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Lean
Manufacturing is the latest buzzword in
manufacturing circles. It is not especially new. It comes
from the Toyota Production System
or
Just In Time Production,
Henry Ford and other
predecessors.
Lean
means "manufacturing
without waste." Waste ("muda" in Japanese)
has many forms. Material, time, idle equipment, and inventory are
examples. Most companies waste 70%-90% of their
available resources. Even the best Lean Manufacturers
probably waste 30%.
The
History of Lean manufacturing and Just In Time (JIT)
Production goes back to Eli Whitney and the concept of
interchangeable parts. This article traces the
high points of that history. (Pen Activity)
Early Developments
 While
Eli Whitney is most
famous as the inventor of the cotton gin, the gin was a minor
accomplishment compared to his perfection of interchangeable
parts (parts that can be taken from one product and be
exchanged with another similar product--an example would be
being able to change a light bulb and knowing the new light
bulb will fit because it is made exactly the same as the old
bulb). Whitney developed this idea of interchangeable parts about 1799 when he took a
contract from the U.S. Army for the manufacture of 10,000
muskets at the unbelievably low price of $13.40 each (before
this time, muskets were made individually and the bullets and
parts from one musket would NOT fit in another musket--the
technology did not exist to make parts that were ALL exactly
the same).
For
the next 100 years manufacturers primarily concerned
themselves with technologies. During this time
our system of engineering drawings (blueprints) developed,
modern tools were perfected and large scale processes such as
making steel held the center of attention.
Within the factories of this time,
as products moved from one process to the next, few people
concerned themselves with:
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What happened between
processes
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How multiple processes were
arranged within the factory
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How the chain of processes
functioned as a system.
-
How each worker went about a
task
This changed in the late 1890's
with the work of early Industrial Engineers.
 Frederick
W. Taylor began to look at individual workers
and work methods. The result was Time Study and standardized
work. Taylor was a controversial figure. He called his ideas
Scientific Management.
Frank
Gilbreth co-author of the book (Cheaper By The Dozen) added
Motion Study and invented Process Charting.
Process charts focused
attention on all work elements including those non-value added
elements which normally occur between the "official"
elements.
Lillian Gilbreth brought psychology into the
mix by studying the motivations of workers and how attitudes
affected the outcome of a process. There were, of course, many
other contributors. These were the people who originated the
idea of "eliminating waste", a key tenet of JIT and Lean
Manufacturing.
The Ford System
 And
then, there was Henry Ford.
Starting about 1910,
Ford and his right-hand-man,
Charles
E. Sorensen, fashioned the first comprehensive
Manufacturing
Strategy. They took all the elements of a
manufacturing system-- people, machines, tooling, and
products-- and arranged them in a continuous system (assembly
line) for
manufacturing the Model T automobile. Ford was so incredibly
successful he quickly became one of the world's richest men
and put the world on wheels. Ford
is considered by many to be the first practitioner of Just In
Time and Lean Manufacturing.
Ford's success inspired many
others to copy his methods. But
most of those who copied did not understand the fundamentals.
Ford assembly lines were often employed for
products and processes that were unsuitable for them.
It is even doubtful that Henry
Ford himself fully understood what he had done and why it was
so successful. When the world
began to change, the Ford system began to break down and Henry
Ford refused to change the system.
For example, Ford production
depended on a labor force that was so desperate for money and
jobs that workers would sacrifice their dignity and self
esteem. The prosperity of the 1920's and the advent of labor
unions produced conflict with the Ford system. Product
proliferation also put strains on the Ford system.
Annual model changes, multiple colors, and options did not fit
well in Ford factories.
At General Motors,
Alfred P. Sloan took a
more practical approach. He developed business and
manufacturing strategies for managing very large enterprises
and dealing with variety. By the mid 1930's General Motors
had passed Ford in domination of the automotive market. Yet,
many elements of Ford production were sound, even in the new
age. Ford methods were a deciding
factor in the Allied victory of World War II.
 Ironically,
Henry Ford hated war and refused to build armaments long after
war was inevitable. However, when Ford plants finally retooled
for war production, they did so on a fantastic scale as
epitomized by the Willow Run Bomber plant that built
"A bomber An
Hour."
A Lean Manufacturing Timeline
Click To Enlarge>>
Just In Time and
The Toyota
Production System
After World War II, Japanese
industrialists wanted to know more about how the United States
was able to quickly produce weapons of war (see "A
Bomber An Hour") They studied American production
methods with particular attention to Henry Ford, Ishikawa, Edwards Deming, and
Joseph Juran.
 At
Toyota Motor Company,
Taichii Ohno
and Shigeo Shingo, began to incorporate Ford production and
other techniques into an approach called
Toyota Production System
or
Just In Time .
The
Toyota people also recognized that the Ford system had
flaws, particularly with respect to
employees. Employees at the Ford company
were used mostly for muscle power.
Toyota
soon discovered that factory workers had far more to
contribute than just muscle power. This
discovery probably originated in the Quality Circle movement
(Quality Circles were groups of workers who met together
regularly to discuss how to be more "LEAN".)
Another key discovery involved product variety.
The Ford system was built around a single, never changing
product. It did not cope well with multiple or new products. His
automobiles did not change color or design for years.
 Shingo,
at Ohno's suggestion, went to work on the setup and changeover
problem.
Reducing setups to minutes and seconds allowed
small batches and an almost continuous flow like the
original Ford concept. It introduced a flexibility that Henry
Ford thought he did not need.
All of this took place between
about 1949 and 1975. To some extent it spread to other
Japanese companies. When the productivity and quality gains
became evident to the outside world, American executives
traveled to Japan to study it.
They brought back, mostly, the
superficial aspects like kanban cards and quality circles.
Most early attempts to emulate Toyota failed because they
were not integrated into a
complete system and because
few understood the underlying principles.
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