Is it possible to simulate a realistic changeover?

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Marcos MNA asked Dec 16, '20 Ben Wilson commented Jan 4, '21

Is it possible to simulate a realistic changeover?

I want to simulate a realistic changeover/setup time from one type of item to another one. I want a processor to start its changeover/setup time once it has processed the last piece of one type of item, instead of waiting until receiving the first piece of the new type of item which will be processed. I have quality controls with probability functions between processors so it is not as simple as counting how many items have been processed... But I would appreciate it you explain me how to do it in that way as well. I am sorry for asking so much about it but I need to finish my work on it and I am quite desperate with it. Thank you very much for your help!

Software Version:

FlexSim 20.2.0

flexsim 20.2.0 setup time simulate changeover

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Ben Wilson ♦♦ commented · Jan 04, 2021 at 03:20 PM

Hi @Marcos MNA, was Parker S's or marcello.rosadini's answer helpful? If so, please click the red "Accept" button on one of their answers. Or if you still have questions, add a comment and we'll continue the conversation.

If we haven't heard back from you within 3 business days we'll auto-accept an answer, but you can always unaccept and comment back to reopen your question.

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Answer 1 · 2020-12-16T18:22:09Z

Parker S answered Dec 16, '20 Jason Lightfoot commented Dec 28, '20

@Marcos MNA

There are multiple ways to simulate a changeover. Unfortunately, every model is different and might require a specific process flow to do the changeover correctly. The more complicated your model is, the more complicated your changeover will be.

One way that I have used is a Wait for Event activity that triggered when the inventory queue hit zero. The InventoryQueue contained all items in the first batch of inventory.

After this fired, I acquired the operator at that workstation and had a Delay activity signifying the changeover time then released the operator.

Here is a model that shows a changeover using a Global Variable as a counter.

support_ChangeoverCounter.fsm

Once the counter gets to a certain value, the changeover fires. The process flow also shows how to use custom code activities to close/open the ports and change the state of the processor.

I hope this gives you some ideas on how you might create a changeover in your model, good luck!

1608139285806.png (19.4 KiB)

support-changeovercounter.fsm (35.1 KiB)

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Parker S ♦ commented · Dec 16, 2020 at 09:47 PM

This model shows how you could do the changeover using the counter with the quality controls activated.

support_prueba.fsm

Notice the triggers on Queue1 that acts as the counter and sets a number label on the item that will not change if it is reworked. You will need to include activities to set the processor state and close/open ports as shown in my previous model. You will also need to duplicate the process flow for each processor and reset the counter if you have more than one changeover.

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support-prueba.fsm (53.4 KiB)

Parker S ♦ Parker S ♦ commented · Dec 18, 2020 at 04:21 PM

@Marcos MNA

Have you seen my reply above? Let me know if this works for you.

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Marcos MNA Parker S ♦ commented · Dec 22, 2020 at 07:27 PM

Thank you very much @Parker S for your answers! I have to go over about how to create Process Flow because I am new using this software and need to check how to link 3D model with Process Flow. I will try to create my model with the advices you gave me and for sure I will ask you a few more questions if you do not mind.

By the way, in the second model you attached (support-prueba.fsm), I do not see a "changeover time" in the Dashboard charts. When Processor1 processes the item number 48, it starts its setup time, not the changeover time as it did in the first model you attached (support-changeovercounter.fsm). How can I solve it? I try to copy-paste the code you include in the first model into the second one just for Processor1 and it is not working. And I also do not know, if it works, how I could include the percentage of the quality control points to the Process Flow-

If I have more than one changeover, when should I reset the counter?

And is it possible to send an item out of the line to a sink if it is the item number 48 for example of my batch?

Thank you again!

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Marcos MNA Marcos MNA commented · Dec 22, 2020 at 08:23 PM

Here it is a picture of the problem I told you above about I can not see the "changeover time"

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1608668620760.png (56.6 KiB)

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Answer 2 · 2020-12-16T17:20:20Z

Marcello Rosadini answered Dec 16, '20 Marcos MNA commented Dec 16, '20

It is hard to tell without having a look at your model or fully explaining the problem.

You need to define a clear criteria that will trigger the beggining of the setup time. This is part of the design of your logic. Once you have this, translating it into the proper sintax should be easy.

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Marcos MNA commented · Dec 16, 2020 at 08:37 PM

I attach now the model. There are two quality controls (now there are deactivated) after Processor 2 and Processor 4, and I want processors to start their setup time as soon as they can, after they have processed the last item of the previous type of item. If you run the simulation, you will see so much idle time in Processor 2, 3 and 4 while they are waiting the second time of item to arrive to them. I think I could use the solution @Parker S suggested if I do not use the quality controls but I do not know how to do it if they are working.

Prueba.fsm

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prueba.fsm (48.3 KiB)

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