SIM04 · 起源 / 从物料与信息流图到时间梯SIM04 · Origin / From material-and-information flow to the time ladder
一件产品从投料到交付，到底有多少时间在加工？From release to delivery, how much time is this part actually being worked on?
丰田先用“物料与信息流图”把整条价值流画在一张纸上。 年，Mike Rother 与 John Shook 在《Learning to See》中把这套方法带给更多制造企业。下面跟住一件红色工件：四道工序各加工 6 秒，绿色是增值，红色是排队。 Toyota first mapped the full value stream with material-and-information flow diagrams. In , Mike Rother and John Shook brought the method to a wider manufacturing audience through Learning to See. Follow the red part below: each of four operations adds six seconds of processing. Green is value-added work; red is queue time.
🎬 跟住红色工件，看 24 秒加工藏在多少等待里🎬 Follow the red part and see how much waiting surrounds 24 seconds of work
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时间梯 · 绿=加工增值 / 红=排队等待Time ladder · green=processing / red=queueing0.0s
💡 跑完看数据：在制品越多，增值比越低💡 Run it, then read the numbers: more WIP lowers the value-added percentage
三档均跟踪同一件产品走完四站Each mode follows one part through all four stations| 初始在制品Initial WIP / position | 增值时间Value-added | 总周期Total lead time | 增值比Value-added % |
|---|---|---|---|
| 每处 2 件2 at each position | — | — | — |
| 每处 8 件8 at each position | — | — | — |
| 每处 16 件16 at each position | — | — | — |
增值比 = 增值时间 ÷ 总周期。三档都没有加快任何机器，四站增值时间始终是 24 秒；改变的只有红色排队段。Value-added percentage = value-added time ÷ total lead time. No machine runs faster in any mode, so value-added time stays at 24 seconds. Only the red queueing segments change.
🎯 改善顺序🎯 Improvement priority
先砍排队等待，再考虑把机器做得更快。Cut queue time first. Speed up the machine only after that.
⚠ 常见误区⚠ Common mistakes
✗ 提效率 = 让机器更快✗ Better efficiency means faster machines
✓ 先砍等待，增值时间通常动都不用动。✓ Cut waiting first; the processing time often needs no change.
✗ 库存是资产✗ Inventory is an asset
✓ 在制品冻结的是生产周期。✓ WIP locks lead time into the process.
✗ VSM 画完就挂墙上✗ Finish the VSM and hang it on the wall
✓ 画图是为了定下一步先砍哪段等待。✓ The map should identify which waiting segment to remove next.