Kanban Card Cycle
What triggers the start of a kanban card cycle?
A downstream consumption event empties a container or reaches the predefined reorder point; the card is then released as the replenishment signal.
What does the card actually authorize?
It authorizes movement, production, transfer, or purchase of a specific replenishment quantity tied to the kanban loop and container standard.
How is cycle timing determined?
Cycle timing is determined by daily demand, replenishment lead time, safety factor, and container size; these variables determine the number of kanbans required to keep the loop stable.
The kanban card cycle is the repeating pull-replenishment loop in which a kanban card travels with or is detached from a container to signal that consumed material must be replenished by an upstream process, warehouse, or supplier. It starts when downstream consumption empties a container, releasing the card to authorize production, movement, or purchase of a replacement quantity.
On an assembly line, the kanban card cycle operates through a parts supermarket stocked with standardized totes of fasteners, brackets, or machined components. When an operator empties a tote, the detached card becomes the replenishment signal for internal logistics, triggering transport from warehouse or production upstream. Each card is tied to a specific part number, container quantity, replenishment source, and lead time, so the system replaces only what has actually been consumed. The same card circulates through fixed statuses such as empty, full, and wait between demand and supply sources. This closed loop supports just-in-time flow, prevents uncontrolled overstock, and gives line-side inventory visible authorization for each container. Warehouse teams stage and return containers in sequence, and the number of cards is sized to lead time and demand to keep the loop stable.
Card loss or misrouting: When a card is detached, damaged, or sent to the wrong loop, the replenishment signal disappears, so the downstream cell starves even though inventory exists elsewhere in the plant.
Incorrect kanban sizing: If lead time, container quantity, or safety factor is set too low, cards circulate too slowly, causing stockouts; too high, the system overbuilds buffer and defeats lean control.
Process mismatch at receiving: If receiving does not scan, stage, or return containers in correct sequence, the card cycle breaks, delaying replenishment and causing bottlenecks in internal logistics.