Lead Time

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esinanaygun
Posts: 24
Joined: Tue Dec 18, 2012 9:53 am

Lead Time

Post by esinanaygun » Wed Feb 27, 2013 4:54 am

Hi,

I want to find the lead times of a system, but I couldn't find how can I find lead time.In the codings we can find the whole time in system for a part but for example if I have a line like below from A to B and I want to find out the lead times of the products one by one between C and D. Since I couldn't find how to write every single data on a table I can't find out the lead time between C & D.

A-----------------C-----------------------------D------------B

dsturrock
Simio Team Member
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Joined: Thu Mar 13, 2008 12:35 pm
Location: Sewickley, PA USA
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Re: Lead Time

Post by dsturrock » Wed Feb 27, 2013 1:02 pm

I'm not sure if I fully understand what you want.

You can capture any arbitrary statistic with a Tally.
1) Create a TallyStatistic (Definitions > Elements)
2) If you don't already have it, create a state on the entity to store the starting time (ModelEntity > Definitions > States)
3) At the point you want to start collecting the statistic assign TimeNow to your entity state (for example use the State Assignments on a Server)
4) At the point you want to end collecting the statistic record the value of (TimeNow minus your state) to a tally. You could use a Tally step in a process, or simply use the Tally Statistics category on a node.

For your example you might create a state of type real named LeaveCTime and a TallyStatistic named CtoDTime. On C assign LeaveCTime = TimeNow. On the node before D record an observation of (Timenow-LeaveCTime) to TallyStatistic CtoDTime. Although you can customize the categorization and display of your new TallyStatistic, by default I think it usually displays ner the top of your pivot table results.
Dave Sturrock
VP Operations, Simio LLC

esinanaygun
Posts: 24
Joined: Tue Dec 18, 2012 9:53 am

Re: Lead Time

Post by esinanaygun » Thu Mar 07, 2013 3:02 am

Thank You for your answer. But it still doesn't work when the time between the stations are long and the interarrival times are smaller. For example let me put the problem for you like this:
These are my activity points.
A----B---C-----D----E

I am producing a car seat. Where I have the source at point A. The interarrival times must be 2 minutes for a car seat and I have 4 kinds of different seats. The timepath between A and B takes 1 minutes to reach to the point B where I am first combining 10 seats in a pallet. Then from the point B to C I am moving the pallet with a lift truck to point C where I am seperating the items that I combined. Also After the seperation my normal procedure starts. I have 8 different presses in order to make a car seat until point D. Every one of them takes 2 minutes to operate. So my lead time for the first product thinking that I don't have any failures must be 16 minutes. Then the products are packaged at D and E is my sink object. So in this project after I split up the 10 car seats I defined a value which is TallyStart. Then I again defined another Tally which has the name TallyStop. I also said that TallyStart must be TimeNow and for TallyStop it must be TimeNow-TallyStart. But it did not worked.Because everytime a seat is going into the press it is taking the Tally start value and when the first object exits the system, my 10. seat can be in the system which makes the TallyStop a really small value possibly (-). So if we have objects that are really close to each other how can I differ the Lead Time and make a table with the values of each lead time so that I can see the lead times are growing because of the fact that I put 10 seat at once?

Is it better explained now? I hope you can help me out =(

dsturrock
Simio Team Member
Posts: 1453
Joined: Thu Mar 13, 2008 12:35 pm
Location: Sewickley, PA USA
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Re: Lead Time

Post by dsturrock » Thu Mar 07, 2013 12:02 pm

The technique I described is what you want. I'm not sure what you did wrong - perhaps you added the state to the Entity, not the model? Or perhaps did not note that the Tally used units of Time?

Here is an example:
CustomTally.png
CustomTally.zip
You can set the BatchSize in the model properties (right click on Model and select Properties). I configured the model so it generates exactly one batch and processes each entity for exactly 2 minutes just to clearly illustrate the concept. I mark the start time on the path just before Server1 and I tally the custom statistic on entering the node just after Server1.
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Dave Sturrock
VP Operations, Simio LLC

esinanaygun
Posts: 24
Joined: Tue Dec 18, 2012 9:53 am

Re: Lead Time

Post by esinanaygun » Sun Mar 10, 2013 2:42 pm

Ok I did it wrongly I presume. Thanks for the reply...

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