Shrink Temperatures for Centerfold Shrink Film
The temperature a shrink film begins to shrink is important for many reasons. Primarily to be sure the product being wrapped will not be damaged by the temperature necessary to shrink the film. In addition, knowing approximate temperatures will help set machines properly for each material and thickness being used.
In this test, we used PVC and Polyolefin shrink film through a tunnel with a total dwell time of 8 seconds. Beginning at 180 degrees Fahrenheit, up to 350 degrees all materials and thicknesses were tested. The finished product was rated using five options from no-shrink through too much shrink indicated by burn holes and melted shrink film.
The Grading Scale
None indicates the shrink material did not begin to shrink at the tested temperature. A poor shrink rate indicates the material began to shrink, but still has excessive wrinkles and is not conformed to the product.
A fair or good shrink rate is the next two options used in the test. A fair shrink rate shows the material conforming to the product with wrinkles on the edges. A good shrink rate fits tightly around the product with minimal wrinkles around the edges.
Too much shrink indicates burn holes or melting.
The lowest shrink temperature tested was 180 degrees Fahrenheit in which the centerfold PVC shrink film was the only material that experienced a fair amount of shrink. All of the other shrink films showed poor shrink rates at that temperature with an 8-second shrink tunnel dwell time. Some of the heaver polyolefin and crosslinked polyolefin shrink film displayed no shrinking at the lowest temperature tested.
For the highest temperature tested, which was 350 degrees Fahrenheit, only two materials did not have burn holes. Both of the materials graded as good at 350 degrees were a 100 ga thickness. Thicker shrink film requires higher temperatures or longer heat exposure to shrink the material.
The temperature that performed best for centerfold shrink film was 300 degrees Fahrenheit. More materials and thicknesses exhibited a good shrink rate at this temperature than any other. Keep in mind the time the package is in the tunnel has an impact on the shrink rate of the material.
An example of this was at the end of this test. At 350 degrees and an 8 second shrink tunnel dwell time, the PVC shrink film burned through and melted. When we sped up the conveyor and only had a 2 second tunnel dwell time the PVC shrink film looked perfect coming out of the shrink tunnel. Speeding up the tunnel allows you to run products faster at a higher temperature.
If you need assistance with shrink film shrink rates or heat tunnels, call 1-800-441-5090. A sales associate will help with your specific packaging needs.