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The
word Kan means "card" in Japanese and the
word "ban" means "signal". So Kanban
refers to "signal cards".
What
are signal cards?
Here's
how Kanban works:
Let's
say one of the components needed to make widgets is
a 42" stem-bolt and it arrives on pallets. There
are 100 stem-bolts on a pallet. When the pallet is empty,
the person assembling the widgets takes a card that
was attached to the pallet and sends it to the stem-bolt
manufacturing area. Another pallet of stem-bolts is
then manufactured and sent to the widget assembler.
A
new pallet of stem-bolts is not made until a card is
received.
This
is Kanban, in it's simplest form.
A
more realistic example would probably involve at least
two pallets. The widget assembler would start working
from the second pallet while new stem-bolts were being
made to refill the first pallet.
If
this was a high volume widget manufacturing facility,
each widget assembly station might empty a pallet of
stem-bolts in just a few minutes, and there could be
15 or 20 widget assembly stations. Thus there would
be a continual flow of cards going back to the stem-bolt
manufacturing area that would cause a continual flow
of pallets of stem-bolts to be sent to the widget assembly
stations.
Kanban
is Pull (Demand)
This
is called a "pull" type of production system.
The number of stem-bolts that are made depends on the
customer demand--in other words the number of cards
received by the stem-bolt manufacturing area.
Systems
other than cards may be used. For example, the empty
pallets may be returned to the stem-bolt manufacturing
area. Each empty pallet received indicates a need to
manufacture 100 more stem-bolts. For other types of
components, bins, boxes or cages might be used instead
of pallets. Or components might be stored on shelves
in the widget assembly area. When a shelf became empty
that signals that more components need to be manufactured
and the shelf refilled.
In
Kanban the method of handling the components is flexible,
and depends on the needs of the manufacturing process.
An
Alternative Kanban Model
Kanban
can also operate like a supermarket. A small stock of
every component needed to make a widget would be stored
in a specific location with a fixed space allocation
for each component. The widget assemblers come to the
"supermarket" and select the components they
need. As each component is removed from the shelf, a
message is sent to a "regional warehouse"
or component manufacturing facility, requesting that
the component be replaced. The "supermarket"
might then receive a daily shipment of replacement components,
exactly replacing those that were used.
If
we just change the term "supermarket" to "warehouse"
we have our manufacturing example.
This
"supermarket" model is different from the
first Kanban example in that it would be used when components
are manufactured in facilities that are distant from
the widget assembly plant. Instead of moving around
small quantities of components, larger quantities are
shipped once a day to the centralized warehouse.
Kanban
- Responsive To Customers
Kanban
results in a production system that is highly responsive
to customers. In the above example, the production of
widgets will vary depending on customer demand. And
as the widget demand varies, so will the internal demand
for widget components. Instead of trying to anticipate
the future (predicting the future is difficult) , Kanban
reacts to the needs.
Kanban
does not necessarily replace all existing material flow
systems within a facility. Other systems such as Materials
Requirement Planning (MRP) and Reorder Point (ROP) may
remain in operation. Kanban is most beneficial when
high volume/low value components are involved. For low
volume and high value components, other materials management
system may be a better option.
JIT
- Just In Time / Continual Improvement
Kanban
is directly associated with Just-In-Time (JIT) delivery.
However, Kanban is not another name for just-in-time
delivery. It is a part of a larger JIT system. There
is more to managing a JIT system than just Kanban and
there is more to Kanban than just inventory management.
For
example, Kanban also involves industrial re-engineering.
This means that production areas might be changed from
locating machines by function, to creating "cells"
of equipment and employees. The cells allow related
products to be manufactured in a continuous flow.
Kanban
involves employees as team members who are responsible
for specific work activities. Teams and individuals
are encouraged participate in continuously
improving the Kanban processes and the overall production
process.
Kanban
is not a system indented to be used by itself. It is
an intregal part of Kaizen
and 5S.
Introduction
to Kanban article by: Steve Hudgik
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