What Counts as Unacceptable for a Flexo Missing-Print Void
A flexo void is a gap with no ink at all in a solid area, text, or barcode. If it breaks through a drug name, fine text, or barcode, stop the press; if it only lands in a large solid area and its diameter is no larger than the customer's dirt spec, release it as a dirt defect, and do not scrap the whole roll.
A flexo void is a gap in a solid, text, or barcode where there is no ink at all. If it punches through a drug name, fine print, or barcode, stop the press; if it falls only in a large solid area and its diameter is no larger than the customer's dirt speck chart, pass it as a dirt speck—do not scrap the whole roll.
How to distinguish it from a dirt speck
There are no particles in the center of a void. A dirt speck is ink skin, paper fuzz, or dried ink particles blocking transfer, and it often has a ring of squeezed-out ink around it; a void has no ink at all in that spot, and under magnification its edge breaks off abruptly along the solid, exposing the substrate color.
In the same roll, if the spacing of the voids equals the plate cylinder circumference, first check the printing plate and double-sided tape. If it persists after changing the plate and appears across the whole plate, then check anilox roll clogging and ink viscosity. Do not scrap the whole roll as soon as you see a white spot, and do not let a barcode pass just because the white spot is small.
Stop or pass
| Location | How to judge | Action |
|---|---|---|
| Barcode, drug name, regulatory text | Stroke or bar is punched through | Stop the press; scrap this section |
| Large solid area, not over critical information | Not larger than the diameter on the customer's dirt speck chart | Pass as a dirt speck and retain a sample |
| No dirt speck chart on the work order | No limit to compare against | Stop and ask; do not pass it yourself |
Do this first this round
- Use a magnifier to check whether there are particles in the center of the void. If there are particles, it is a dirt speck; investigate it as a dirt speck, and do not wash the plate as if it were a missing print.
- Measure the distance from this spot to the next; compare it with the circumference of the plate cylinder, anilox roll, and guide rolls.
- First confirm whether it punches through barcodes and text; only then discuss whether the diameter is large enough.
