When most people think of kanban they automatically think of kanban cards, probably because the Toyota Production System relies heavily on the use of cards for their signals. But, be aware that many people have strong feelings about the use of cards as signals because of bad experiences with losing the cards or the cards being mismanaged.

What are these mystical items called kanban cards? They are essentially pieces of paper that travel with the production item and identify the part number and amount in the container. The cards can include other information, such as who to call for service or when to take the cards back to the production department. The cards are typically about the size of the old computer punch cards, but they can be any size that works for you. We also recommend that they be brightly colored so that they are easy to spot as they make their way through the process. Figures 5-2 and 5-3 show examples of two kanban cards.