16.1 Planning Hierarchy Integration

Why Integration Matters on the CPIM Exam

The live ECM 9.0 CPIM exam is a single computer-based test covering nine domains. ASCM no longer uses the retired Part 1 / Part 2 split. Many high-weight items test whether you can connect planning levels—not whether you can define one acronym in isolation. When a demand signal changes, you must trace the ripple from Sales and Operations Planning (S&OP) down through Master Production Scheduling (MPS), Material Requirements Planning (MRP), Capacity Requirements Planning (CRP), Production Activity Control (PAC), and into distribution.

Think of the hierarchy as a translation engine: strategy and volume plans become item schedules, schedules become component and capacity plans, and capacity plans become shop-floor and logistics actions. If any link is broken, inventory, service, and cost all degrade together.

The Planning Cascade at a Glance

Exam cue: S&OP balances aggregate demand and supply for product families. MPS disaggregates into specific items and periods. MRP explodes bills of material (BOMs). CRP validates resources. PAC executes. Distribution positions finished goods for customers.

Connecting S&OP to MPS

S&OP produces a volume agreement—often monthly buckets by family—covering demand, production, inventory, and sometimes backlog or capacity. The MPS then converts that volume into a time-phased mix of end items (or other MPS items such as options or modules in some environments).

Key integration rules:

• The sum of MPS item quantities in a period (or rolling window) should reconcile to the S&OP family plan, within agreed tolerances.
• If marketing raises family demand in S&OP, the MPS must either raise end-item schedules, consume safety stock, or force a new S&OP decision if capacity or materials cannot support the increase.
• Available-to-promise (ATP) and rough-cut capacity checks often sit between S&OP and detailed MRP so sales can quote without overselling the master schedule.

When examiners ask “which plan drives the other?” remember the direction of authority: S&OP sets the volume envelope; MPS lives inside it—unless a formal exception escalates back to S&OP.

MPS to MRP: Time-Phased Need

Once the MPS states when finished items are needed, MRP uses:

• BOM structure (parent → components)
• Inventory on hand and on order
• Lead times and lot-sizing rules
• Gross requirements derived from parent plans

MRP answers gross-to-net logic (covered in depth in Section 16.2): subtract on-hand and scheduled receipts from gross requirements, then offset by lead time to create planned order releases. A change at MPS almost always changes component due dates and purchase/manufacturing releases.

MRP to CRP: Feasibility Check

MRP assumes infinite capacity unless you explicitly constrain it. CRP takes planned and released orders, multiplies by routing times (setup + run), and loads work centers by period. Integration failures show up as:

• Overloaded critical work centers while other centers sit idle
• Plans that look material-feasible but are capacity-infeasible
• Endless expediting because PAC inherits an impossible MRP output

Healthy integration means capacity problems are resolved before release—by overtime, alternate routings, lot splitting, outsourcing, or revising the MPS/S&OP—not discovered only when jobs queue on the floor.

CRP to PAC: From Plan to Dispatch

Production Activity Control manages release, priority, tracking, and completion. PAC uses shop orders, dispatch lists, input/output control, and often priority rules (critical ratio, earliest due date, slack). If CRP said a work center is at 110% of available hours, PAC will still try to run the queue—but lead times stretch, overdue work rises, and distribution promises break.

Integration exam items often ask what PAC should do when priorities conflict: protect the schedule that supports customer promise dates, escalate capacity constraints, and avoid local optimization that starves downstream operations.

Distribution: Closing the Loop to the Customer

Distribution planning (including Distribution Requirements Planning (DRP) in many multi-echelon networks) takes independent demand at warehouses/DCs and creates replenishment orders on plants or central stock. The same ripple logic applies outbound:

• A demand spike at a regional DC raises DRP gross requirements.
• That can increase plant MPS demand (or warehouse replenishment orders treated as dependent demand on the plant).
• Plant MRP/CRP/PAC then feel the same cascade.

Conversely, a plant delay in PAC can force distribution to reallocate, expedite freight, or substitute inventory across DCs—raising logistics cost to protect service.

One End-to-End Scenario: The Sudden Promo Lift

Setting. Northwind Appliances runs monthly S&OP for the “Countertop Blender” family. The agreed March production volume is 10,000 units. The MPS splits that into SKUs: Model A 6,000 and Model B 4,000 across weekly buckets. Component X (motor assembly) has a two-week manufacturing lead time. Work Center 20 (final assembly) has 400 available hours/week. Distribution ships from a central DC to two regional DCs.

Trigger. On Monday of week 1, Sales confirms a retailer promo that adds 2,000 units of Model A demand in week 4 (beyond the forecast already in S&OP).

Ripple 1 — S&OP / demand consensus. Demand planning flags the lift. If the promo was not in the S&OP demand plan, the team must decide: absorb with inventory, raise production, or decline/shift the promo. Assume leadership approves a +2,000 family volume increase for March and updates the S&OP production plan to 12,000.

Ripple 2 — MPS. Master scheduling adds Model A into week 4 (or earlier weeks if lead-time offsets require it). ATP for Model A drops until the extra supply is scheduled. Sales holds new quotes until ATP is refreshed.

Ripple 3 — MRP. Exploding Model A’s BOM creates additional gross requirements for Component X and packaging. Netting shows a shortage; MRP creates a planned order release two weeks before the new assembly need—so purchasing/manufacturing must act in week 2 for a week-4 assembly increase.

Ripple 4 — CRP. Extra Model A assemblies add hours to Work Center 20 in week 4. Load rises above 100%. Planners authorize Saturday overtime and move a noncritical job to week 5.

Ripple 5 — PAC. Dispatch lists in weeks 2–4 prioritize Component X and Model A kits. Input/output control watches Work Center 20 so overtime actually lands on the promo jobs, not on easy fills.

Ripple 6 — Distribution. DRP at the East DC raises replenishment from the central DC for week 4 retail ship dates. Transportation books extra outbound capacity. West DC stays flat—no blind push of inventory that would steal stock from the promo region.

Exam takeaway from the scenario: a demand change is never “just a forecast edit.” It is a chain of reconciled decisions across volume, mix, materials, capacity, execution, and network placement. CPIM expects you to name the next affected plan and the correct corrective action at each link.

Failure Modes Examiners Love

Closing the Integration Loop

After PAC completes and distribution ships, performance feeds back into the next S&OP: forecast accuracy, schedule attainment, inventory turns, and fill rate. Integration is bidirectional. The best CPIM answers show that feedback—not only the top-down cascade.