When Does a Web Scratch Count as a Machine Defect
If a scratch runs across multiple images and the same scratch is not on the edge of the blank film, it was made after entering the machine and counts as a machine defect. If the same scratch is on both the blank edge and the images, the damage is in the incoming material; do not stop at the printing plate looking for it. A scratch that breaks a barcode or fine text must not be shipped, regardless of its source.
A scratch runs across multiple patterns, and there is no identical mark on the blank film edge. This means it was scratched after entering the machine, so it counts as a machine defect. If the blank edge and the pattern have the same scratch, the damage is on the incoming material; don't keep looking at the printing plate. A scratch that breaks a barcode or fine text must not be shipped, regardless of its source.
Where does it start?
Scratches on the machine usually start from a roller, a guide, or a particle of dried ink, so the mark is continuous and runs along the web direction. You can compare film that has not entered printing with film that has been printed: if the mark appears only after the printing point, the source is in the printing unit or a later roller. If it is already there when unwinding, the source is the incoming material or the unwinder itself.
A "line" caused by the printing plate generally repeats at the plate circumference and will not run continuously through the entire roll without repeating. A fine line that does not repeat and is always present is not plate damage.
Whose fault is it?
| Blank edge | Direction of the mark | Attribution |
|---|---|---|
| No such mark | Appears only after the printing point, and does not repeat at the plate circumference | Machine |
| Has the same mark | Already present at unwinding | Incoming material or unwinder |
| Regardless of whether it is present | Breaks a barcode or fine text | This section cannot be shipped |
Do this first this round
- First check the blank film at the unwinder, not the printing plate.
- If it appears only after printing, look along the rollers for protrusions or dried ink. Once found, clean it off and see whether the line stops.
- If a barcode is cut through, mark this section as waste, even if the line later disappears.
