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Toyota Production System – Goodbye to Mass Production – Part 4

Mass Production

Prior to and up to 1950 the total production volume of the Toyota Motor Company was 2685 automobiles.  The most efficient automobile factory in the world, operated by Ford, produced 7000 in a single day. This led Eiji Toyoda, who studied every square inch of that Ford plant, conclude with Taiichi Ohno, that mass production would not work in Japan.

Japan’s situation in the world had changed. The Japanese automobile market was small.  Japan faced an empowered workforce.  The war depleted Japanese business capital and foreign-exchange.  This is the environment that Toyota engineers found themselves in.

You maximize production in Mass Production by never shutting off the assembly line. This leads to two possible outcomes with respect to quality: 1) defective parts are pulled aside to avoid contaminating the population or 2) defects are overlooked. Defects become buried in the product and are difficult to discover later on in the process.

Toyota’s engineers saw something else in this situation also. They saw that defects represented a waste that they could not afford. Mass Production would not work in Japan at that time.

Toyota’s Production System is also famous for innovation. Taiichi Ohno discovered that it is less expensive to produce small batches than large lots. This is based on two phenomena. 1) Small batches result in much less inventory and, 2) If you run off a small amount of parts to assemble into your final product, defects show up right away.


Fords manufacturing requirements were – yield and quality. The yield requirement means that falling below production yields is not acceptable. Workers pass on defects because they believe it will be fixed later in quality areas.  The assembly line just passes the defects downstream. The automobile going down the assembly line with a misaligned part was the correct decision because it did not stop the assembly line or impact the yield. This led to Ford not aggressively chasing down the source of defects.

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