Kanban
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Kanban (in kanji 看板 also in katakana カンバン, where "kan 看 カン" means visual, and "ban 板 バン" means card or board) is a concept related to the Lean or Just In Time (JIT) production, but these two concepts are not the same thing. (The Chinese word "kanban" is a common everyday term meaning "sign" or "card" and utterly lacks the specialized meaning which this loanword has acquired in English.) According to Taiichi Ohno, the man credited with developing JIT, kanban is the means through which JIT is managed.
Kanban is a signaling system. As its name suggests, Kanban uses cards to signal the need for an item. Other devices such as plastic markers (Kanban squares) or balls (often golf balls) can also be used to trigger the movement, production, or supply of a unit in a factory.
For example, in the production of a widget, the operator has two shelves, one on either side of the workplace. The raw materials arrive on one shelf and the finished article on the other. These shelves act as kanbans. The outgoing kanban signals the customer's need so that when it is empty, the operator must produce one more widget.
The Kanban is sized so that it can only hold however many the customer needs (usually one). When the operator begins work, he takes the raw material from the incoming kanban, thus signalling to the supplier that he needs more.
Kanban is frequently known as a "pull" system, as everything is pulled in response to past demand. Demand forecasts are not used in kanban systems. This is the opposite of the traditional "push" manufacturing philosophy, in which everything is made to forecasted future needs.
With this in mind, it is not surprising that an important determinant of the relative merits of "push" and "pull" is the quality of the demand forecast. If forecasts are good, then the kanban system will effectively waste useful information, whereas a good "push" system will produce just the right quantities at the right times. In contexts where demand is difficult to forecast, on the other hand, the best one can do is to quickly respond to observed demand. This is exactly what a kanban system does, as a demand signal immediately propagates through the entire chain. "Push" systems often encounter serious difficulties when demand forecasts turn out to be inaccurate.
The Kanban system might be visualised as a "Three bin system" for the brought out parts ( where there is no inhouse manufacturing)- one bin on the factory floor, one bin in the factory store and one bin at the Suppliers' store. The bins usually have a removable card that contains the product details and other relevant information - the Kanban card. When the bin on the shop floor is empty, the Kanban card is removed and given to the store. The store then replaces the bin on the factory floor with a full bin which also contains a removable Kanban card. The store then contacts the Supplier and indicates the need to replenish the Kanban card. The product also containing a Kanban card is delivered into the factory store completing the final step to the system. So it will never run out of product, providing of course, the cards are reliably collected from empty containers. It is a perfect "push-pull" that could also be described as a "loop", providing the exact amount required, with only "one" spare so there will never be an issue of "over-supply". The secret to a good Kanban system is to calculate how many Kanban cards are required for each product. Most factories use the coloured board system (Heijunka Box). This consists of a board created especially for the purpose of holding the Kanban cards.
[edit] For More on the Kanban System See
The term kanban may also be used specifically to describe an embellished wooden or metal sign which has also been reduced to become a trade mark or seal. Since the 17th century, this expression in the Japanese mercantile system has been as important to the merchants of Japan as military banners have been to the samurai. Visual puns, calligraphy and ingenious shapes, or Kanban, define the trade and class of a business or tradesman. Often produced within rigid Confucian restrictions on size and color, the signs and seals are masterpieces of logo and symbol design. For example, a sumo wrestler, symbol of strength, may be used as kanban on a pharmacy sign to advertise a treatment for anemia.
