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Topic Title: Total Production Lead Time (VSM)
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Created On: 10/26/2017 02:47 AM
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10/26/2017 12:07 PM
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MikelG
Michael Gonzales



Hi!

I am a new member in this group.

I am interested to get other people's thoughts on the Learning To See book particularly on total production lead time. My questions are as follows:

1. Why was the total production lead time calculated by just adding all the inventories (triangle symbol) in between processes and not including the lead time through the process?

2. Should the calculation be: Production Lead Time = lead time through the process + lead time through the inventory triangle?

3. Also, Lead Time (through the process) = WIP x cycle time?

Looking forward to learning from you guys.

Thanks.
10/26/2017 03:17 PM
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MarkRosenthal
Mark Rosenthal



Michael -
The total lead time DOES include the processing time. In the example (on page 29 in my edition) the total processing time is just over 3 minutes, so over the three weeks+ it takes the item to flow through the pipeline, that is pretty trivial. When they are calculating lead time in DAYS, then seconds get buried as rounding.

You #3 is correct - WIP x cycle (meaning the cadence of output) = total lead time.
More specifically, that gives you the lead time if everything flowed FIFO in and out of the queues, etc.
Often things do not, so in the Real World, many items can take considerably longer as others are jumped ahead of them.
10/27/2017 09:44 AM
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MikelG
Michael Gonzales



Thank you , Mark. I was also thinking that it was rounded up so the SECONDS got buried in DAYS.
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