Root Cause Analysis of Manufacturing Defects: From Symptoms to Verifiable Causes

The root cause must be able to explain the phenomenon, be repeatedly triggered, and can be eliminated or significantly reduced through measures.

Jinglian Zhongrui Technology Team

Key Points The most common problem in repair sites is mistaking correlation for causation. High-quality analysis first protects the customer and production, then narrows the scope using samples, data, and controlled experiments.

Implementation Focus 1. Clearly define when, where, and what type of defect occurs in which product. 2. Preserve failed samples and original records to prevent evidence from disappearing during repairs. 3. Compare by layers such as material, equipment, method, personnel, measurement, and environment. 4. Confirm the cause and the effectiveness of measures through controlled validation tests.

Verification and Closure Before closing an issue, also check whether adjacent products, similar processes, and control documents need to be updated synchronously.

Project Recommendations During the plan review, input conditions, target values, validation methods, and responsible persons should be recorded in a single traceable document; when changes occur, simultaneously assess the impact on design, manufacturing, and delivery.This approach can transform experience into stable, replicable engineering capabilities. Further reading: ISO 9001 Auditing Practices Group — Measurement Traceability: https://committee.iso.org/files/live/sites/tc176/files/documents/ISO%209001%20Auditing%20Practices%20Group%20docs/Auditing%20to%20ISO%209001%202015/APG-MeasurementTraceability2015.pdf ISO — The Process Approach: https://www.iso.org/iso/iso9001_2015_process_approach.pdf