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This is a misunderstanding of lean manufacturing. Lean is not about eliminating every stockpile, it's about thinking through your supply needs and only stockpil

This is a misunderstanding of lean manufacturing. Lean is not about eliminating every stockpile, it's about thinking through your supply needs and only stockpiling what is necessary.

nszceta 5y ago
Were manufacturers stockpiling what was unnecessary before lean manufacturing? It's an absurd notion that anybody would stockpile things without consideration of inventory costs.
- hef19898 5y ago
  They did stockpile everything due to not having a plan or consider costs. That also had the strange side effect of constantly running out of parts. In some way, stuff worked by accidentally having the right stuff on hand at the right time in sufficient quantities. TPS is all about having a plan for this stuff.
- sct202 5y ago
  Sort of, it would come down to suppliers would historically only sell in large quantities to maximize their production efficiency, so the per unit production cost would be minimized by running a long production run. But this would potentially cause scrap if the final product did not sell well to expectations or if there was a design error, and then also increased working capital as the inventory levels would spike really high with infrequent supply from the vendor instead of being more constant with more frequent replenishment. And then multiply across everyone in a supply chain for a single product having to deal with waiting to receive giant parts orders from their vendors before they could start their own giant order to supply their customers.
- Jtsummers 5y ago
  Yes, they were. Think of each stage of the system, not just the components you bring in but also the partially assembled components you produce along the way as well as the finished product. US auto manufactures (in particular) had an operating method where they kept inventories high at all stages. This wasn't entirely deliberate. They weren't saying, "We need 5000 car doors just sitting here." They were, instead, saying, "We can't stop making doors just because everything else down the line is stopped due to <event> so keep churning them out and pile them up." The tail end inventory of "complete" vehicles were sitting there due, often, to quality issues (misaligned assemblies, missing parts, whatever the reason may be). So inventory piles up everywhere along the chain, which also worked because there was a large turnaround period when retooling and equipment downtime (not always planned). Because Nobody Ever Gets Credit for Problems that Never Happened [0] there was an underinvestment in maintenance and improvement efforts. High inventory across the line papers over this issue. Lean discourages high inventory in order to make these issues apparent so that they can get the attention that they deserve. Also, rework is viewed as waste so quality issues should be addressed when they're discovered, not by assembling hundreds or thousands of vehicles incorrectly and then fixing them, fix the assembly line issues causing that misassembly. [0] https://web.mit.edu/nelsonr/www/Repenning=Sterman_CMR_su01_.pdf https://web.mit.edu/nelsonr/www/Repenning=Sterman_CMR_su01_....

This is a misunderstanding of lean manufacturing. Lean is not about eliminating every stockpile, it's about thinking through your supply needs and only stockpiling what is necessary.

nszceta 5y ago

Were manufacturers stockpiling what was unnecessary before lean manufacturing? It's an absurd notion that anybody would stockpile things without consideration of inventory costs.

hef19898 5y ago
They did stockpile everything due to not having a plan or consider costs. That also had the strange side effect of constantly running out of parts. In some way, stuff worked by accidentally having the right stuff on hand at the right time in sufficient quantities. TPS is all about having a plan for this stuff.
sct202 5y ago
Sort of, it would come down to suppliers would historically only sell in large quantities to maximize their production efficiency, so the per unit production cost would be minimized by running a long production run. But this would potentially cause scrap if the final product did not sell well to expectations or if there was a design error, and then also increased working capital as the inventory levels would spike really high with infrequent supply from the vendor instead of being more constant with more frequent replenishment. And then multiply across everyone in a supply chain for a single product having to deal with waiting to receive giant parts orders from their vendors before they could start their own giant order to supply their customers.
Jtsummers 5y ago
Yes, they were. Think of each stage of the system, not just the components you bring in but also the partially assembled components you produce along the way as well as the finished product. US auto manufactures (in particular) had an operating method where they kept inventories high at all stages. This wasn't entirely deliberate. They weren't saying, "We need 5000 car doors just sitting here." They were, instead, saying, "We can't stop making doors just because everything else down the line is stopped due to <event> so keep churning them out and pile them up." The tail end inventory of "complete" vehicles were sitting there due, often, to quality issues (misaligned assemblies, missing parts, whatever the reason may be). So inventory piles up everywhere along the chain, which also worked because there was a large turnaround period when retooling and equipment downtime (not always planned). Because Nobody Ever Gets Credit for Problems that Never Happened [0] there was an underinvestment in maintenance and improvement efforts. High inventory across the line papers over this issue. Lean discourages high inventory in order to make these issues apparent so that they can get the attention that they deserve. Also, rework is viewed as waste so quality issues should be addressed when they're discovered, not by assembling hundreds or thousands of vehicles incorrectly and then fixing them, fix the assembly line issues causing that misassembly. [0] https://web.mit.edu/nelsonr/www/Repenning=Sterman_CMR_su01_.pdf https://web.mit.edu/nelsonr/www/Repenning=Sterman_CMR_su01_....