What is the Unwind Direction
The unwind direction is a critical decision for any printed flexible packaging roll stock application: it tells us in which direction/orientation you want the print to be unwound from the roll when it is on your equipment. If you are hand-packing your food product into Poly Print packaging, then unwind direction may not be such an important consideration in your operation.
Understanding the Unwind Chart
Roll stock can be configured to unwind in 8 different directions (the difference between directions lies in which side of the film the print is on, combined with which direction the print faces, as the roll unwinds), but only 4 print orientations (which direction the print is facing as the roll unwinds) are possible. The Unwind Chart below illustrates this concept: Numbers 1 – 4 show the 4 different print orientations with the print wound out, while numbers 5 - 8 show the same 4 orientations but with the print wound in. For example, the print orientation for 1 and 5 is the same, but these are considered different unwind “directions” since number 1 has the print wound out, while number 5 has the print wound in.
The sealant side (in a multi-layer structure, the layer of film not actually containing print) of the material is another characteristic to consider when determining the appropriate unwind for a given application; to continue the above comparison, numbers 1-4 would indicate sealant wound IN, while numbers 5 – 8 would indicate sealant wound OUT.
Eyespot placement must also be considered if the print includes them, which most food packaging applications do. This eyespot position as it relates to unwind is represented with the letters R (right side), L (left side), B (both sides), and N (no eyespots)
* NOTE: For structures that are laminated without any print, Poly Print simply needs to know if the sealant side is in or out. *
Why does Poly Print have 32 unwind positions?
Choosing the correct unwind position can be confusing; even the most experienced packaging buyers still tend to have trouble with this decision, which if not made correctly prior to printing can be a costly mistake. To help our customers mitigate the risk of making this mistake, Poly Print intuitively created 32 distinct unwinds to represent every possible unwind variation as it relates to print orientation, wind side (in or out), and eyespot position. Under each number you will see the corresponding numbers that are standard for Poly Print as well as industry-accepted; for example: number 9 in Poly Print’s system would be labeled 1L in other industry sectors, as indicated on the chart.
We recommend that customers print the chart out and physically stand at their machine(s) to determine which number corresponds to the way the roll should unwind coming into the former.
If you still have questions about Unwind
If you have questions about determining the proper unwind position for your application, please contact Poly Print or your Poly Print sales representative for support.