Before you start calling heat tunnel suppliers there are a few things you should know about your process:
These are all questions a reputable equipment supplier should be asking when you approach them. Having the answers at your fingertips will make your interactions with them more efficient.
No two shrink applications are the same. To ensure that they achieve a perfect, repeatable shrink of sleeve labels, your equipment supplier should ask for samples to conduct tests. Two of the primary variables they will test for are Temperature and Time.
Temperature versus Time
One of the advantages of using a hot air based system for shrinking is the flexibility it offers. The operating temperature can be adjusted through a wide range of set point temperatures which provides increased flexibility. This offers another variable that can be altered to compensate for increasing line speeds, beyond simply extending the length of the shrink tunnel.
Heating time, or residence time, is related to the physical length of the tunnel and the speed with which the bottle moves through the tunnel. Increasing the residence time can increase the degree of shrink (similarly to increasing temperature). However, increasing residence time and increasing temperature will not always yield the same result and should not be considered perfect substitutes for one-another.
The best temperature setting depends on a number of factors:
If your temperature is too low, there is potential for incomplete shrink. If your temperature is too high, there is potential for label damage such as splitting. Higher temperatures can allow for increased line speeds – although there are limits. Higher temperatures can also enable shorter heat tunnels.
This is a simplistic review of heat shrinking and there are many more variables that come into play when designing a quality heat shrink system.
Want to discuss your application? Our Technical Sales Representatives are more than happy to review the specifics of your heat shrink needs.
Need some help testing? Our Application Engineer can test your packaging and recommend custom or off the shelf heat shrink equipment (including recommended operating parameters) that will best suit your needs.