Канбан система - на английски
Алекси
visual, and "ban " means card or board) is a concept related to
Lean or Just In Time (JIT) production, but these two concepts are not
the same thing. (The Japanese word "kanban" is a common everyday term
meaning "signboard" or "billboard" 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 a means
through which JIT is achieved.[2]
Kanban is a signaling system. As its name suggests, Kanban
historically uses cards to signal the need for an item. However, other
devices such as plastic markers (Kanban squares) or balls (often golf
balls) or an empty part-transport trolley can also be used to trigger
the movement, production, or supply of a unit in a factory.
It was out of a need to maintain the level of improvements that the
kanban system was devised by Toyota. Kanban became an effective tool
to support the running of the production system as a whole. In
addition, it proved to be an excellent way for promoting improvements
because restricting the number of kanban in circulation highlighted
problem areas[3].
Contents
* 1 Origins
* 2 Implementation
* 3 References
* 4 See also
* 5 Further reading
Origins
The term kanban describes an embellished wooden or metal sign which
has often 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.
In the late 1940s Toyota was studying US supermarkets with a view to
applying some of their management techniques to their work. This
interest came about because in a supermarket the customer can get what
is needed at the time needed in the amount needed. The supermarket
only stocks what it believes it will sell and the customer only takes
what they need because their supply is assured. This led Toyota to
view earlier processes, to that in focus, as a kind of store. The
process goes to this store to get its needed components and the store
then replenishes those components. It is the rate of this
replenishment which is controlled by kanban which give permission to
produce. In 1953 Toyota applied this logic in their main plant machine
shop.[4]
[edit] Implementation
With this in mind, it is not surprising that an important determinant
of the relative merits of "push" and "pull" production scheduling is
the quality of the demand forecast. 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. The issue here is 'quickly' respond. 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.