Shigeo Shingo is perhaps a lesser known quality guru in the West, although his impact on Japanese industry, and less directly Western industry, has been very large. To quote Norman Bodek, President of Productivity Incorporated:

If I could give a Nobel prize for exceptional contributions to the world economy, prosperity and productivity, I wouldn’t have much difficulty selecting a winner – Shigeo Shingo’s life work has contributed to the well being of everyone in the world. Along with Taiichi Ohno, former Vice President of Toyota Motors, Mr Shingo has helped revolutionise the way we manufacture goods. His improvement principles vastly reduce the cost of manufacturing – which means more products to more people; they make the manufacturing process more responsive while opening the way to new and innovative products, substantially reduce defects and improve quality, and give us a strategy for continuous improvement through the creative involvement of employees.

(Foreword to The Sayings of Shigeo Shingo, English translation

by Andrew P Dillon, Productivity Press 1987)

Shingo’s approach emphasises production rather than primarily management, His motto is that Those who are not dissatisfied will never make any progress. He believes in achieving careful thought, pursuit of goals, planning and implementation of solutions.

By 1954 he had investigated 300 companies. In 1955 he took charge of industrial engineering and factory improvement training at Toyota Motor Co for both its employees and part suppliers (100 companies).

During the period 1956-58 at Mitsubishi Heavy Industries in Nagasaki, Shigeo Shingo was responsible for reducing the time for hull assembly of 65,000 ton super-tankers from 4 months to 2 months. This established a new record in shipbuilding and the system spread to every shipyard in Japan.

It was in the period 1961-64 that Shigeo Shingo extended the ideas of control to develop the Poka-Yokemistake-proofing or Defects=0 concept. Subsequently the approach was successfully applied at various plants with records of over 2 years totally defect-free operation being established.

In 1968 at the Saga Ironworks he originated the Pre-Automation system which later spread throughout Japan. He was awarded a Yellow Ribbon Decoration for his distinguished services in improving production in 1970. Also in that year he originated the SMED System at Toyota (Single Minute Exchange of Die) which is part of the Just-in-Time system.

Shingo has written more than 14 books, with a total by 1981 of more than 350,000 copies sold. Several have been translated into English and other European languages, especially his book on the Toyota Production System.

Shingo’s message

In terms of quality, Shingo’s paramount contribution could be taken to be his Poka-YokeDefect=0 or literally mistake-proofing concept. The basic idea is to stop the process whenever a defect occurs, define the cause and prevent the recurring source of the defect.

No statistical sampling is therefore necessary. A key part of this procedure is that source inspection is employed as an active part of production to identify errors before they become defects. Error detection either stops production until the error is corrected, or it causes adjustment to prevent the error from becoming a defect. This occurs at every stage of the process by monitoring potential error sources.

Thus defects are detected and corrected at source, rather than at a later stage. Typically, this process is made possible by machines with immediate feedback; human personnel are avoided as they are fallible. They are essential, however, to establish the potential error sources. Having learned about and made considerable use of statistical quality control in his 40s, it was some 20 years later in 1977 that Shingo was finally released from the spell of statistical quality control methods when he saw with his own eyes how the Shizuoka plant of Matsushitas washing machine division had succeeded continually for one month with zero defects on a drain pipe assembly line involving 23 workers.

This was achieved principally through the installation of Poka-Yoke devices that prevented defects from occurring. He argues that zero defects can be achieved in this way by using source inspection and the poka-yoke system. Together they constitute Zero Defects Quality Control.

This concept of zero-defects, however, is somewhat different from that usually attributed to the American guru, Philip Crosby. The concept emphasises the achievement of zero defects by good engineering and process investigation, rather than an exhortation/slogan emphasis that has been associated with the quality campaigns of many American and Western companies. Shingo himself, like Deming and Juran, shows concern at such American approaches, arguing that posting defect statistics is misguided, and that instead the defective elements in operations that generate a lot of defectives should be hunted down.