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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 each is created and manufactured. These differences also impact the usability and price of the film.

Creation of Cast Stretch Wrap

A cast extrusion process is used to manufacture cast stretch film. Beads of resin are fed into a heated barrel and forced through a narrow slotted die, creating a 'sheet' of film. The film is then fed along a rolling path that has been cooled, solidifying the film. This process is faster and costs less than the blown extrusion method as more is produced per man-hour. Machine stretch wrap is commonly produced by this method.

Creation of Blown Stretch Wrap

The blown film extrusion process to create blown stretch film is similar to the cast extrusion process. Beads of resin are fed through a heated machine with a circular die, then forced through the die and 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. Hand stretch wrap is often manufactured using this process and typically has higher holding power and puncture resistance.

Which Type of Stretch Wrap is Better?

Choosing the best stretch film is dependent on the wrapping situation. Load retention, film memory, film yield, puncture resistance, cling, visual clarity, and unwind noise are the main factors that need to be assessed before deciding which film is best suited for your situation.

7 Point Comparison Chart

  Cast Stretch Film Blown Stretch Film
LOAD RETENTION

Stretches easily which can cause shifting

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

FILM MEMORY

Minimal shrinking back to original state after stretching

Higher shrinking back to original size after stretching

FILM YIELD

More stretch to wrap more pallets with less film

Less stretch requires more film to wrap pallets

PUNCTURE RESISTANCE

Standard tearing can occur with high stress

Greater resistance to breaking

CLING OF THE FILM

2-sided cling allows pallets to stick together

1-sided cling for higher load retention

VISUAL CLARITY

Perfectly clear, easy scanning and reading, higher gloss creates reflections

Not crystal clear, difficult scanning and reading, low gloss reduces reflections

NOISE OF UNWIND

Very quiet when releasing from the roll

Loud when releasing from the roll

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