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Summary

As an addition to the manual, this article will provide a little bit more detail about the Material Settings in the Studio toolkit for Shrink Sleeves.

Symptoms

In case you don't know where to find the Material Settings for a specific material or if you don't know which value to input and where, then the below information might be of help.

Solution

About material shrink characteristics:

The first two values in the Material Shrinkage section of Toolkit for Shrink Sleeves represent the maximum unconstrained shrink in machine direction and transverse direction.

The Friction is the ratio of the force of friction and the force pressing the sleeve onto the surface. The higher the value of the friction coefficient, the more difficult it will be for the sleeve to slide over the surface of the package in areas where there is tight contact.

Typical PET shrink film has a low shrink value in the machine direction and a high value in transverse direction. This is represented in the default values (10% and 70%).

Some questions you might have:

  1. What is unconstrained shrink?

  2. What is machine direction?

  3. What is transverse direction?

  4. What is the friction range we can use?

  1. Unconstrained Shrink: Shrink that is free from any constraints, i.e., not subject to friction or to irregular shapes etc.,
    About the Material Settings:
    1. Normally, a list of materials are already implemented, so there are no percentage values but only a drop-down list of e.g. PET, PVC etc., Because all these materials have their own fixed shrink values, we know how these materials will behave when shrinking them in the heat tunnel.
    2. For the current version, we’ve chosen to display the percentage values so that customers can still tweak it a little bit if the result isn’t quite what they expected. So, materials like PET have their own characteristics regarding shrinking: PET will shrink vertically about 4% while it will shrink about 54% horizontally. Attached is a screenshot in which you can see a normal un-shrunk PET square and a shrunk PET rectangle. If you measure the difference after shrinking, you get the percentage values that you need to fill in.

    3. It’s really important to use the right shrink values. If they are not known, then it is relatively simple to do the free-shrink-test yourself. In case you are looking for any kind of document that gives you settings suggested for different types of materials, there are two ways to get that information:
      1. You can obtain the technical sheet from the shrink film manufacturer. These sheets typically mention MD and TD shrink (or sometimes plotted in a graph for different tunnel temperatures).
      2. Or you can perform a shrink test yourself:
          1. Cut a few squares of 10 cm x 10 cm of the sleeve material. Mark it, so that you can still distinguish MD (winding direction) from TD.
          2. Put them in (nearly) boiling water for 10 seconds, remove and measure the new depth & width. E.g.: If it measures 9.4cm x 4.5cm then the shrink values are 6% and 55%.
  2. Machine and transverse direction: The meaning of the // shrink value in the Studio Toolkit for Shrink Sleeves user interface is the maximum possible amount of shrink of the film measured in the film direction parallel to the axis of the sleeve. The _|_ value is the film's maximum shrink value along the circumference of the sleeve.
    In our opinion, there is no prior correspondence between TD and MD on the one hand, and the // and _|_ symbols in the Studio Toolkit for Shrink Sleeves on the other. Either TD is // and MD is _|_, or the other way around, depending on which of two possible ways the sheet of film is turned into a sleeve (tube). Which way this is done, depends on the desired shrink properties of the sleeve.
    1. For vertical shrink sleeves (first sealed then placed over object) the first number corresponds to MD and the second number corresponds to TD.
    2. For horizontal shrink sleeves and “ROSO” labels (first wrapped around object, then sealed), the first number corresponds to TD and the second number corresponds to MD.
    In general, you’ll find that the first number is typically the lower value and the second number is typically the higher value.
  3. Friction range: Our suggestion is to not change this friction value unless you need some special feature like a “Smiley down effect at the bottom of flat bottles” or a “creeping up of the sleeve material around the neck of a shampoo bottle”.

    The range would go from 0 to 1 but it's best not to go outside the values 0.1 to 0.6, so rather make small changes like 0.25 to 0.45.

 

 

Article information
Applies toStudio Toolkit for Shrink Sleeves all versions
Created17-Jul-13
Last revised17-Jul-13
AuthorSDME
CW Number 
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