How to decide between on-press inspection and a rewinder camera
On-press inspection stops the press before more bad print. A rewinder camera sorts a roll that is already printed. Choose by the moment the waste is made.
On-press inspection can stop the press before more bad print is made. A rewinder camera sorts after the print is already done. When waste is expensive and the speed is high, choose on-press first. On a short run with very frequent job changes, a rewinder may cost less. They act at different moments. Do not use one in place of the other.
Why it is judged this way
If on-press inspection finds a doctor blade line, the next hundreds of metres need not be printed. A rewinder can only pick those hundreds of metres out, and the paper and ink are already spent. If the defect can be seen only after converting, an on-press camera is of no use either. The inspection point has to move downstream.
What to compare
| What you see | What to call it | What not to do |
|---|---|---|
| The defect appears at printing | On-press is more valuable | Look only at rewind |
| The defect comes from a later process | Put the inspection point at that later process | Buy only a press camera |
| Both are in place | The standard has to be the same | Let rewind use a looser set |
At job change or when a roll is opened
- Write which step produces the most expensive waste.
- Put the inspection point before that step, or at it.
- Do not replace an on-press system that can stop the press with later sorting.
