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After adding the red bin at the end, we saw defects being caught there—so fewer bad items reached the customer. But we also saw that lots of defects were still being created at every station. We were reacting at the end rather than preventing problems at the source. Workers didn't have a shared idea of "good" or how their step could cause a defect.
Quality is built in at the process, not only inspected later. So we invest in training: workers learn what "good" looks like and what causes defects at their station. We train them at their stations (off the live line where needed) and show how their work affects the final product. That lowers the defect rate. We also add red bins at every station: workers can now identify defective pieces and put them in the red bin so those items leave the value stream. Same number of people, but now they can see and stop defects where they're created.
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