Building an Inspection Plan for Die Castings

The drawing defines what matters. Critical dimensions, tolerances, datums, surface requirements and notes should be translated into inspection items rather than treated as general advice.

If the drawing is ambiguous, the ambiguity should be resolved before the plan is written, because inspection cannot fix an unclear requirement.

• Derive items from the drawing
• Identify critical features
• Confirm the datum strategy
• Resolve ambiguity before production

Each item needs a method and a frequency: CMM, gauge, visual, functional test or material certificate. The method should match the tolerance and the risk.

Frequency can range from first-article and periodic checks to 100 percent inspection for safety or sealing critical features.

• Match method to tolerance
• Set frequency by risk
• Use first-article for release
• Reserve 100 percent for critical items

Functional checks can include leak testing, torque, fit or assembly trials. Appearance should be checked against an approved sample under agreed lighting.

Both need written acceptance criteria, otherwise the decision depends on who is looking at the part.

• Define functional tests
• Approve appearance samples
• Agree lighting and viewing distance
• Write acceptance criteria

Records should show what was checked, the result, the lot and the date. They are the evidence used in a customer review or a field investigation.

The plan should also state what happens when a result is out of specification: containment, disposition, root cause and corrective action.

• Keep traceable inspection records
• Link results to lots
• Define containment and disposition
• Close the loop with corrective action