Review a supplier 8D on three legs: why the defect was made (occurrence), why their checks missed it (detection) and why their system allowed it. A root cause that stops at operator error and retraining has found a person, not a cause. Ask for the next why.
Dunmore's response arrives eleven days after the SCAR, inside the 14 days. It's an 8D report. The root cause reads: "Operator failed to verify thread on the run. Operator retrained."
On time is good. It is also not enough. A response that stops at the operator has found a person, not a cause.
Review it on three legs
Every escape is really three failures, and a good response answers all of them:
- Occurrence. Why did the defect get made?
- Detection. Why did their checks not catch it?
- System. Why did the way they run the plant allow it?
Hold the response up against those three. Dunmore's first answer covered none of them. You wrote back with one question per leg, and the second response was the real one.
The second response named the real causes. The thread-rolling dies had run past their life limit, and the job had moved to a second press without its die counter being reset. In-process checks were first piece and last piece only, so a drift in the middle passed both. Moving a job to another machine was not treated as a process change, so nobody reviewed die life. Each leg now has something you can verify, and each leads to an action: a die-life limit tied to piece count, a periodic check inside the run, and a change notice before any job moves.
What else to check in the response
- Containment. Did they check their own stock and anything in transit, not just your lot?
- Evidence. Does the cause point to something that can be seen, such as a die log, a record or a photo, or is it an opinion?
- Actions. Does each cause have its own action, with an owner and a date?
- Verification. Does the response say how they will know the fix worked?
Push back in writing, and ask a question for each gap. A good supplier will answer. A supplier that cannot answer has told you something too.
The mistake to avoid
Accepting "operator error" or "retrain" as the whole answer. People work inside the system the supplier built. If retraining is the only action, ask the next why: what about the process made the mistake easy? Then ask for that to be fixed.
- Pull the last supplier response you accepted.
- Check whether the cause covers occurrence, detection and system.
- If it stops at retraining, reply this week and ask for the next why.
Open the printable Monday Board
Related on ShopFloorOps
The supplier, the part, the lot and the people in this book (Dunmore Fastener Co., FB-8120, lot 55102) are a made-up example. The tool sidebars show ShopFloorOps tools, which I make and sell. Every chapter teaches the step itself, so you can use your own forms.