Finished Shrink Wrap Problems: Dog Ears And Triangles

Effect: Dog ears is the 'industry' term for those suppressed triangles at the corner of the shrink film packaging. While it is common place to have small dog ears, the end finish of excessive triangles can be reduced by further sampling.

Shrink wrapping machines utilise two methods to shrink the film by creating a vacuum and at the same time applying heat. This channel of heated air can be tested and modified across your entire product range. Often requiring different settings for each item.

That said, the problem of dog ears cannot always be eradicated but lessened. There are several reasons why your packaging is seeing dog ears in the finished product and ways to reduce the effect once problem ascertained.

  1. Testing with different heat temperatures in the tunnel or chamber will allow you to lessen the effects of dog ears. If your machine suddenly starts delivering dog eared packaging and altering heat settings doesn't resolve, a part may be malfunctioning.
     
  2. The type of shrink film that you use with your machine might be the wrong size or thickness. This might leave too much film around the edges leaving the film with the only option but to fold down on itself once heat is applied. The quality of the shrink film may also be problematic. For instance PVC is of a lesser quality than Polyolefin. Change rolls and experiment.
     
  3. Shrink filming is not an exact science or rather the science as yet can't be fully solved by a machine application. Cardboard boxes have edges and are uniform. Shrink film on the other hand is a not so precise result from heat exchange. The way the heat travels around a product's shape within a vacuum determines how the shrink wrap will collapse in on itself.
     

To labour the final point in layman's terms. If your product is square or rectangular and has obvious edges then the circulation of heat easily shrinks the film to the edges. Where that edge might be circular the film has nowhere to go but shrink to it's opposite film. Hence the triangular shape.

From a design aspect and final packaging, if you have OCD then this could be a huge problem. However most in the industry accept that these dog ears will play a small part in the end product's packaging occasionally. 

Large dog ears and triangles can certainly be combated by testing with different shrink film, heat settings, keeping the machine well maintained on a service contract and using less rounded edges on exterior product packaging.


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