When a customer, often an automotive or electronics OEM, sends a complaint, the supplier is expected to reply with an 8D report: containment within 24 hours, root cause and corrective action within days, and closure with evidence. Many 8D reports fail the customer's review because the problem statement is vague, the root cause is "operator carelessness" (操作员疏忽), or the corrective action is "strengthen training". This skill writes an 8D that would pass a demanding customer quality engineer.
Write in Simplified Chinese with an English version of each section (customers outside China usually require English), unless asked otherwise. Customer-specific requirements (CSR), for example a required template, response times or IATF 16949 expectations, take precedence; anything assumed is marked to be verified. For analysing a batch of field returns across failure modes, use rma-failure-analysis; this skill is for one problem, written up for a customer.
Required Inputs
Ask for these if not provided, otherwise infer and label the assumption:
- The complaint: customer, part number, defect description, quantity, where and when found, photos or measurements, the customer's deadline and template
- Production facts: lot or date codes, process flow, line, shift, equipment, materials and suppliers involved
- What is known so far: containment done, inspection results of stock (in the plant, in transit, at the customer), any changes (4M: manpower, machines, materials, methods, plus environment and measurement) around the time
- Analysis done: tests, comparisons of good and bad parts, reproduction attempts
- Team: names and roles
Output Structure
D0 Preparation
Whether an emergency response is needed, and the decision to open an 8D.
D1 Team
| Name | Department | Role | Name, department, role | A champion, a leader, and members from quality, production, engineering and, where relevant, the supplier.
D2 Problem description (5W2H)
What, where, when, who found it, why it is a problem, how it was found, how many; with the specification versus actual and photos referenced. One clear problem statement.
D3 Containment (dated)
| Location | Quantity | Inspection method | Result | Owner | Completion date | Suspect stock at the customer, in transit, in the warehouse and in WIP; sorting method; how good parts are marked (for example a clean-point label from a stated date or lot); the effectiveness check.
D4 Root cause
Two causes, each with evidence:
- Occurrence root cause: why the defect was made
- Escape root cause: why it was not detected Use a fishbone (manpower, machines, materials, methods, environment and measurement) to list candidates and 5 Why to drill down, with each step backed by data; label each cause "verified" (for example by reproducing the defect) or "hypothesis". "Operator error" is not accepted as a root cause without asking why the process allowed it.
D5 Permanent corrective actions
For each root cause, the chosen action, why it addresses the cause, and how it was verified before full implementation. Prefer error-proofing (poka-yoke) and design or process changes over training and inspection.
D6 Implementation and validation
| Action | Owner | Completion date | Verification method | Result | Cut-in point (date, lot or serial), and data showing the defect has stopped.
D7 Prevent recurrence
Updated documents: PFMEA, control plan, SOP (see cn-sop-writer), inspection standards, and lessons applied to similar parts and lines (horizontal deployment).
D8 Closure
Closure criteria (for example no recurrence over three months or a set number of lots), team recognition, and the customer's sign-off.
Quality Checks
- The D2 statement is specific: part, defect, quantity, specification versus actual
- Containment covers every location of suspect stock, with quantities and dates
- Both occurrence and escape root causes are given, with evidence and verified or hypothesis labels
- Corrective actions address the root causes and favour error-proofing over training
- PFMEA, control plan and SOP updates are named in D7
- Chinese and English versions match, and customer-specific requirements are noted
Anti-Patterns
- "employee carelessness" as root cause. Ask why the process let a person make or miss the error.
- "strengthen training" as the corrective action. Training fades; change the process or add error-proofing.
- Containment without quantities. The customer wants to know exactly how much stock was checked.
- One root cause only. Without the escape cause, the next defect will also reach the customer.
- Closing without data. Show the defect has stopped.
Example Trigger Phrases
- "The customer complained about sink marks on our injection-moulded parts, a batch of 2,000 units, and wants an 8D response within three days. Help me write it."
- "The customer rejected our 8D because the root cause said operator carelessness. How should we change it?"
- "Help me turn this customer complaint into a Chinese and English 8D report."
- "What should D3 containment include?"
- "Write an 8D report for a customer complaint about a dimension defect."