4 ms·
I feel like i have to repeat this very often: if a single traffic jam or other predictable common-cause variation results in your JIT implementation costing "fa
by kqr 4y ago
I feel like i have to repeat this very often: if a single traffic jam or other predictable common-cause variation results in your JIT implementation costing "far in excess of inventory savings" all you're telling me is that you have a really shitty JIT implementation.
JIT means having the buffer on hand to handle at the very least common-cause variation. But it also should come with the flexibility to handle variation of assignable causes at a reasonable cost.
Critically, you can't just press delete on all your inventory and then call it JIT. You have to adapt your processes for it, work with local authorities for improvements to infrastructure, and then always keep a larger buffer than you think you need.
JIT is not about deleting inventory. It's about reducing variation in your processes until most of your inventory truly becomes useless.
When you have a good JIT implementation, you are more flexible to take advantage of changing external conditions, not less.
- salawat 4y agoYou've now redefined JIT to mean "buffered with the minimum viable buffer" where minimum viable buffer is "whereever I drop the goalposts when defining common-cause variation. It's the definitional version of working out a variable in an equation, making a mistake, and ending up looking at 0=0. Happens all the time.
- kqr 4y agoYes, but that it literally what JIT means, though. It's a mindset of solving assignable-cause variation at its cause rather than papering over it with more inventory.
- jeffreygoesto 4y agoLiterally, "just" in time would mean "not more (material, goods,...) than needed" in time, wouldn't it? A real world analogy to Kanban.
- kqr 4y agoKanban is indeed one way to do just in time. It's useful primarily for the more variable flows. For more regular flows, you can often rely on the average flow rate working out and schedule deliveries in advance.
- marcosdumay 4y agoJIT is mostly a name for inter-companies Kanban (the factory version of Kanban, not the software one). And because of that, yes, the amount of inventory is pretty much arbitrary.
- kqr 4y agoThis is a common misconception. People often talk about the kanban style JIT because it looks impressive, in some sense. There's all these things going back and forth. But as Taiichi Ohno himself would tell you: if it looks impressive, it's wasteful. It's a lot of motion with little movement. Efficiency looks disappointingly obvious and simple. Kanban is a necessary evil when you have been unsuccessful in driving out variation, it's not a desirable state of things.
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- brookst 4y agoYes? My point was that people get carried away with maximizing optimizations because they start measuring the degree of optimization rather than the ultimate goal. I’m not saying JIT always goes wrong, any more than neural net training always goes wrong. Just that when it does, it is often because an overzealousness that leads to a disconnect between the local and global goals.