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Topic Title: Calculating the system Lead time.
Topic Summary: Building a VSM
Created On: 11/27/2009 10:35 AM
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11/30/2009 10:26 AM
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208154
Damian Besozzi



Hi,

I am building the value stream mapping for one of the process of the company I work for and I am stuck because of the following doubt:

One of the products we manufacture involves mixing (following a recipe) three different raw materials in a reactor in order to get the final product. After a quality control, the product is sent to the packaging machine so that it could be stored in five liter containers.
The point is which of the three different raw materials I have to consider so that I could calculate the lead time of the whole process.

Thanks in advance for your answers.
Regards,
Damián.
12/02/2009 09:11 AM
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Tizzo
Jason Tisbury



Hi Damian,
When mapping any value stream you need to consider all of the raw materials being consumed. When all are considered, the one with the longest lead time will have the greatest impact on the total lead time. By considering (and measuring) all of the raw materials you won't fall into the trap of making assumptions.

Cheers,
Jason.
12/02/2009 09:12 AM
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GTJones
Gary Jones



Hi Damian

To answer your question you need to think about the Theory of Constraints - which of the Raw Materials is your constraint?

As an example if two of the materials are common (used in other products) and one is unique you could treat that as your constraint? assuming that the other materials do not constrain the process? The other view is to look at each materials lead time - stock cost and replensihment profile (Runner - Repeater or Stranger)

So like all problems there are a number of solutions the right one is the one that works for you :-)

Hope that helps

Gary



Originally posted by: 208154

Hi,



I am building the value stream mapping for one of the process of the company I work for and I am stuck because of the following doubt:



One of the products we manufacture involves mixing (following a recipe) three different raw materials in a reactor in order to get the final product. After a quality control, the product is sent to the packaging machine so that it could be stored in five liter containers.

The point is which of the three different raw materials I have to consider so that I could calculate the lead time of the whole process.



Thanks in advance for your answers.

Regards,

Damián.
12/04/2009 03:41 PM
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leanwannabe
Brian Koenig



This won't directly answer your question, but are you calculating lead-time from the customer's point of view or cumulative processing time of the final product?

Also, are you utilizing buffers to offset instabilities in the system? If the buffers are adequate and you are only calculating the lead time from the customer's point of view, the lead time for the raw material would be insignificant. Even though a waste analysis might determine you are carrying too much inventory (muda).

If you are calculating cumulative processing lead time this could be influenced by a combination of the raw material lead time, buffers on hand and also backlog of orders in que. The mix raw material lead time can possibly be negated as a contributing factor to cumulative lead time due to overlap with other processing steps, their buffers, raw material lead times and order ques.

Feel free to respond if you'd like any clarification. Good luck.
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