Kanban Signals Fail When the Response Is Undefined

A Kanban signal is useful only when someone knows what it authorizes and how to respond. Clear quantities, locations, responsibilities, and replenishment timing turn a visible card or empty bin into a dependable process.

Follow a signal from trigger to delivery

Observe what happens when the signal appears. Who notices it? Where does it go? Does it authorize a move, production, or an external replenishment action? How is the completed response recognized?

Watch for gaps between functions. Production may assume the warehouse collects cards while the warehouse expects a digital request. A board full of signals can look organized while the underlying material response remains informal.

Define the operating rule

For each pilot loop, document the part, quantity, unit, source, destination, trigger, responsible role, and expected response. Make clear how partial containers, damaged material, unavailable stock, and lost signals are handled.

In a hypothetical two-bin arrangement, using the final piece in one bin may trigger replenishment while the second supports continued work. That arrangement only works if the remaining supply covers the actual response conditions. Copying another area's bin size without checking consumption and lead time creates a false sense of protection.

Treat exceptions as process information

Record when the signal was issued and when usable material arrived. Classify late responses: no stock, missed collection, incorrect part information, inaccessible location, competing priorities, or inaccurate quantity.

Do not add more cards automatically after every shortage. Extra inventory can conceal a response problem. First establish whether the agreed process was followed and whether its assumptions still fit demand and supply.

Test one loop before expanding

Train operators and material handlers together using a real replenishment cycle. Ask them to show the normal path and explain the exception path. Check the process across shift changes and periods of heavier demand.

Track stockouts, response time, inventory held, and adherence to signal rules. Successful Kanban is less about the appearance of the board and more about whether the authorized work reliably happens when needed.

Related terminology: Lean Enterprise Institute: Kanban.

Continue reading: Plan for Every Part: What a Useful PFEP Should Contain.