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How to Evaluate Stretch Film In Your Plant!

Today we are going to share some practical film tests that you can use in your plant or warehouse to
evaluate how your stretch film is performing. These tests are necessary from time to time as many film
manufacturers still rely on ASTM test data which cannot tell how a film will perform in the real world. As it
is well known that machine settings tend to drift over time, they are also very helpful in giving you a tool to
monitor the effectiveness of your stretch film to make sure that your film and machine are still working
together to give value and performance. I was in a plant recently and was told that the machine was set on
250% pre-stretch. When I checked it, I found that the variable pre-stretch dial had been turned off and
they were not getting any pre-stretch; just running the film through the rollers. Don't let this happen on
your watch.

I will be giving a quick breakdown on these procedures here, but you will be able to download a more
complete description of each test from the Inside Scoop Filing Cabinet located at www.npsinc.net.

The test for Film Pre-stretch on the load is easily done with a
star wheel that puts a mark on the film roll exactly 10" apart
when the film is going through the pre-stretch rollers. Just use
a tape measure to determine the distance between the marks on
the film load after wrapping. If the marks are 35 inches apart,
it means that the original 10 inches of film has stretched to 35
inches on the pallet or 250%. By using this test method on all
films evaluated you can measure the consistency and
effectiveness of the films used.

It is important to measure the holding force of the film or Force
to Load. The procedure is to locate a spot that is 10" in and 10"
down from the edge of the pallet. Use the exact same spot for
all film tested. A round metal plate is placed behind the film and
a scale is attached to the plate. A tape measure is placed
against the pallet though a slit in the film, and the plate is pulled
away from the pallet to 3 inches. At this point a reading is taken
of the pounds of force used to pull the plate 3" from the pallet.
It is important to pull the plate at a consistent rate and angle.
This procedure gives you a holding force to load reading in
pounds.
Snapback represents a visual and numerical reading of the films
ability to retain it's rubber band memory on the pallet. After

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