Kanban
Kanban is a visual signaling system that triggers replenishment based on actual consumption rather than forecasts. Originally using physical cards, kanban signals when materials need reordering by making consumption visible. The system maintains lean inventory by pulling replenishment only when needed, rather than pushing based on schedules.
Examples
Two-bin kanban: A workstation has two bins of components. When the first bin empties, production continues from the second while the empty bin signals replenishment. The bin itself serves as the kanban signal, triggering the supplier or stockroom to refill it.
Card kanban: Each container of parts has a kanban card attached. When production begins using a container, the card is removed and sent to the supplier or preceding process, triggering replenishment. The card specifies part number, quantity, and source.
Electronic kanban: Software monitors inventory levels and automatically generates replenishment signals when quantities drop below trigger points. Electronic kanban extends the concept to systems without physical cards.
Definition
Kanban is a key element of lean manufacturing and the Toyota Production System. By tying replenishment to actual consumption, kanban reduces excess inventory, exposes production problems, and creates flow between processes.
Kanban parameters include the number of kanbans in circulation (controlling total inventory), container quantities, and replenishment lead times. Proper sizing ensures adequate material flow while minimizing inventory. Adjusting kanban quantities tunes the system.
Supplier kanban extends the concept to external replenishment. Suppliers receive kanban signals, typically electronic, when customer consumption warrants replenishment. This supports just-in-time supply without reliance on forecasts.
Kanban works best for items with stable, repetitive demand. Highly variable demand, long lead times, or infrequent usage may not suit kanban well. The system requires discipline: every consumption must trigger the signal, and replenishment must respond reliably.
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