D5 — D5: Verifying Corrective Actions with Data

Part of the 8D methodology (D0–D8).

Discipline 5 (D5) is the "before-the-fact" validation phase. Before you commit to a permanent change in tooling, software, or design, you must prove that the proposed solution actually works and doesn't introduce "Side Effects."

How Many Batches Prove a Fix Works? The team should evaluate multiple options. The ideal PCA is: - Fail-Safe (Poka-Yoke): Makes it physically impossible for the error to occur. - Robust: Works across all shifts, operators, and environmental conditions. - Cost-Effective: Balanced against the risk of the defect.

What’s a Side-Effect Analysis? - DOE (Design of Experiments): Testing the new process parameters. - Pilot Runs: Producing a small batch under "Gold Standard" conditions. - Simulation: Using software to predict the fatigue or stress performance of a new design.

Should You Remove Containment Before Verification? Every change has a consequence. If you increase the hardness of a material to prevent wear (PCA), does it make the part too brittle for low-temperature environments? D5 must explicitly document these "What-If" scenarios.