FREE SUPPLY CHAIN PLANNING LEARNING PATH

WikiFree original practice workbook

The logistics atlas

CASE STATUS: fictional/synthetic teaching material. Do not present the example as real research, employment experience or measured business performance.

OUTCOME
Build a simple replenishment and supplier-comparison plan using demand, lead time and service assumptions.

BEFORE YOU START
Comfort with averages and inventory arithmetic; this route introduces planning concepts through a small case.

CASE
Birch Repair Shop uses a common spare part. Average demand is eight units per working day. Supplier A takes four days; Supplier B takes two. A simple case rule adds two days of demand as a buffer. This is a deterministic training model, not a statistically optimized inventory policy.

INPUTS
Supplier,"Lead time, days",Unit cost,Freight per order
A,4,6,20
B,2,7,10


ENTRY CHECK

Question: Is inventory on hand the whole inventory position?

Self-check: No. Add on-order stock and subtract backorders under the stated convention.

Question: Can the cheapest unit price have a higher order cost?

Self-check: Yes. Freight, batch size and other consequences matter.

Question: Does a two-day buffer prove a service level?

Self-check: No. It is a case assumption, not a quantified probability of avoiding stockouts.

STAGE 1: Draw the supply network

Prerequisite: Comfort with averages and inventory arithmetic; this route introduces planning concepts through a small case.

Instruction: A supply plan connects the demand point, stock location and supplier. Identify the information that moves in the opposite direction to physical goods: requests, orders, confirmations and receipts. A diagram should expose a decision owner and a dependency, not imply that a supplier’s quoted lead time is guaranteed. The numbered MIT lectures provide broad context; the Birch calculations are original practice.

Practice task: Map the shop, store and two suppliers. Mark who observes demand, raises an order and checks the receipt.

Deliverable: A supply network and responsibility map

Acceptance check: Physical and information flows are distinguishable and each replenishment decision has an owner.

If stuck: If the map ends at dispatch, add receipt verification and the treatment of short deliveries.

Record your work, decisions and evidence:




Record your result against the acceptance check:



STAGE 2: Translate demand into coverage

Prerequisite: Bring your previous output: A supply network and responsibility map

Instruction: Days of cover divides usable stock by a demand-rate assumption. It is a planning view, not a promise. Inventory position includes on-order units and subtracts backorders when those definitions are consistent. Do not count damaged stock as available or ignore demand already owed. State whether the rate uses working days or calendar days.

Practice task: Use 25 usable units on hand, 15 on order and four backordered. Calculate inventory position and on-hand days of cover at eight units per working day.

Deliverable: An inventory-position calculation

Acceptance check: Position is 36 units; on-hand cover is 3.125 working days.

If stuck: If cover uses 40 units, separate physical availability from goods that have not arrived.

Record your work, decisions and evidence:




Record your result against the acceptance check:



STAGE 3: Set a transparent reorder rule

Prerequisite: Bring your previous output: An inventory-position calculation

Instruction: A simple reorder point can combine demand during lead time with an explicit buffer. Here the buffer is two days of average demand. This does not model demand variability, supply variability or a target service probability. Write the assumption beside the formula so a future user does not mistake it for an optimized safety-stock calculation.

Practice task: Calculate reorder points for both suppliers and decide whether a position of 36 triggers ordering under each rule.

Deliverable: Two reorder rules and a trigger decision

Acceptance check: A has a 48-unit threshold and triggers; B has a 32-unit threshold and does not.

If stuck: If the same threshold is used for both, revisit the lead-time assumption.

Record your work, decisions and evidence:




Record your result against the acceptance check:



STAGE 4: Compare a feasible order

Prerequisite: Bring your previous output: Two reorder rules and a trigger decision

Instruction: Compare options using the same order quantity and relevant boundary. For a 40-unit order, unit cost plus freight is a simple landed-order estimate. It excludes storage, shortages and quality costs, so those remain separate considerations. A faster supplier can be worth considering when lead-time uncertainty threatens service, even if its direct order cost is higher.

Practice task: Compare a 40-unit order from A and B. Add one service risk and one quality question that the arithmetic alone cannot resolve.

Deliverable: A supplier comparison and evidence gaps

Acceptance check: Direct order costs are 260 and 290; the 30-unit difference is not treated as the whole decision.

If stuck: If an option wins only on price, state the operational consequence of its lead time.

Record your work, decisions and evidence:




Record your result against the acceptance check:



STAGE 5: Prepare an exception plan

Prerequisite: Bring your previous output: A supplier comparison and evidence gaps

Instruction: A replenishment policy needs an exception route for late deliveries, changed demand and inaccurate stock records. Set an observable trigger and name the decision owner. Keep emergency orders visible because repeated expedites may indicate a broken baseline process. Review the policy after new evidence; do not silently update the demand rate to justify an earlier decision.

Practice task: Simulate Supplier A slipping from four to six days. Recalculate its threshold under the case rule and draft a response with a record-review action.

Deliverable: A disruption response and policy review

Acceptance check: The revised threshold is 64 units and the reason for changing it is recorded.

If stuck: If the response is only order more, explain delivery timing, existing commitments and the stock-record check.

Record your work, decisions and evidence:




Record your result against the acceptance check:



WORKED CASE
Inventory position is 25+15−4=36. A’s reorder point is 8×4+8×2=48; B’s is 8×2+16=32. Forty units cost 40×6+20=260 from A or 40×7+10=290 from B. These are case calculations; a real policy needs measured variability and operational constraints.

FINAL PROJECT
Build the Birch planning pack: network, inventory definitions, reorder rules, supplier comparison and a late-delivery exception plan.

REQUIRED CRITICAL CHECK
Do not label the case buffer as a guaranteed service level or treat on-order stock as physically available.

SCORING
Score each of the five stage acceptance checks from 0–16 (0 missing/incorrect; 8 partially supported; 16 complete and evidenced). Score the final integrated project from 0–20 (0 missing; 10 incomplete handover; 20 complete, reproducible and consistent with the case). Target: at least 80/100 AND the critical check must pass. A total score never overrides a failed critical check.

SCOPE LIMIT
This is an introductory deterministic model. Demand forecasting, statistical safety stock, contracts and global logistics require further study.

SOURCES AND ACCESS
Assigned public videos can be watched free. Complete the original case in a text editor, on paper or in a spreadsheet you already have. No paid course, exam or provider certificate is included.

Free MIT Course: Supply Chain Strategy and Logistics
WikiFree: https://wikifree.com/courses/mit-supply-chain-strategy-and-logistics/
Official source: https://www.youtube.com/playlist?list=PLF9071540F59BA1F0
Why selected: The first four published MIT lectures provide supply-chain context. The worked replenishment model is original and is not presented as a named provider lesson.

Stage 1 selected lessons:

1. Lec 1 | Special Topics in Supply Chain Management (11:18)
https://www.youtube.com/watch?v=IqmrNUoiy7g&list=PLF9071540F59BA1F0&index=1

2. Lec 2 | Special Topics in Supply Chain Management (42:06)
https://www.youtube.com/watch?v=djrhQK-dBx0&list=PLF9071540F59BA1F0&index=2

Stage 4 selected lessons:

3. Lec 3 | Special Topics in Supply Chain Management (52:28)
https://www.youtube.com/watch?v=uON1av7YiHw&list=PLF9071540F59BA1F0&index=3

4. Lec 4 | Special Topics in Supply Chain Management (44:55)
https://www.youtube.com/watch?v=KIkTU03nGxc&list=PLF9071540F59BA1F0&index=4

REUSE
Original WikiFree teaching text and synthetic fixtures are supplied for personal learning and adaptation with attribution. Provider lessons remain on their original sites and retain their own terms. No provider certificate is included.