Supplier quality improvement

Learning objectives

• Define supplier CTQs and the correct denominator per material family.
• Rank suppliers on like-for-like PPM, capability, delivery and response.
• Design supplier development that prevents defects, not just inspects them.

Problem and CTQ

Incoming fabric, trims, chemicals and service performance drive defects, delay and variability. Ranking suppliers requires like-for-like materials and validated data.

DMAIC path

• Define supplier CTQs and denominator.
• Validate incoming and use-stage data and traceability.
• Stratify supplier/item/lot/time; compare PPM, capability, delivery and response.
• Confirm causes jointly with the supplier.

Improvement choices

• Clear specifications and measurement method.
• Sample approval and process capability plan.
• Corrective action, early-warning data and supplier development.

Control plan

• Supplier PPM, lot acceptance, on-time delivery, SCAR closure and effectiveness, repeat issue, line disruption and total cost.

Garment-factory example

Two twill suppliers run at PPM 5,200 and PPM 8,900 on shade delta; deeper look shows the second supplies a stripe fabric with stricter matching. Comparing only plain fabric lots, the two suppliers are within 300 PPM of each other, and the joint action shifts to matching tolerance.

Common mistakes

• Ranking unlike materials on raw counts.
• Relying on incoming inspection instead of supplier process control.