Quality Consulting
Lean Manufacturing Learning Material
Developments in Lean Manufacturing
Lean
Manufacturing may seem to be a new phenomenon but it is not really especially
new. It is derived from the Toyota Production System or Just In Time
Production, which in turn derived from Henry Ford, the US supermarket
chains and other predecessors.
The history of Lean Manufacturing and Just In Time (JIT) Production goes as far back as the late 1790’s to Eli Whitney and the concept of interchangeable parts.
Early Developments
While Eli Whitney is most famous as the inventor of the cotton gin, the gin is a minor accomplishment compared to his perfection of the concept 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 concerned themselves with individual technologies. During this time our system of engineering drawings developed, modern machine tools were perfected and large scale processes held the centre of attention.
As products moved from one discrete process to the next through the logistics system and within factories, few people concerned themselves with:
- What happened 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. Taylor was a highly controversial
figure in his day and still remains so. He called his ideas Scientific
Management. The concept of applying science to management was sound but
Taylor simply ignored the behavioural sciences and the needs of individuals.
Frank Gilbreth added Motion Study to Scientific Management 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. We now know these as Value Stream Maps.
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 are simply the people who originated the idea of "eliminating waste", a key tenet of JIT and Lean Manufacturing.
The Ford System
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 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. Fords original factory used gravity to keep the vehicle moving as people worked on it, this effectively created single piece flow and the need to have all the relevant components available when the vehicle passed each work station.
Ford's success inspired many others to try and copy his methods. But most of those who copied did not understand the fundamentals of a complete manufacturing strategy. Ford style 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 and people wanted something other than the Model T in black, the Ford system began to break down and Henry Ford refused to change the system. Product proliferation put strains on the Ford system. Annual model changes, multiple colours, and options did not fit well in Ford factories.
At General Motors, Alfred P. Sloan took a more pragmatic approach to production and developed business 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.
The Toyota Production System
Following the Second World War Japanese industrialists started to study American production methods with particular attention to Ford practices and the Statistical Quality Control practices of Ishikawa, Edwards Deming, and Joseph Juran.
At
the Toyota Motor Company, Taichii Ohno and his right hand man, Shigeo
Shingo, began to incorporate Ford production, Statistical Process Control
and other techniques into an approach called the Toyota Production System
or Just In Time. They recognized the central role of inventory in both
managing costs and ensuring high levels of productivity.
The Toyota people also recognized that the Ford system had contradictions and shortcomings, particularly with respect to employees. Toyota soon discovered that factory workers had far more to contribute than just muscle power. This discovery probably originated in the Quality Circle and Continuous Improvement (Kaizan) movement. Ishikawa, Deming, and Juran all made major contributions to the quality movement and the highest award for quality in Japan is still the Deming Award. All this work at Toyota It culminated in the introduction of team based production and cellular manufacturing.
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.
Shingo, at Ohno's suggestion, went to work on the problem of setup and changeover times. Reducing setups to minutes and seconds (SMED) 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 and to some extent it spread to other Japanese companies. When the productivity and quality gains became evident to the outside world, American executives travelled 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 people really understood the underlying principles.
World Class Manufacturing
By the 1980's some American manufacturers, such as Omark Industries, General Electric and Kawasaki were successful with these methods and had started to replicate the productivity and quality levels of the Japanese. Gradually, a knowledge and experience base developed and success stories became more frequent.
Lean Manufacturing
In 1990 J ames Womack and Dan Jones wrote a book called "The Machine That Changed The World". This was a straightforward account of the history of automobile manufacturing combined with a study of Japanese, American, and European automotive assembly plants. What was new was the phrase "Lean Manufacturing."
Lean Manufacturing caught the imagination of manufacturing people in many countries. Lean implementations are now commonplace and the knowledge and experience base is expanding rapidly.
The essential elements of Lean Manufacturing do not substantially differ from the techniques developed by Ohno, Shingo and the people at Toyota. The application in any specific factory does change. Just as many firms copied Ford techniques in slavish and unthinking ways, many firms copy Toyota's techniques in slavish and unthinking ways and with poor results.
There is no simple panacea for manufacturing. Each firm has its own unique set of products, processes, people, and history. While certain principles may be immutable, their application is not. Manufacturing Strategy will always be a difficult, uncertain, and based upon the linking of many individual processes. Strategy is still, largely, an art. But, that should not prevent us from bringing the available science to bear on the problem.
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