What to review before you loosen a dirt-spot threshold
Rule out a dirty lens and a wrong template first. Texture is zoned, not loosened across the whole web. Keep the old threshold.
Before you loosen a dirt-spot threshold, look at three things: whether the lens is dirty, whether the wrong template is in use, and whether the material texture should be zoned instead of loosening the whole web. After all three are ruled out, quality changes the threshold and keeps the old value. An operator cannot loosen it alone.
Why it is judged this way
Once the threshold is loose, real defects and false alarms disappear together, and the report looks clean. So changing the threshold belongs to quality, and the reason is written. The next day, run a known-defect sample once and see that what should alarm still alarms.
What to compare
| What you see | What to call it | What not to do |
|---|---|---|
| The lens and the template have both been checked | Only then can loosening be discussed | Loosen as soon as alarms pile up |
| False alarms only in the texture zone | Loosen only that zone | Loosen the whole web |
| After the change, no retest on a defect sample | It is not finished | Go straight into production |
At job change or when a roll is opened
- Wipe the lens first and check the template version.
- If it can be zoned, leave the setting for the whole web.
- After the change, run the known-defect sample once more.
