“Can a pull system with zero stock make the company more fragile? Sure it can, that’s the whole point: fragile, but flexible. The pull system doesn’t make the company fragile: it reveals the weak points. Top performance is about keeping a ball on top of a round hill it needs everybody’s engagement to make sure it stays there.”
Pull systems don”t have zero stocks, but low stocks, and the experience of disasters — from the Mississippi flood of 1993 in the US, to the Aisin Seiki fire of 1997 and the Fukushima earthquate of 2011 in Japan — has shown Toyota’s pull system to be robust and able to recover much faster than anyone expected, including the Japanese press.
“Fragility is strength” is a cute paradox, but not applicable here. The true paradox is that stocks generally do not protect you against shortages. They do for crude oil and similar commodities, but not for the thousands of different items you need in manufacturing. You end up with full warehouses that are somehow out of the item you need today.
What protects you more effectively is the combination of low stocks with the kind of vigilance that makes you reserve all the available trucking in Chicago a few days before a flood, as Toyota did in 1993. A pull system supports the vigilant monitoring of stocks in two ways:
- Self-adjustment in the speed of circulation of pull signals automatically absorbs the routine fluctuations in volume and mix.
- When major disruptions occur, they are quickly detected and acted on.
See on www.scdigest.com