7.4 Layered Process Audits (LPA)

Inspection checks the product; LPAs check the process. A perfect product made by a rogue process is a ticking time bomb. Layered Process Audits (LPA) are the immune system of the factory floor. They are high-frequency, short-duration checks performed by multiple layers of management to enforce standardization and detect "process drift" before it becomes a defect. If the Plant Manager never walks the line, the line assumes quality is optional.

The Physics of "Drift"

Processes naturally degrade. Tools wear, attention wanders, and "tribal knowledge" replaces the SOP. LPAs provide the activation energy required to maintain the steady state.

The Tiered Logic:

Tier 1 (Daily / Shift): Performed by Team Leads.

• Mission: Immediate containment.
• Action: Check the inputs. Is the torque driver calibrated? Is the operator wearing a heel strap? Is the revision on the screen correct?

Tier 2 (Weekly): Performed by Quality/Manufacturing Engineers.

• Mission: System verification.
• Action: Deep dive. Are the "Red Rabbits" (master failures) working? Is the chemical log up to date?

Tier 3 (Monthly): Performed by Plant Leadership (Plant Mgr, Ops Dir).

• Mission: Cultural enforcement.
• Action: Verify the verifiers. Are Tier 1/2 audits actually happening, or is someone "pencil whipping" the data?

The Binary Question Rule

Ambiguity is the enemy of compliance. Never ask an essay question on a checklist.

Question Design Logic:

• Bad: "Is the workstation organized?" (Subjective opinion).
• Good: "Are there any loose components or unlabelled bins on the active surface?" (Binary Yes/No).
• Bad: "Does the operator know the process?"
• Good: "Can the operator demonstrate the 'Stop Call Wait' protocol for a failed unit?"

Pro-Tip: If an audit question takes more than 10 seconds to answer, delete it. LPAs should take 10 minutes total. If they are burdensome, they will be faked.

Immediate Correction (The "Fix It Now" Rule)

An LPA is not a data-gathering exercise; it is a correction exercise.

Reaction Logic:

• If a non-conformance is found (e.g., loose torque seal) → Then fix it immediately. Do not just tick "Fail" and walk away.
• If the issue cannot be fixed instantly (e.g., broken fixture) → Then stop the line and tag the equipment.
• If the same failure repeats 3 times in a month → Then the Process is broken, not the Operator. Launch a CAPA.

Final Checklist