The Toyota Production System (TPS) is based on two core
concepts. The first is the Just-in-Time system, and the second is jidoka, which
can be loosely translated as "automation with a human touch." These
two concepts were discussed above in Part 1.
In order to establish mass production systems, it was
necessary not only to steadily increase production facilities, but also to
streamline production control as well.
Kanban storage area
at Motomachi Plant
In order to establish mass production systems, it was
necessary not only to steadily increase production facilities, but also to
streamline production control as well.
TPS was steadily established and took root through the
introduction of kanban to the existing supermarket style of production in order
to reinforce the efficient Just-in-Time production system.
The kanban, a tool that describes which and how many parts
are used where and when, made just-in-time production possible. The new kanban
management system was adopted at all plants in 1963. By producing parts in
accordance with the instructions on the kanban, parts are delivered among the
different plants only in the volumes needed, and inventories within each
process can be eliminated. As kanban came into widespread use, problems such as
standardization of work and transport management were resolved one after
another and production lines operated smoothly.
Through 1965 kanban were also adopted for retrieving parts
from suppliers. Toyota explained to suppliers that if they adopted the same
techniques as Toyota, they could improve their operations, and companies that
wished to do so steadily introduced TPS. This cooperation resulted in
improvements, and TPS became established as an effective means of producing
mutual benefit for both Toyota and suppliers.
To prevent individual processes from being burdened by
excess personnel or equipment, production items and production volumes were
equalized, that is, production leveling was also implemented. As a result of
achieving level production from assembly lines to the retrieval of materials,
the Just-in-Time system could be implemented on an even higher level.
Andon (engine
assembly line at Kamigo Plant)
If automatic shutdown devices are attached to machines to
automatically stop the machines from operating when abnormalities are detected,
the waste of unknowingly producing defective parts can be eliminated. This is
jidoka of machinery. A further advancement is "management that can be seen
with the eyes." Problem notification devices known as andon boards and
andon lights are installed on each line in positions that are highly visible to
supervisors, and when a problem occurs, andon are lit up-either manually or
automatically so a supervisor can immediately come to the source of the problem
and address it. Andon were installed in the Kamigo Plant in 1966, completing
line automation with a human touch.
In 1966, an online control system was installed at the
Takaoka Plant, making it possible to obtain production instruction information
from terminals installed along the line and perform assembly work. The same
system was also installed at the Motomachi Plant in 1969 and the new Tsutsumi
Plant in 1970 in response to the rapid increase in production volumes and the
expansion of vehicle specifications. However, because production instruction
information could be retrieved from individual terminals, which allowed
down-stream processes to be conducted before they were necessary, the system
led to problems, including the occurrence of numerous assembly errors.
Harigami (c. 1970)
To address these problems, issuing production instructions
from the terminals was terminated and a method of giving production
instructions using sheets attached to the vehicle bodies was adopted.
Production instruction information was obtained from the target of the work
itself, and as a result, advance work assembly errors were eliminated and it
was possible to respond flexibly to changes.
Responding precisely to changes in production volumes
required an increase in availability rates (the percentage of time that
facilities can be operated when operation is desired), and this meant raising
equipment reliability. Accordingly, measures to raise the availability rates of
equipment used in key processes were implemented. For example, at the Kamigo
Plant, personnel from the plant and Production Engineering Division I formed a
countermeasures team to rapidly detect problems and reinforce daily and
periodic inspections on the machining and assembly lines for the T series
engine. The team implemented measures from a variety of perspectives, including
processes and equipment, and achieved a substantial improvement in availability
rates.
Former Executive Vice
President Taiichi Ono
As a result of the advancing of jidoka and other approaches
that came along with the shift to mass production, a problem surfaced in which
a fixed number of workers were needed to operate the equipment, even if
production demand decreased substantially. Having experienced significant
decreases in production demand, Toyota eliminated fixed staff systems to create
production lines that could operate with a small number of workers, in case
production demand dropped, and, through optimal placement of workers, sought to
increase the added value of each worker. Former Vice President Taiichi Ono, who
strived to revive Japan's automotive industry after World War II and who
implemented streamlining of production and established TPS centered on the
principles of Just-in-Time and jidoka, made the following the comments:
“Calls for 'labor-saving measures' started from around 1960
and 1961, but I had always believed that it was necessary to implement
'people-saving' measures that reduced the number of workers needed.
Around the time of the oil crisis, I happened to give a
lecture on labor saving, and later, looking at a summary of the lecture, the
term 'personnel reduction' had been used instead of 'labor saving'. I realized
that someone had hit the point, and I came to believe that personnel reduction
was what would be needed from here on out.
Since production volume was going to decrease, it was
necessary to perform production that had been conducted by seven workers with
just six or even five workers. In other words, it was necessary to create and
innovate facilities and equipment that could be operated by a small number of
workers and manufacture products when production volumes decrease.”
Source: Toyota Motor Corporation
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