When Is Edge Waviness a Printing Problem Rather Than a Die-Cutting Problem
If the material edge is already wavy before die-cutting, it is a printing or web-handling problem, most likely tension, moisture, or drying. If the edge is straight before die-cutting and only becomes wavy after cutting, then it is a die-cutting or knife-pressure issue. Do not wait until after cutting to judge, otherwise both causes will be mixed on one edge.
Before die-cutting, if the material edge is already wavy, this is a printing or web-handling issue, most likely tension, moisture, or drying. If the edge is straight before die-cutting and only becomes wavy after cutting, then it is die-cutting or die pressure. Don’t wait until after cutting to judge, otherwise the two causes will be mixed on one edge.
At which stage it appears
Take a sample before die-cutting. If the edge is already wavy, the die merely cuts along that wave, and the edge of the cut labels will of course also be wavy. If you shim the die at this point, the wave will still be there. The cause lies in the preceding tension, the oven drying one side, or uneven moisture in the paper.
If the edge is straight before die-cutting and only the edge of the individual cut labels becomes wavy, look at die pressure, the anvil roller, and rewind tension. If rewind tension is too high, it can also pull an originally straight edge into a wave; that is still not a defect in the printed graphics, but don’t attribute it to the die either.
Which stage to assign it to
| Edge before die-cutting | Edge after cutting | Assign to |
|---|---|---|
| Already wavy | Also wavy | Tension, drying, moisture |
| Straight | Wavy | Die-cutting or post-cut rewinding |
| Wrinkles in printed graphics, edge also wrinkled | Wrinkles follow | Web-handling wrinkles, not the die |
Do this first this round
- Take samples before the die, don’t only look at finished labels.
- If it is already wavy before the die, adjust tension and drying first.
- If it is straight before the die, then adjust die pressure and post-cut tension.
