It looks like manufacturers in general and the automobile industry in particular, are taking a few steps back from just-in-time manufacturing.  It appears that they have discovered that the system where they accumulate little or no inventory may save a few bucks, but when it breaks, it gets ugly fast:

Toyota Motor Corp. is stockpiling up to four months of some parts. Volkswagen AG is building six factories so it can get its own batteries. And, in shades of Henry Ford, Tesla Inc. is trying to lock up access to raw materials.

The hyperefficient auto supply chain symbolized by the words “just in time” is undergoing its biggest transformation in more than half a century, accelerated by the troubles car makers have suffered during the pandemic. After sudden swings in demand, freak weather and a series of accidents, they are reassessing their basic assumption that they could always get the parts they needed when they needed them.

“The just-in-time model is designed for supply-chain efficiencies and economies of scale,” said Ashwani Gupta, Nissan Motor Co.’s chief operating officer. “The repercussions of an unprecedented crisis like Covid highlight the fragility of our supply-chain model.”

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The basic idea of just in time is avoiding waste. By having suppliers deliver parts to the assembly line a few hours or days before they go into a vehicle, auto makers don’t pay for what they don’t use. They save on warehouses and the people to manage them.

But as supply chains get more global and car makers increasingly rely on single suppliers, the system has grown brittle. The crises are more frequent.

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A freak snowstorm in Texas in mid-February shut down a refinery that feeds production of 85% of resins produced in the U.S. Those resins go into components from car bumpers to steering wheels. They’re some of the least expensive raw materials in a car, but they go into seat foam, and dealers can’t sell a car without seats.

At the end of March, Toyota shut down production at several U.S. plants due to the shortage, according to a schedule seen by The Wall Street Journal, hitting production of some of its bestsellers, including the RAV4 sport-utility vehicle. 

Obviously, excessive inventory can be as much of a problem as not enough, but when you have inventory levels that are measured in hours, as opposed to weeks, when something goes wrong, you are completely f%$#ed.