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The backbone of Toyota Production System is Mechanical Engineering


I was looking at the history of those involved in developing the Toyota Production System. Who were those people, and are there any similarities?

The above list consists of those who impacted the creation of the Toyota Production System. Obviously, this list does not contain all personal. There were hundreds and thousands of people involved. I am confident that this list is missing some critical personals. Not to be biased with my selection, the list contains only names on "Taiichi Ohno's Wikipedia." Yet, the list highlights one crucial trend.


Many have a background in mechanical engineering.


The mechanical engineers developed the Toyota production system. Their views on the operation are like a precise machine that accurately performs its function, maybe like a Swiss watch. The standardized work is the cyclic work that creates a counter-clockwise cycle on the shop floor. These cyclic work connects like gears and forms the continuous flow. The pull system works as the market as a driver.

The backbone of TPS is mechanical engineering.


Definition of "Machine" changed.

This statement that the backbone of TPS is mechanical engineering does sound strange. This is because the Toyota production system claims that people are most important. I am not making a statement against that. I believe that the definition of "machine" has changed by Sakichi Toyoda. Sakichi's auto loom was not just automation. It was automation with human touch & wisdom. He observed his mother suffer from a lousy loom, which developed his interest in creating a better loom. He never intended to treat his mother in the wrong way. Sakichi's loom stopped when there was a problem instead of producing the defect. Ohno gives credit about the "Jidou-ka" concept to Sakichi. Ohno applied such a philosophy on the machine to production organizations. Production should not keep producing defects. Both Sakichi's auto-loom and Ohno's production system aimed to gain productivity. But both never saw humans as subordinate to the machine. They saw that people were in the center of the design of the process. Toyota significantly improved productivity by combining the machines into people's work and keeping them parallel. Machine design that respects humans & humanity became the philosophy of the system.

Here is an example. We, human beings, need to use toilets. So how do we approach this? Many don't even put it into considerations. People need to figure it out by themselves. Some use calculations to solve this problem. But giving any size of allowances will not be enough time for the human to complete the toilet usage when needed. And often, OEE analysis says, "People used bathroom" as the cause of downtime. Isn't this disrespectful to a human? Toyota took a much more straightforward approach. The person who needs to use the toilet will pull the andon. The team leader will replace their position while the individual goes to the bathroom. They shift the gears from normal mode to another and handle the situation. It is a much more human-centric system.


Mechanical engineering, not Industrial engineering.

In his book, "Workplace management," Ohno separates production engineering (shop floor engineering) and industrial engineering. Ideally, both should be one, but he often claims industrial engineering disengages from reality or the shop floor. (Chapter 33) Why? Ohno talks about arithmetic pitfalls (Chapter 6). I believe the same applies to any engineering. Even today, we see some thinking like we should set target cycle time 10~20% below takt time or the goal of OEE is 85%. But these ideas have no scientific reasoning. It is just that based on their experience. These numbers were the reflection of how they view humans. They think that since people make mistakes, giving such margins are "kind" to human. Giving extra time to "deal" with a problem is nice. Toyota approached by adding Andon and help chain. But this "help" was not some random help. There is a specific point where the operator needs to decide if it requires support. The team leader must respond within a particular time. Otherwise, the line will stop, which will trigger Group leaders to respond. It is like shifting gears to emergency mode, giving different dynamics flow during normal and abnormal times.

Please do not take that I discredit industrial engineering. My coach and my father, Hajime Oba, former president of Toyota Supplier Center, have a master's degree in industrial engineering. He accepted the criticism of Ohno and didn't accept any reason to create a gap between theory and reality. He never accepted easy calculations as a solution to a problem. And the truth is that Toyota people never took any science that has the gap between theory & reality. They continue to ask questions about the gap. Once, we visited a metal processing plant. The coach asked why the factory set the temperature 300 degrees above the melting point. I asked if we needed to memorize every element's melting point, and he said no. Yet, he checked the material's melting point since he knows that is basic science. Then, when he visited the shop floor, he saw that the temperature was significantly higher than the melting point, so he wanted a logical explanation. He thought they would save time by adding more heat, but what is the energy cost versus time. Unfortunately, there were no explanations, and we got some opportunities to conduct very meaningful experiments. Especially the TPS people hate "silo" engineers, like product engineering, process engineering, service engineering, etc. They need to know the product engineering to understand their servicing product. Then, everything is an extension of that. Their curiosity is constantly pulling knowledge into its system.


The outlier

There is one clear outlier in the list. His name is Fujio Cho. A guy who graduated from the Tokyo University Law department in Toyota Production System is a mystery. Tokyo University Law department is a mass producer of Japan's bureaucrats. It is the opposite of Kaizen. At that time, Toyota was not a popular place to work. But somehow, such talent came to Toyota. Working on the shop floor with potentially the most complicated engineers is a miracle. Without Mr. Cho, the Toyota production system probably remained the "Ohno method," and it didn't spread as it is today. He helped the organization to define the "laws" of the method. Many have pointed out the importance of diversity when it comes to innovations. The innovation happens with various functions working on the same challenge on the shop floor. (I'm not saying we should mix a lawyer in Kaizen activities.)



When I go to the shop floor, I try to understand the structure and dynamics. I thought like that for years without knowing the background of those who developed the system. Now that I have learned about their experience, I feel more comfortable with my theory.


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