film usually will cost more because it is more labor intensive.

Cast Stretch Wrap is made from beads of resin being fed into a heated barrel and being forced through a narrow slotted die.  This “sheet” of film the die produced is the fed along a rolling path that has been cooled which makes the film solid.  The film is then brought through its final stages of production and made into rolls.  This method is much quicker and less labor intensive making is less expensive to the customer. 

 

Blown Stretch Film

Cast Stretch Film

1). Load Retention:

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

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

2). Film Memory:

Higher ability to shrink back to original size after stretch

Minimal ability to go back to original state after stretching

3). Film Yield:

Stretches much farther to cover more pallets with less film

Additional stretching can be obtained easier through lower micron blown films

4). Puncture Resistance:

Manufacturing process allows greater resistance to breaking

Standard tearing can occur when stressed too much

5). Cling of the Film:

1 sided cling, great for higher load retention

Naturally clingy on both sides, can make pallets stick together

6). 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.

7). Noise on unwind:

Loud when releasing from the roll

Very quiet when unwound from the stretch roll

 

Jim Stalker
Jim Stalker


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