4.5 Supplier corrective action and effectiveness check

A Supplier Corrective Action Request (SCAR) is not merely an administrative complaint form; it is a formal demand for a systemic engineering change. If a supplier is simply instructed to “fix the bad parts,” they are perfectly positioned to rework the current inventory and potentially ship the exact same defect next month. The fundamental goal of a SCAR is to forcefully drive a permanent improvement in the supplier’s overall process so that the specific defect becomes impossible to reproduce.

SCAR triggers (when to pull the alarm)

Care must be taken not to dilute the impact of a SCAR by issuing one for every minor, one-off discrepancy. They should be reserved for situations where process capability has measurably degraded or systemic risks are exposed.

The Escalation Logic:

• Level 1: Critical (Stop Ship)
  • Trigger: Safety hazards, Regulatory violations (e.g. RoHS/REACH compliance failures), or any severe defect resulting in a “Line Down” event lasting > 4 hours.
  • Response: A 24-hour Containment (D3) plan from the supplier is mandatory.
• Level 2: Major (Systemic)
  • Trigger: A repeat defect (the identical MPN and failure mode occurring within a 90-day window) or an incoming Defect Rate exceeding 1%.
  • Response: A comprehensive 8D Report is required to find the true root cause.
• Level 3: Minor (Trend)
  • Trigger: Persistent documentation errors (like missing CoCs) or a slow, negative trend in the Supplier Scorecard metrics.
  • Response: A standard, simpler Corrective Action Plan (CAP) format is usually acceptable here.

The 8D methodology (mandatory architecture)

Formal, recurring issues require a formal, structured architecture to solve them. Brief “email explanations” for critical failures are not accepted. Suppliers should be required to structure their response using the standard Eight Disciplines (8D) methodology.

• D3: Interim Containment (The Tourniquet)
  • Requirement: The problem must be isolated immediately. The supplier must explicitly define how they screened their suspect stock (e.g. “100% visual inspection under 4x magnification”) and how they identified the verified clean boxes being shipped (e.g. “A Green Dot was placed on the shipping label”).
  • Deadline: Usually expected within 24 Hours.
• D4: Root Cause Analysis (The Pathology)
  • Core Principle: “Operator Error” is almost never a valid Root Cause. If an operator made a mistake, the process failed to prevent or detect that mistake.
  • Tools: Suppliers should provide documented evidence of a 5 Whys or Fishbone (Ishikawa) analysis.
  • Poor D4: “The worker didn’t follow the SOP.”
  • Good D4: “The assembly fixture allowed the part to be loaded backwards because it lacked a mechanical keying pin.”
• D5/D6: Permanent Corrective Action (The Fix)
  • Goal: A systemic or hardware change is expected, not just behavioral retraining.
  • Hierarchy of Intervention: 1. Poka-Yoke (Mistake Proofing): Physical modification to the tooling (Strongest). 2. Process Change: Implementation of Automated Optical Inspection (AOI) or sensors (Strong). 3. Training: An informational update via a team meeting (Weakest - The SCAR must be rejected if this is the entirety of the proposed action plan).
• D7: Prevention (System Update)
  • Requirement: The corrective action must propagate down to the core line documentation. Updates to the supplier’s PFMEA (to demonstrably lower the Occurrence or Detection risk scores) and the corresponding updates to the Control Plan are expected.

Effectiveness verification (VoE)

A SCAR is never closed based simply on a promise; it is closed exclusively on physical evidence.

The “3-Shipment” Rule:

• Guideline: Once a Permanent Corrective Action (PCA) is allegedly implemented, the SCAR enters a “Monitoring” state.
• Action: The subsequent 3 consecutive shipments from the supplier must be entirely defect-free.
  • Pro-Tip: These initial, post-SCAR shipments should be tagged in the ERP system as “Probationary.” IQC should be flagged to perform a 100% inspection specifically focused on the characteristic that previously failed.

Re-Open Logic:

• Guideline: If the exact same defect recurs within 6 months, the previous SCAR was inherently ineffective and the root cause was missed.
  • Action: The issue must be re-opened immediately as a Level 1 Escalation. In this scenario, it is often appropriate to require the supplier’s Quality Director to formally present their revised remediation plan directly to Management.

Final Checkout: Supplier corrective action (SCAR/8D) + effectiveness check

Control Point	Guiding Principle
Response Time	D3 (Containment) action should be delivered within 24 Hours. A late D3 often warrants an immediate New Business Hold.
Root Cause	Focus must remain on the underlying Process/Method failure. “Retrain Operator” must be pushed back on as a valid Root Cause.
Action Plan	A physical or systemic change must be mandated. The plan must robustly address both detection logic and future prevention.
Verification	Three consecutive completely clean lots must be verified. A SCAR must never be fully closed without confirming the incoming IQC data.
Documentation	It must be verified that the supplier’s PFMEA & Control Plan are visibly updated. The fix must be institutionalized into their QMS, not left as tribal knowledge.