Reddit reviews The Machine That Changed the World: The Story of Lean Production-- Toyota's Secret Weapon in the Global Car Wars That Is Now Revolutionizing World Industry

If you want to understand where Tesla is going wrong in their manufacturing and how it manifests itself as panel gaps and other assorted defects, then I can't recommend enough The Machine That Changed the World by Womack & Jones. Fantastically illuminating, this book details the rise of Toyota's lean production philosophy as opposed to GM/Ford's mass production process. It's not a dry book, whatsoever, it's a riveting read, first published in 1990 based upon a 5-year $5 million study done by MIT on the state of automobile manufacturing.

Tesla uses a few lean production principles, but in many ways -- from the outside looking in -- it appears as though they are stuck implementing the sames 1980s mass production principles that caused the U.S. automobile manufacturers to stumble and lose dramatically to Japanese manufacturers like Toyota.

Here's a few juicy tidbits from the book that contrast lean production vs. mass production.

Mass production mentality:

> Managers are headquarters generally graded factory management on two criteria -- yield and quality. Yield was the number of cars actually produced in relation to the scheduled number [...]. Factory managers knew that falling below the assigned production target spelled big trouble, and that mistakes could, if necessary, be fixed in the rework area, after the end of the line [...]. Therefore, it was crucial not to stop the line unless absolutely necessary. Letting cars go on down the line with a misaligned part was perfectly okay, because this type of defect could be rectified in the rework area, but minutes and cars lost to a line stoppage could only be made up with expensive overtime at the end of the shift. Thus was born the "move the metal" mentality of the mass-production auto industry.

Sound familiar? Management by production target causing a move-the-metal mentality... which causes assembly line workers to let defective parts and misaligned installation continue on through the line.

Ohno -- the architect of lean production -- understood why this was a problem:

> [Ohno] reasoned that the mass-production practice of passing on errors to keep the line running caused errors to multiply endlessly. Every worker could reasonably think that errors would be caught at the end of the line and that he was likely to be disciplined for any action that caused the line to stop. The initial error, whether a bad part of a good part improperly installed was quickly compounded by assembly workers farther down the line. Once a defective part had become embedded in a complex vehicle, an enormous amount of rectification work might be needed to fix it. And because the problem would not be discovered until the very end of the line, a large number of similarly defective vehicles would have been built before the problem was found.

And so he sought to rectify it with a lean production principle:

> When a worker found a defective part, he [...] carefully tagged it and sent it to the quality-control area in order to obtain a replacement part. Once in quality control, employees subjected the part to what Toyota calls "the five why's" in which [...] the reason for the defect is traced back to its ultimate cause so that it will not recur.

Every worker was also allowed and encouraged to stop the entire assembly line if they found a problem that needed to be corrected. Then all the workers would seek to rectify the issue such that it never happens again.

This philosophy causes growing pains. Toyota experienced constant line stoppage at the initial outset of their lean implementation. But since you address the root cause of every problem, eventually the line begins to become more reliable. So reliable, in fact, that Toyota was able to operate at 100% uptime in short order.

Most companies give up during the initial growing pains phase because it feels like you're not producing efficiently.

The proof is in the results though. With mass production you get:

> [...] the best evidence of old-fashioned mass production: an enormous work area full of finished cars riddled with defects. All these cars needed further repair before shipment, a task that can prove enormously time-consuming and often fails to fix fully the problems now buried under layers of parts and upholstery.

While lean production experiences:

> At the end of the line, the difference between lean and mass production was even more striking. At Takaoka, we observed almost no rework area at all. Almost every car was driven directly from the line to the boat or the trucks taking cars to the buyer.

Of course, lean production has many principles and philosophies, but when it comes to the assembly line itself and manufacturing it has two high-level features:

> The truly lean plant has two key organizational features: It transfers the maximum number of tasks and responsibilities to those workers actually adding value to the car on the line, and it has in place a system for detecting defects that quickly traces every problem once discovered, to its ultimate cause.

Once you finish reading this book, it should be easy to understand where Tesla lacks manufacturing maturity. I'm a huge Tesla fan. And I can only hope that they eventually fix all these problems. It's difficult for me to watch from the outside looking in.