The Toyota Production System is a paradox. On the one hand, every activity, connection, and production flow in a Toyota factory is rigidly scripted. Yet at the same time, Toyota's operations are enormously flexible and responsive to customer demand. How can that be?
After an extensive four-year study of the system in more than 40 plants, the authors came to understand that at Toyota it's the very rigidity of the operations that makes the flexibility possible. That's because the company's operations can be seen as a continuous series of controlled experiments. Whenever Toyota defines a specification, it is establishing a hypothesis that is then tested through action. This approach — the scientific method—is not imposed on workers, it's ingrained in them. And it stimulates them to engage in the kind of experimentation that is widely recognized as the cornerstone of a learning organization.
The Toyota Production System grew out of the workings of the company over 50 years, and it has never actually been written down. Making the implicit explicit, the authors lay out four principles that show how Toyota sets up all its operations as experiments and teaches the scientific method to its workers. The first rule governs the way workers do their work. The second, the way they interact with one another. The third governs how production lines are constructed. And the last, how people learn to improve. Every activity, connection, and production path designed according to these rules must have built-in tests that signal problems immediately. And it is the continual response to those problems that makes this seemingly rigid system so flexible and adaptive to changing circumstances.
The Experiments Of The Toyota Production System
When organizations are managed according to the four rules, individuals are repeatedly conducting experiments, testing in operation the hypotheses built into the designs of individual work activities, customer-supplier connections, pathways, and improvement efforts. Click here to see a summary of the hypotheses, the way they are tested, and the response if they are refuted.