How to Do Value Stream Mapping – Lesson 6 – The Time Ladder

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# Here the transcript of the video

In this video, I will explain to you the last element of the Value Stream Map. The Time Ladder.

At this stage of the Value Stream Map, you should have the Material Flow at the bottom and the Information Flow on the top.

The time ladder has to be drawn under the process boxes and the inventory triangle with the rules I will tell you in a few seconds.

The ladder has to be drawn with the highest part under the triangle and lowest part under the process boxes.

Once the ladder is drawn you have to put Value Added Time and Lead Time on that.

What is the Value Added Time?

Typically, the value-added time is defined as the time the customer is willing to pay for.

What is Lead Time?

Typically, the Lead Time is defined as the time one piece it takes one part to pass through one operation.

There is a lot to say about these definitions and I will treat it into details in other videos.

How to Calculate the Value Added Time?

To be balanced between effort and accuracy you can assume that the Value Added Time of a process box is equal to the Cycle Time of the operation.

How to calculate Lead Time?

Even here, to have a good estimation you can take the pieces of inventory you have seen during the Gemba Walk and divide by the customer demand.

For example,

You have 100 pieces under the triangle and the customer demand is 20 pieces a day. In this case, the Lead Time is 5 Days.


You have to fill all the spaces of the time ladder and then do the sum of the Value Added Time and the Lead Times.

Typically you will find something like:

5 hours of Value Added Time and 25 days of Lead Time.

This means that a piece has to wait 25 days to be completed even if the processing time is only 5 hours.

This a ratio of 2,5% between Value Added and Lead Time!

Quite Shocking. Is not it?

Record the Time Information, the date, and the name of the team and you will have your first value stream map complete!

What I have explained to you so far are the steps to create the Current State Value Stream Mapping. In the next video, I will explain to you how to start creating the future state Value Stream Mapping.

#LeanVlog #Value_Stream_Map #Time_Ladder

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