4.1 Rolling forecast: horizon rules & capacity reservation

Manufacturing is a momentum machine; it cannot turn on a dime. The Rolling Forecast is the steering mechanism. It bridges the gap between the customer’s immediate sales reality and the factory’s physical lead times (often 12–20 weeks). A forecast is not a “guess”; it is a financial instrument that authorizes the factory to hire labor and purchase material. Without a disciplined forecast, the supply chain oscillates between shortage (revenue loss) and excess (cash flow death).

The horizon structure (zones of liability)

The forecast is segmented into three specific time horizons. Each zone carries a different level of commitment and flexibility.

Zone 1: the frozen zone (execution)

• Timeframe: Weeks 1 – 4 (Current Month).
• Status: Binding.
• Action: Production is scheduled; lines are staffed.
• Flexibility: 0%. No push-outs allowed. Changes require a “Line Down” fee.
• Requirement: Must be covered 100% by a hard Purchase Order (PO).

Zone 2: the slush zone (material authorization)

• Timeframe: Weeks 5 – 12 (Quarter + 1).
• Status: Semi-Binding.
• Action: Long Lead Time (LLT) materials are purchased. Driver ICs, PCBs, and connectors are ordered.
• Flexibility: ± 20%. Volume can shift, but the liability for unique materials is locked.
• Requirement: Covered by NCNR (Non-Cancellable Non-Returnable) agreement.

Zone 3: the liquid zone (planning)

• Timeframe: Weeks 13 – 52.
• Status: Non-Binding.
• Action: Capacity planning and strategic sourcing agreements.
• Flexibility: 100%. This is the signal used to reserve production capacity.
• Requirement: credible market data.

Commitment transfer:

• Forecast entries moving from Zone 2 into Zone 1 require the immediate issuance of a firm Purchase Order (PO) to cover execution.
• Demand drops occurring while the product is in Zone 2 leave the Customer responsible for the raw material liability already incurred.

Signal vs. commit

A forecast submission is a “Signal.” It asks the question: “Can you build this?”

The factory’s response is the “Commit.” It answers: “Yes, we have the components and workforce.”

The two must not be conflated. A Customer Forecast of 10k units is meaningless if the Factory Commit is 5k due to a component shortage.

The golden rule of reservation

Capacity is reserved based on the Forecast, not the Purchase Order (PO).

• Scenario: Customer forecasts 5k/month for Q3.
• Action: Factory reserves 5k/month of capacity.
• Risk: If a Customer sends a PO for 10k/month in Q3 without a prior forecast signal, the Factory will reject the excess 5k. Capacity is allocated on a First-Come-First-Served basis defined by the forecast signal.

Engineering Practice

“Phantom Demand” destroys trust. If a customer consistently forecasts 10k but only orders 5k to “secure safety stock,” their capacity priority must be downgraded. Capacity reservation must be based on their actual “Consume Rate” (historical data), not their optimism.

Forecast policy (the rules of engagement)

These rules must be embedded in the Master Supply Agreement (MSA).

Rule	Definition	Consequence of Breach
Cadence	Forecast submitted every Monday by 12:00 p.m..	Late submission = Current week production plan slides 1 week.
Horizon	Minimum 12-month visibility required.	< 12 months = Lead times for strategic parts extend to market standard.
Variance	Zone 1 variance limit: 0%. Zone 2 variance limit: ±20%.	Excess demand is “Best Effort” only. Shortfall triggers material liability invoice.
End of Life	EOL ramp-down must be visible 6 months prior.	Sudden stop = Customer billed for 100% of stranded inventory.

The forecast response template

The factory must formally respond to the forecast within 48 hours. Silence implies acceptance, which is dangerous. This format should be used to flag constraints.

Header: Customer | Forecast Date | Reviewer

Section 1: The Green Zone (Accepted)

• Statement: “Weeks 1–8 demand is fully supported. Material and Capacity secured.”

Section 2: The Constraint Log (Red Flags)

• Constraint 1: Week 10 request (5,000 units).
  • Capability: 3,500 units.
  • Root Cause: Shortage of PMIC (Part #XYZ).
  • Recovery: 1,500 balance moves to Week 12.
• Constraint 2: Week 18 request (12,000 units).
  • Capability: 8,000 units.
  • Root Cause: Test Station Capacity (CapEx required).
  • Action: Customer must approve CapEx expenditure by [Date] to unlock volume.

Section 3: Liability Alert

• Warning: Based on this forecast, we are placing orders for [List Critical Components] totaling $[Value].
• Action: Please acknowledge liability by return email.

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Recap: Rolling Forecast Horizon Rules & Capacity Reservation

Zone	Timeframe (Weeks)	Flexibility / Variance Limit	Requirement / Coverage	Action / Consequence
Frozen (Execution)	1 – 4	0%	100% firm Purchase Order (PO)	Production scheduled. No push-outs. Changes incur “Line Down” fee.
Slush (Material)	5 – 12	±20%	NCNR (Non-Cancellable Non-Returnable) agreement	LLT materials purchased. Shortfall triggers material liability invoice.
Liquid (Planning)	13 – 52	100%	Credible market data	Capacity planning & strategic sourcing. Signal for capacity reservation.
Policy Rule	Requirement	Consequence of Breach
Cadence	Submitted every Monday by 12:00 p.m.	Late submission = Production plan slides 1 week.
Horizon	Minimum 12-month visibility	<12 months = Lead times extend to market standard.
EOL Visibility	Ramp-down visible 6 months prior	Sudden stop = Customer billed for 100% stranded inventory.
Core Principle	Rule	Document / Basis
Capacity Reservation	Based on forecast signal, not Purchase Order (PO).	MSA, “Golden Rule”
Commitment Transfer	Forecast moving from Zone 2 to Zone 1 requires immediate PO.	Transfer procedure
Forecast Response	Factory must respond formally within 48 hours.	Response template (Silence implies acceptance).