First steps
- Contain: stock, in transit, at the customer.
- Reproduce the defect and verify the root cause.
- Close only after the effectiveness check.
How to measure success
Customer PPM, 8D lead time and repeat complaints. Record the value before you start, so the effect of every action can be shown.
When these methods are the wrong choice
- 8D report: Small internal issues where one person can fix the cause in a day.
- 5 Why: Problems with many interacting causes; use data and DOE there.
- Ishikawa (fishbone): Proving a cause; it only lists candidates to verify.
- CAPA / NCR tracker: Analysing one problem in depth.
- PFMEA / DFMEA: Fixing a problem that has already happened; update it after the 8D instead.
- Control plan: Nothing in series production: every IATF process needs one.
- Layered process audit (LPA): Finding root causes.
The methods in one line
| Method | What it is |
|---|---|
| 8D report | Team-based method for customer complaints: containment, root cause for occurrence and non-detection, verified corrective action, prevention. |
| 5 Why | Ask “why” until you reach a cause you can act on, with one chain for occurrence and one for escape. |
| Ishikawa (fishbone) | Structured brainstorm of possible causes by 6M: man, machine, method, material, measurement, environment. |
| CAPA / NCR tracker | Register of nonconformities and corrective actions with owners, deadlines and effectiveness checks. |
| PFMEA / DFMEA | Analyses how a process or design can fail, rates the risk (AP) and defines prevention and detection. |
| Control plan | Lists every characteristic, how it is checked, how often and what the reaction plan is. |
| Layered process audit (LPA) | Short daily checks of key process controls by several management layers. |