Historia lean manufacturing

Lean Manufacturing is the latest buzzword in manufacturing circles. It is not especially new. It derives from the Toyota Production System or Just In Time Production, Henry Ford and other predecessors.
The lineage 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 long history.Early Developments

Eli Whitney is most famous as the inventor of the cotton gin. However, the gin was a minor accomplishment compared to his perfection of interchangeable parts. Whitney developed this 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.
For the next 100 years manufacturers primarily concernedthemselves with individual technologies. During this time our system of engineering drawings developed, modern machine tools were perfected and large scale processes such as the Bessemer process for making steel held the center of attention.
As products moved from one discrete process to the next through the logistics system and within factories, few people concerned themselves with:
• Whathappened between processes
• How multiple processes were arranged within the factory
• 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. Taylorwas a  controversial figure. He called his ideas Scientific Management. The concept of applying science to management was sound but Taylor simply ignored the behavioral sciences. In addition, he had a peculiar attitude towards factory workers.
Frank Gilbreth (Cheaper By The Dozen) added Motion Study and invented Process Charting. Process charts focused attention on all work elements includingthose 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 FordSystem

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 for manufacturing the Model T automobile. Ford was so incredibly successful he quicklybecame 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 evendoubtful 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 theadvent 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 pragmatic approach. He developed business and manufacturing strategies for managing very large enterprises and dealing with variety.  By the...