Two 8D reports described the same defect. One closed in twelve days with a fixture change; the other ran for two months and ended where it started, because step four had been written as a description of the defect rather than as a cause. The eight steps are the same in both; what differs is what each step is required to prove.
8D on a charger: the eight steps and who owns each
Contain, describe, decide the interim action, find the root cause, choose the permanent action, implement it, prevent recurrence, and close the team out.
The first three steps belong to the factory and are time-critical; the middle three need the buyer’s agreement where the product specification is involved; the last two decide whether the report changes anything at all.
The reason to write the steps down is that a defect report is a decision record, not a narrative. Each step has an owner, an output and evidence that it closed, and without those three the report becomes a longer version of the original complaint.
Steps 1 to 3: contain, describe and decide the interim action
The first three steps exist to stop the bleeding while the cause is unknown.
Containment holds the affected lot and notifies anyone already holding units from it. The description states what was measured, on how many units, against which limit, and where in the process it was found. The interim action is what keeps production running without shipping the defect, whether that is a sorting step, an additional check or a temporary limit.
Step 4: root cause, and how to tell it from a restatement
A root cause explains why this unit failed and the one beside it did not.
If the stated cause cannot answer that question, it is a restatement of the defect with a technical word attached. The test is whether a measurement or a reproduction demonstrates it, and whether removing the cause removes the defect. On a charger, the useful causes are specific: a fixture that drifted by a stated amount, a substitution in the power stage, a limit taken from a datasheet, a torque applied outside its range.
Step 5: choosing the permanent corrective action
The permanent action follows from the cause, not from the difficulty of the fix.
Where the cause is a fixture, the fix is a fixture change; where the cause is a limit, the fix is the limit and its source; where the cause is a supplier, the fix is the incoming verification plus the supplier conversation. Where the permanent action is a training session only, the report should say so, because training depends on the person and the shift rather than on the process.
Step 6: implementing it without breaking something else
The implementation is verified before the report is closed.
That means a defined run of units produced under the new condition, measured against the same parameter that identified the defect, with the result recorded. It also means checking the neighbouring parameters: a limit tightened to catch one defect can start rejecting good units, which produces a different problem with the same report number.
Step 7: preventing recurrence, which is where most reports stop
Prevention is a change to the system, not a change to the batch.
It means the fix applies to the next order, to a second product on the same platform, and to the criteria document. Confirm it by asking which documents were updated, because a corrected batch is a correction and only a document change is prevention. Where a similar product exists, the same question is asked of it: does the defect mechanism exist there too.
| Step | Owner | Evidence it closed | Common failure |
|---|---|---|---|
| 1 Containment | Factory quality | Units held and notification issued | A reply without a hold |
| 2 Description | Factory, confirmed by buyer | Measurement, units and limit | A narrative without numbers |
| 3 Interim action | Factory | The additional check in the process | Proceeding with no interim step |
| 4 Root cause | Factory engineering | A measurement or reproduction | A restatement of the defect |
| 5 Permanent action | Factory with buyer agreement | The chosen change and its reason | A fix unrelated to the cause |
| 6 Implementation | Factory | A verified run under the new condition | A change with no verification |
| 7 Prevention | Both | Updated documents and criteria | No document changed |
| 8 Closure | Both | A signed record and a review date | Closing at the first good batch |
Step 8: closing the record, and why the date matters
Closure is a decision with a signature, and it should include a review date.
The review is what confirms the fix held: a defined number of units produced afterwards, measured on the same parameter, with the result attached to the original report. Where closure happens on the first good batch, the report records an improvement rather than a fix, and the same defect often reappears two months later with a new number.
How to read an 8D you receive
Read step four first, then step seven.
Step four tells you whether the cause was found: if it cannot explain why one unit failed and its neighbour did not, the rest of the report is built on a guess. Step seven tells you whether anything will change: if no document, fixture or limit was updated, the defect and the report will both return. The remaining six steps describe how well the process was managed in the meantime.
FAQ
Is an 8D required for every defect?
It is justified where a defect reached a customer, repeated across batches or involved a safety-related parameter. For a defect caught in process, a short record with the cause and the change carries the same information without the eight-step structure. It is justified where a defect reached a customer, repeated across batches or involved a safety-related parameter, while a process defect needs a shorter record.
Who should own the root cause step?
Factory engineering, with the buyer confirming the specification side where the cause touches a limit. A cause owned by the commercial team tends to be a cause that requires the least change rather than the one that explains the data. Factory engineering owns the root cause with the buyer confirming the specification side, because a cause owned by the commercial team requires the least change.
What if the factory says the cause is the buyer’s specification?
That can be the correct answer, and it should be supported by the measurement that shows the specification is outside the design’s capability. The permanent action then becomes a specification change agreed by both, rather than a process change made to compensate silently. That can be the correct answer where the measurement shows the specification is outside the design’s capability, and the permanent action becomes a specification change.
How long should an 8D take?
Containment within days, and the root cause within a couple of weeks for a defect that can be reproduced on demand. A report that runs for months without a demonstrated cause is usually waiting for data that should have been collected at containment. Containment is within days and the root cause within a couple of weeks for a defect that can be reproduced on demand.
Next step
Send the defect, the lot data and the measurements you hold to Wecent Group through the contact page. The reply returns the containment step, the measurement that establishes the cause and the document change that prevents recurrence. Related reading: our charger factory, OEM and ODM charger manufacturing and charger manufacturing services. External references: IEC standards, IEC Webstore, UL standards and certification, TUV testing services, Intertek testing services and IQNet certification network.
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