Kanban is a pull system that determines the supply, or production, according to the actual
demand of the customers. In contexts where demand is difficult to forecast the best one
can do is to quickly respond to observed demand. This is exactly what a kanban system
does, it acts as a demand signal which immediately propagates through the entire chain.
"Push" systems often encounter serious difficulties when demand forecasts turn out to be
inaccurate. Where the response cannot be quick enough, e.g. significant lost
sales/downstream production, then stock building may be appropriate by issuing more
kanban. Taiichi Ohno states that kanban must follow strict rules of use,[5] Toyota have six
simple rules, and that close monitoring of these rules is a never ending problem to ensure
that kanban does what is required.
A simple example of the Kanban system implementation might be 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 bin and Kanban card are
returned to the store. The store then replaces the bin on the factory floor with a full bin
which also contains a Kanban card. The store then contacts the supplier and returns the
now empty bin with its Kanban card. The suppliers inbound product bin with its Kanban
card is then delivered into the factory store completing the final step to the system. Thus
the process will never run out of product and 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". This 'spare' bin allows for the uncertainty in supply, use and transport
that are inherent in the system. The secret to a good Kanban system is to calculate how
many Kanban cards are required for each product. Most factories using kanban use the
coloured board system (Heijunka Box). This consists of a board created especially for the
purpose of holding the Kanban cards.
Another example of kanban thinking: in the production of a widget, the operator has two
shelves, one on either side of their workplace. The raw materials can be designated to
arrive on one shelf and the finished articles placed on the other. These shelves can then
be designated to 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 a fixed number of items decided by the
customer needs (usually one). When the operator begins work, he takes the raw material
from the incoming kanban, which when seen by the supplier, signals that the customer
needs one more.
Back
Home Procurement and logistics Energy Production Automation Packaging Outsourcing Articles EMS Kaizen Personal Finance Travel |
KANBAN SYSTEM
