Start with something familiar
Imagine planning a meal for a group of friends. You need to know who is coming, what each dish uses, which food is already usable, and when the oven is free. A full pantry does not help if the missing ingredient arrives after dinner. Nor does a long recipe prove that you can cook it before guests arrive. Manufacturing planning applies that same care to parts, unfinished work, available time, and the promises made to customers.
Words to know: Firming, Time fence.
Define the planning boundary
A proposal is permission to investigate; a released order is permission to execute under the organization’s rules. Northstar uses a release gate to avoid sending attractive but impossible quantities to the shop. The gate checks the item version, material, usable capacity, due date, and accountable owner.
The shared baseline needs twenty nine additional good bottles. Supplier availability is twenty four good-unit equivalents, manufacturing can support thirty two, and shipping can handle thirty. These figures are expressed on a comparable good-unit basis for this screen. The smallest limit is twenty four, leaving a five-unit gap before recovery.
Calculate with explicit rules
Do not confuse that screen with the later start calculation. Once enough material for the target is confirmed, twenty nine expected good units still require thirty starts at ninety seven percent yield. A supplier limit stated in raw bodies would need conversion before comparison with good units. The exercise deliberately labels the units to avoid that trap.
A release checklist should have evidence, not only check marks. Record the receipt confirmation, approved BOM version, resource slot, and shipping cutoff. An owner should know which evidence becomes stale when demand changes. A changed due date can invalidate the slot even if the quantities remain unchanged.
Check before committing
Use a time fence to describe how changes are handled, not to pretend that changes cannot happen. Northstar’s next two days are frozen: any quantity or date change requires planner and shop approval. Outside the fence, the planner may revise proposals, but must still rerun dependent material and capacity checks.
When the gate fails, record a specific exception. State the missing quantity, affected demand, latest useful decision time, and candidate remedy. The system should preserve the original need even if it releases only the feasible part. Otherwise a partial release can make an unresolved customer obligation disappear from view.
- Read case inputs
- Calculate the baseline
- Change one assumption
- Check and decide
Northstar worked case
All data below are fictional and complete for this calculation.
| Input group | Exact case data |
|---|---|
| 1 | Net good need29; supplier available24 good-equivalent units; manufacturing32;shipping30. |
| 2 | Recovery option: supplier adds5 timely good-equivalent units for$40. Manufacturing and shipping limits unchanged. After recovery use30 starts at97% yield and390min load within480min. |
- 1. Before recovery feasible=min(29,24,32,30)=24;gap5.
- 2. After confirmed addition,supplier29 and feasible29;screen gap0.
- 3. Expected output at30 starts29.1 remains uncertain, even when deterministic gates pass.
Base feasible[24,30,18,28];gaps[5,5,2,3].
Assumptions
- Only the stated supply and demand exist; no hidden safety stock or open orders.
- Timing, yield, lot size, and setup follow the explicit case; do not import another lesson’s assumptions.
Where this can fail: This deliberately small model checks planning logic. It cannot establish supplier reliability, customer priority, or a statistical service guarantee.
Build, test and explain a plan
Northstar asks you to build a reusable planning model, not just report one answer. Use only the inputs below and the worked example. Net good need29; supplier available24 good-equivalent units; manufacturing32;shipping30. Recovery option: supplier adds5 timely good-equivalent units for$40. Manufacturing and shipping limits unchanged. After recovery use30 starts at97% yield and390min load within480min. Keep full precision in intermediate calculations and round only where the case requires whole units. Use separate tabs or clearly labeled paper grids for the baseline and each scenario. The eight hours are a self-paced practice estimate, not an experimentally validated duration.
Use paper or a spreadsheet. The estimates below include the study and worked example already on this page.
| Estimated hours | Activity |
|---|---|
| 0.5 | Study the terms and mark each input with its unit, date, and status. Write a half-page statement of the boundary of the model and list facts that are deliberately excluded. |
| 0.5 | Recalculate every worked-example step by hand. Compare the hand calculation with your model and explain any difference before moving on. |
| 3 | Build four gates with needs[29,35,20,31],supplier[24,40,18,36],manufacturing[32,30,25,34],shipping[30,33,24,28]. Build formulas, a visible input table, and a reconciliation row. Add notes so another learner can reproduce the model without asking you for missing data. |
| 2 | Add5 supplier units in each case; separately add5 shipping units. Keep the two interventions independent and identify which resolves the limiting resource. Save each scenario separately. Compare quantities, dates, and any unresolved shortages. Trace the change from its input through every affected calculation. |
| 1 | Write a one-page decision memo naming the baseline result, the preferred action under each scenario, the remaining uncertainty, and the evidence required before execution. Do not invent costs or customer priorities. |
| 1 | Create a five-minute teach-back with one diagram and one checked number. Then use a second independent calculation to audit the model and revise unclear assumptions. |
Your deliverables
- An auditable input and calculation table with baseline and scenario tabs.
- A comparison table with numerical checks, dates, and unresolved gaps.
- A decision memo and a short teach-back using the supplied facts.
Check your practice work
- Base feasible[24,30,18,28];gaps[5,5,2,3].
- Supplier-only addition yields[29,30,20,28];gaps[0,5,0,3].
- Shipping-only addition yields[24,30,18,31];gaps[5,5,2,0].
Keep these three ideas
- Turn proposals into executable orders with a small release gate.
- A numerical answer must retain its unit, timing, and assumptions.
- Use the scenario checks to test the model before using it to support a decision.
Common mistakes
- Combining values that refer to different dates or different physical units.
- Treating a modeled proposal or expected output as confirmed usable supply.
Optional video study
Turn proposals into executable orders with a small release gate.
- A proposal is permission to investigate; a released order is permission to execute under the organization’s rules
- Before recovery feasible=min(29,24,32,30)=24;gap5.
- Base feasible[24,30,18,28];gaps[5,5,2,3].
First half: definitions and baseline.
Open the module media & quizPut this idea to use
Carry your assumptions into a practical tool, then compare your result with a short guide.
Open a related planning toolRead the related planning guidePractice with the planning gameThis saves a completion marker in this browser only. It does not verify time spent.