Stretch Film: Cast vs. Blown. Which should I use?

By |2018-01-22T08:08:59+00:00January 22nd, 2018|Packaging Supplies|0 Comments

Stretch film is probably the most widely used packaging product in the industrial market.  It is a stretchable packaging film that is used to wrap goods – oftentimes, referred to us bundling or unitizing. If you’re palletizing products for shipment, then you’re almost certainly using stretch film to help secure the load.

There are two types of stretch films that you may have heard of:  cast stretch film and blown stretch film.

Blown Stretch Film.  What is it?

Blown stretch film is manufactured in a machine, called an extruder, that has a circular die in it.  Beads of resin are pushed through the machine and heated, which causes them to bubble.  The bubble is then cooled by the surrounding air, and the product remaining is transformed to rolls.

Blown stretch film, sometimes referred to as blown stretch wrap, is a bit more pricey due to its manufacturing process, however, it carries with it a higher puncture resistance.

Here are some of the main characteristics of a blown stretch film:

  • Load Retention:  Blown stretch film has more holding power, meaning that it keeps its original tension around the product.
  • Film memory –  Blown film has a higher ability to shrink back to original size after it is stretched.
  • Film yield – Film yield refers to its ability to stretch much farther to cover more pallets with less film
  • Puncture resistance – The manufacturing process allows this packaging wrap greater resistance to breaking
  • Cling to the Film – Blown stretch wrap has double sided cling.
  • Visual Clarity – It is not crystal clear.
  • Noise on Unwind – This type of film is loud when releasing from the roll

Cast Stretch Film.  What is it?  How is it different?

Cast stretch film is manufactured using a process called cast extrusion.  In this process, the resin is melted and then pushed through a flat die onto a chill roll where it is resolidified.   The great thing about cast films is that their manufacturing process allows the films to a high percentage of stretch and uniform gauge.

There are both machine grade and hand grade cast stretch films available.

Some of the key characteristics of a cast stretch film include:

  • Load Retention:  Cast stretch film stretches easily.
  • Film Memory:  Minimal ability to go back to original state after stretching
  • Puncture Resistance:  Increased tear and puncture resistance
  • Cling of the Film:  Superior one-side cling
  • Visual Clarity:  Cast film is perfectly clear and can be identified by its high gloss.
  • Noise on unwind:  This type of film is very quiet when unwound from the stretch roll.

At Axis Packaging we supply both hand and machine cast stretch films and blown stretch films. And it’s also available online at stretchsource.com.

Choosing the correct stretch film is a decision that should be made based on a proper packaging assessment, with a packaging company that has the knowledge to implement a solution that you can depend on. At the end of the day, every load is different and our product specialists are here to help you pick the correct film.

Call us today at 877-410-5564 to speak with a product specialist about your stretch film needs.

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