8.1 Suppliers and Procurement

8.1 Suppliers and Procurement

Quick Answer: External supply planning connects the material plan to capable suppliers through strategic sourcing, make-versus-buy decisions, supplier selection criteria, and supplier relationship management (SRM). CPIM Domain V (Plan and Manage External Supply Sources, ~11%) tests whether you can choose the right sourcing strategy and sustain supplier performance—not just place a purchase order.

When internal capacity, capability, or cost economics cannot cover the material plan, planners rely on external supply sources. That handoff is not a clerical purchase; it is a deliberate design of who supplies what, under which commercial terms, and with what performance expectations. On the exam, questions often start with a capacity gap, a cost trade-off, or a quality failure and ask which sourcing action protects service level at the lowest total cost.

Why External Supply Matters for CPIM

Master schedules and MRP generate planned orders. For purchased items, those planned orders become purchase requisitions and then purchase orders (POs) only after sourcing rules are applied. If sourcing is weak, even a perfect forecast produces late receipts, premium freight, and schedule nervousness. Domain V therefore links planning logic to procurement strategy: supplier lead times feed planning parameters, supplier capacity constrains feasible plans, and supplier performance data closes the loop.

Strategic Sourcing

Strategic sourcing is the structured process of analyzing spend, market structure, and total cost of ownership (TCO) to decide how categories should be bought—and from whom—over a planning horizon longer than a single PO. Tactical buying reacts to a requisition; strategic sourcing designs the supply base before the requisition arrives.

A practical strategic-sourcing sequence looks like this:

1. Profile the category — volume, criticality, specification complexity, and switching cost.
2. Map the supply market — number of capable suppliers, capacity tightness, geographic risk, and price drivers.
3. Define the sourcing strategy — competitive bid, preferred-supplier panel, partnership, or make-versus-buy revisit.
4. Select and contract — award based on weighted criteria, not unit price alone.
5. Govern performance — scorecards, business reviews, and continuous improvement.

Scenario: Strategic Sourcing Decision

A medical-device plant buys machined housings. Annual spend is $4.2M across three suppliers with widely different on-time delivery (OTD). Strategic sourcing consolidates 80% of volume with the top performer under a two-year agreement with indexed raw-material pricing, keeps 20% with a second qualified supplier for continuity, and removes the chronic late supplier. MRP lead time drops from 12 to 8 weeks because the primary supplier commits capacity. The planner updates planning lead time and reduces safety stock once delivery variance stabilizes—exactly the Domain V feedback loop the exam expects.

Make-Versus-Buy Analysis

Make-versus-buy decides whether an item (or process) should be produced internally or purchased externally. CPIM frames the decision around capability, capacity, cost, control, and risk—not slogans about “core competence” alone.

Break-even thinking helps on calculation-style items. If fixed internal setup and overhead are $120,000 per year and variable make cost is $18/unit while buy cost is $26/unit landed, the indifference volume is:

Q = 120,000 / (26 − 18) = 15,000 units/year

Above 15,000 units, making looks cheaper on pure cost; below that, buying wins—unless quality, lead time, or strategic control overturns the arithmetic. Always add freight, inventory carrying cost, tooling amortization, and cost of poor quality to both sides.

Exam Trap: Unit Price Versus TCO

A supplier quoting $0.10 less per unit but requiring a 16-week lead time and 30% higher scrap is often more expensive in TCO. CPIM answers that reward total cost and schedule reliability over the lowest bid.

Supplier Selection Criteria

Selection criteria should be weighted to the item’s risk and impact. Common CPIM-aligned criteria include:

• Quality capability — process capability (Cpk), incoming defect rate, certifications (ISO 9001, IATF, FDA where applicable)
• Delivery performance — OTD, lead-time reliability, ASN accuracy
• Capacity and flexibility — demonstrated capacity, overtime/surge options, alternate sites
• Cost and TCO — unit price, payment terms, tooling, logistics, inventory impact
• Technical support — design collaboration, PPAP/FAI discipline, change notification
• Financial health and ethics — continuity risk, compliance, ESG expectations
• Geographic / geopolitical exposure — transit time, tariffs, single-region concentration

Supplier Relationship Management (SRM)

SRM is the ongoing discipline of segmenting suppliers and managing interactions to improve mutual performance. Not every supplier needs a quarterly executive business review. Segment by risk and value:

SRM closes the planning loop: scorecard trends drive whether planning parameters stay aggressive or become conservative. A supplier slipping from 98% to 88% OTD is a signal to increase safety time or dual-source—not a surprise when the schedule misses.

Single Sourcing Versus Multiple Sourcing

Single sourcing awards essentially all volume for an item to one supplier (distinct from sole sourcing, where only one capable supplier exists in the market). Multiple sourcing splits volume across two or more capable suppliers.

Use single sourcing when collaboration value exceeds disruption exposure and a credible exit plan exists. Use multiple sourcing when continuity or competitive pricing dominates—especially for high-impact A items with scarce capacity. Dual sourcing (a common multiple-source design) often keeps a 70/30 or 80/20 split so the primary supplier stays efficient while the secondary stays qualified.

Planner Checklist Before Firming a Purchased Planned Order

• Confirm approved supplier list and sourcing percentage rules
• Verify planning lead time matches current contractual lead time
• Check open PO and inbound ASN against net requirements
• Review supplier capacity promises for peak periods
• Escalate sole-source or poor-scorecard items to SRM before freezing the MPS

External supply excellence is measured in receipt reliability against the plan, not in purchase-order count. Strategic sourcing chooses the base; make-versus-buy sets boundaries; selection and SRM keep the base capable; single-versus-multiple sourcing balances leverage and resilience.