A repeat defect usually means the last corrective action treated a symptom. Pull the previous 8D or corrective action, check whether the root cause was ever verified, dig again with 5-Why and a fishbone, choose a fix that changes the process rather than the person, and prove it held with an effectiveness check.
Start with
Pull the last fix and ask why it did not hold.
The path, in order
Review the last fix
Read the previous corrective action. Was the root cause verified by turning it on and off, or only stated? Was the action "retrain the operator" or "remind the team"? Those are the most common reasons a fix does not hold.
5-Why
Ask why the defect occurred and, separately, why it was not detected. Keep going until you reach a cause you can control and verify.
Fishbone
Check the categories you skipped last time: method, machine, material, measurement, people and environment. Repeat defects often hide in measurement or material.
Corrective action
Prefer error-proofing and process changes over inspection and training. Update the work instruction and the Control Plan to match.
Effectiveness check
Decide up front what proves it worked, such as zero occurrences over a set number of lots, then check on schedule before you close it.
Use these next
- Containment, correction and root cause
- How to write an 8D report
- Free 8D starter form
- ShopFloorOps workbooks on Etsy: The Root Cause & Corrective Action Bundle on Etsy includes the root cause tools and an effectiveness tracker.