Where do inputs come from?
Supplier, region, tier?
Cost, quality, capacity and concentration all shape upstream risk.
Side 43
Supply Chain
& Logistics
A study of how materials, information and commitments move from source to customer. Supply chains coordinate sourcing, transformation, inventory, transport, warehousing and service across networks with finite capacity and uncertainty.
source→transform→store→move→fulfill
06flow stages
05inventory questions
06resilience lenses
43Side
A supply chain is a network of flows and commitments.
Physical movement, information, cash and ownership can follow different paths through the same system.
Where is value added?
Factory, assembler, processor?
Transformation introduces capacity, yield and scheduling constraints.
Where is inventory held?
Plant, DC, store, in transit?
Inventory location trades responsiveness against duplication and working capital.
Which lanes connect the network?
Mode, route, frequency?
Transport design affects cost, speed, reliability and emissions.
How does demand become delivery?
Order promise to receipt.
Service depends on the whole chain rather than the final warehouse alone.
Planning translates uncertain demand into commitments.
Forecasts guide capacity, purchasing and inventory, but errors propagate when plans are treated as facts.
Estimate future demand.
Accuracy depends on horizon, product maturity, seasonality and aggregation level.
Time between decision and availability.
Long lead times force earlier commitments and increase exposure to forecast error.
Maximum feasible throughput.
Nominal capacity can differ from sustainable capacity after changeovers, maintenance and variability.
Align demand and supply plans.
Sales and operations planning reconciles commercial expectations with operational constraints.
Small demand changes amplify upstream.
Batching, delays and overreaction can create larger order swings than underlying customer demand.
Delay irreversible differentiation.
Keeping products generic longer can reduce forecast error at the final variant level.
Inventory is both buffer and burden.
It protects against uncertainty while consuming capital, space and attention.
Cycle stock
Inventory created by order batches.
Larger replenishment quantities reduce ordering frequency but raise average stock.
Safety stock
Buffer against uncertainty.
Demand and lead-time variability determine how much protection is needed for a target service level.
Pipeline
Inventory already moving.
Long transit times can tie up substantial working capital even before goods reach a warehouse.
Reorder point
When should replenishment trigger?
The reorder point must cover expected demand during replenishment plus appropriate safety stock.
Obsolescence
Buffers can decay in value.
Perishability, model changes and demand shifts can turn excess inventory into loss.
Inventory logicbuffer against uncertainty ↔ cost of carrying the buffer
Logistics converts geography into cost and time.
Transport mode, network design and warehouse operations determine how physical flow performs.
| Mode | Strength | Constraint | Typical fit |
|---|---|---|---|
| Ocean | Low unit cost at scale | Slow, port dependent | Large international flows |
| Rail | Efficient bulk inland transport | Fixed network | Heavy long-distance freight |
| Truck | Flexible door-to-door reach | Higher unit cost, congestion | Regional and final-mile freight |
| Air | Very fast | High cost, capacity limits | Urgent/high-value goods |
| Parcel / courier | Dense small-shipment network | Unit-cost premium | E-commerce and documents |
Place items by movement profile.
Fast-moving products near efficient pick paths can reduce labor travel.
Transfer with little storage.
Useful when synchronized inbound and outbound flows reduce the need to hold inventory.
Combine shipments.
Higher vehicle utilization can lower cost while increasing wait for load accumulation.
Service is a supply-chain output.
Availability and delivery reliability are shaped by inventory, capacity, transport and information quality together.
How much demand is immediately served?
Measures units fulfilled from available stock rather than merely whether an order had any stockout.
On time and in full.
Captures whether the complete promised quantity arrives within the agreed window.
Right product, quantity, timing and documentation.
A composite service view exposes failures beyond simple delivery speed.
Time from order to receipt.
Reducing average cycle time without reducing variability may not improve customer planning much.
Do commitments match capability?
Accurate available-to-promise logic can be more valuable than aggressive but unreliable dates.
Service consumes different resources by customer.
Small orders, remote delivery and special handling can radically change economics.
Efficiency removes slack; resilience decides which slack was valuable.
Supply-chain resilience is the capacity to absorb disruption, adapt and restore critical flow.
Visibility
Map suppliers, inventory, transit and dependencies far enough upstream to see emerging disruption.
Diversification
Alternative suppliers, routes or regions reduce dependence when substitutes are genuinely independent.
Buffer
Strategic inventory, spare capacity or time can absorb variability at explicit carrying cost.
Flexibility
Interchangeable materials, plants and transport modes increase options under disruption.
Priority
Scarce supply should be allocated by criticality rather than first request alone.
Recovery
Preplanned escalation, alternate sourcing and logistics pathways shorten disruption duration.
Supply Chain ManagementChopra & Meindl · design and planning
Designing and Managing the Supply ChainSimchi-Levi et al. · network and logistics
Factory PhysicsHopp & Spearman · variability and flow
The Resilient EnterpriseYossi Sheffi · disruption and resilience