Kanban replenishment

In the fixed-container example, 80 units/working day over 1.5 days replenishment and 0.5 day scan delay, plus 40 units of buffer, gives a 200-unit target loop. With 30-unit containers and upward rounding, select 7 containers for 210 units of nominal loop coverage. That coverage includes material circulating through the loop. It does not specify how much is physically on the shelf at one moment.

LEI distinguishes production kanban authorizing work from withdrawal kanban authorizing movement. A card, container or electronic signal can carry part ID, source, destination and pack quantity. Lean Enterprise Institute, kanban.

Toyota describes an upstream stock point that replenishes what the next process withdraws. Toyota Motor Corporation, Toyota Production System.

Define the physical loop and its signal

For each item or permitted family, identify source, destination, standard container quantity, trigger event and replenishment completion point. A signal issued when the first piece is removed has a different remaining-stock boundary from a signal issued when a bin becomes empty. State which one is used before sizing the loop.

Production and withdrawal authorizations need not be interchangeable. In LEI’s two-signal example, withdrawal from an upstream supermarket removes a production kanban, which returns to the supplying process to authorize replacement. The withdrawal kanban accompanies the moved container. Its description emphasizes that production and movement do not occur without their corresponding authorization. Lean Enterprise Institute, production and withdrawal kanban.

A practical loop definition should also establish how a signal returns, who can replace a lost card, how an electronic request is acknowledged, and how completed replenishment closes the request. These are implementation decisions: a board showing “empty” is insufficient if nobody is responsible for producing or moving the replacement.

Measure the complete replenishment delay

Measure from the actual trigger until good material is available at the consuming location. Include signal collection/transmission, waiting for a production slot or delivery, setup, processing, inspection/release, transport and put-away as applicable. Keep working-day calendars and nonworking periods explicit. A supplier’s manufacturing time alone may omit most of this delay.

Oracle JD Edwards 9.2 illustrates why signal delay matters. Its fixed-container/high-demand equation includes delivery lead time plus scan-delta days, then adds safety stock. It calculates cards by dividing the resulting quantity by container size. This is a specific software calculation, not the only valid kanban design. Oracle, Kanban Equation 1.

Frequent collection can reduce information delay, but the route must actually run at that frequency. LEI’s paced-withdrawal description connects a fixed material-handler circuit with the release of production instructions and withdrawal of completed items; its illustrated 20-minute route is an example, not a universal frequency. Lean Enterprise Institute, paced withdrawal.

Original sizing example: distinguish coverage from containers

Assume an invented fixed-container calculation following the structure of Oracle’s Equation 1:

The target loop quantity is:

80 × (1.5 + 0.5) + 40 = 200 units.

The unrounded container count is 200/30 = 6.667. Under the explicitly assumed policy of rounding upward to full containers, select seven containers, representing 210 units of authorization. Six represent only 180 units, 20 below the target. Rounding creates a ten-unit increment above the calculated target; that increment is distinct from the specified 40-unit safety allowance.

If scan delay falls to zero while all other inputs remain fixed, the calculated quantity becomes 80 × 1.5 + 40 = 160 units. Upward rounding gives six containers, representing 180 units. This comparison demonstrates the effect of the stated delay assumption, not proof that one card can safely be removed from an operating loop.

The example is a sizing balance, not a stochastic service-level calculation. It does not imply that 40 units achieves a particular stockout probability. Nor are all 210 authorized units necessarily full containers physically on the consumer’s shelf: some authorizations can correspond to work being replenished or transported. Establish whether the active container at consumption is included in the loop definition; do not add or omit an extra container without reconciling that boundary. Validate actual trigger timing, demand variation, replenishment performance and container states before changing the live count.

Oracle also documents an alternative in which the number of cards is fixed and container quantity is calculated instead. Do not silently exchange that decision with a fixed-container calculation. Oracle JD Edwards 9.2, Equation 3.

Kanban can coexist with planning

Kanban execution does not remove the need to plan supplier capacity, purchased material or future demand. SAP ERP 6.0 EHP6 documents two arrangements: replenishment solely from kanban signals, or planning proposals that preview future consumption while kanban still triggers replenishment. Those are named implementation options, not a rule that every MRP run must create executable supply in parallel with kanban. SAP, KANBAN Replenishment: With or Without MRP.

Avoid duplicate authorization: determine whether a forecast, purchase release, production order and kanban signal are planning information or separate executable demands. Reconcile open replenishments before issuing another request for an apparent shortage.

Product terminology also differs. Microsoft’s Dynamics 365 tutorial creates an event rule of type Withdrawal, using minimum-stock replenishment and batch event processing. Its 200-piece minimum and USMF location are demonstration data, not recommended thresholds for another plant. A software feature named kanban can therefore use a trigger that differs from a physical card-return loop. Microsoft, minimum-stock event tutorial, updated August 26, 2024.

Operate and revise the loop deliberately

Track shortages, late replenishments, damaged containers, missing or duplicate signals and unusable stock separately. Quarantined or rejected material should not be treated as usable coverage merely because it occupies the assigned location. Investigate the cause of a shortage before increasing cards indefinitely: an incorrect pack quantity, missed pickup or persistent capacity deficit requires a different correction from random demand variation.

Electronic kanban retains the information-control requirement. Toyota Systems describes specifying which parts, where, when and how many, and digitizing the communication between plants and suppliers. That supports a traceable signal, not a claim that scanning itself eliminates overproduction or guarantees delivery. Toyota Systems, kanban system overview, labelled FY2024.

For handoff, retain item/revision, source/destination, trigger, container quantity, authorized count, lead-time boundary, safety assumption, calendars and exception ownership. Record why counts change and remove obsolete signals deliberately. The selected count should remain distinguishable from on-hand stock, outstanding replenishment and a purchasing commitment.

Source versions

Reviewed 2026-11-01. Oracle links identify JD Edwards 9.2; SAP identifies ERP 6.0 EHP6. Microsoft’s tutorial displays August 26, 2024 as its update date. Toyota Systems labels its feature FY2024, which is not an exact publication date. No separate publication date is assigned to the cited LEI or Toyota Motor Corporation pages. Numerical examples and handoff recommendations are original and bounded to their stated assumptions.