Two types of products going into one processor

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Harish G asked Mar 14, '22 Harish G commented Apr 4, '22

Two types of products going into one processor

Hello everyone,

I am stuck with a problem which involves 2 types of products from separate sources which goes through inspection and then to the same rack, where it cures for 4 hrs, from where it goes into the processor, through to the queue where it accumulates in batch of 4 before it is dispatched.

The following are the constraints which I am figuring out how to add into the model:

1. Eg: When the PalletMB1 is empty, the processor should evaluate if pulling more of same type1 will be able to produce a full batch of 12, coz we don't want partial batches. If it can't, then it should switch to pulling Type 2 product from the rack and do the same evaluation. If both types can't result in full batch, the model should stop the processor and start filling the rack to full with both product types and then continue this.

2. There is a changeover time of 15 minutes at the processor, when it switches from on type to another. So, in order to minimize this it should run type 1 parts completely before switching to type 2, satisfying the above constraints.

Please see attached the model image for your reference. Thanks for your kind help!

Software Version:

FlexSim 22.1.0

questions flexisim

1647277641338.png (184.8 KiB)

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Ryan Clark commented · Mar 22, 2022 at 06:37 PM

Hi @Harish G, was one of Harish G's or Ryan Clark's answers helpful? If so, please click the "Accept" button at the bottom of the one that best answers your question. 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.

In addition, please post additional questions as a separate post on this forum, and ensure that you reply to answers with comments rather than your own answer. Please see Best practices for using this Answers site - FlexSim Community for more information. Thanks!

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Answer 1 · 2022-03-15T00:02:03Z

Ryan Clark answered Mar 15, '22 Harish G commented Mar 25, '22

Hi @Harish G,

I created an example model that demonstrates one way to accomplish the objectives you outlined in your question. I've attached an image of my model below:

The upper portion (outlined in red) uses an event-triggered source to create a new token for each item that enters the rack, then uses a Batch activity to group them by Type. The token is then pushed to a list. The bottom portion (outlined in blue) has one token to represent the processor downstream. The processor pulls one batch from the list at a time and processes the batch one item at a time (sub flow outlined in green). Then, after it has completed processing that batch, it attempts to pull the next batch from the list using a query that specifies the same type as the batch that was just processed.

If the processor is unable to pull a batch of the same type, then it just pulls any available batch.

I hope this helps! Let us know if you have further questions!

screenshot-2022-03-14-175945.png (346.2 KiB)

screenshot-2022-03-14-180058.png (36.4 KiB)

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Harish G commented · Mar 15, 2022 at 12:45 AM

Hi Ryan,

Thanks for your kind response! :-)

Can you please share the model with me, so that I can take a look at the constraints used within each process flow item for better understanding?

Thanks,

Harish

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Ryan Clark Harish G commented · Mar 15, 2022 at 06:37 PM

Hi @Harish G,

I've attached my model here. I hope this helps!

twotypes-oneproc-example-rc.fsm

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twotypes-oneproc-example-rc.fsm (57.5 KiB)

Harish G Ryan Clark commented · Mar 15, 2022 at 06:45 PM

Thanks, @Ryan Clark!

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Harish G commented · Mar 15, 2022 at 03:47 AM

Hello @Ryan Clark,

That flow didn't quite work for me as I believe I have assigned labels for the tokens right at source 1 and unsure what are the parameters as a part of your model, which might be different from what I am using. So, I am not able to navigate the objects properly from Rack to the processordownstream. I would be interested to see your model and please see my model attached.

flexsim-new - Copy.fsm

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1647315680821.png (106.2 KiB)

flexsim-new-copy.fsm (107.2 KiB)

Felix Möhlmann Harish G commented · Mar 15, 2022 at 07:41 AM

Your uploaded model looks incomplete/corrupted to me. For instance there is no list in the process flow.

Anyway, here is one way to set the logic up. I can't say if this is what Ryan built since there are of course many variations of how exactly the process flow is set up.

flexsim-new-copy_fm.fsm

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flexsim-new-copy-fm.fsm (93.1 KiB)

Harish G Felix Möhlmann commented · Mar 15, 2022 at 03:15 PM

Hi Felix,

Thanks for your model!

It works fine, but one thing it does is it just keeps alternating between one batch of type 1 and other batch of type 2 in the downstream process. Whereas, what I wanted the model to do at a point when PalletMB1 or PalletMB1 Queue is full, it needs to make a decision should it continue running the same type based on the availability to run a full batch or should switch to the next type? That way we can reduce the changeover between types, coz every time we switch from one type to another on the downstream processor, it causes changeover time of 15 minutes.

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Harish G commented · Mar 16, 2022 at 05:16 AM

@Felix Möhlmann & @Ryan Clark

Also I ran into another issue. When I was trying to increase the batch size at the queue before sink to 24, changing the rack size to hold 52 totes, it would run the 1st iteration properly, but during the 2nd iteration it gets stuck at the Wait for rack full step as you can see in the image & queue starts building up before the rack.

When I was running the same setting with batch size 12, it would work fine.

I tried attaching the new model, but it doesn't let me do it. Thank you!

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1647407799421.png (159.1 KiB)

Harish G Harish G commented · Mar 16, 2022 at 05:17 AM

Please see attached the model for the above issue regarding the batch size of 24. Thank you!

flexsim-new-copy-fm.fsm

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flexsim-new-copy-fm.fsm (98.4 KiB)

Felix Möhlmann Harish G commented · Mar 16, 2022 at 07:20 AM

I fixed some issues in the model.

1) The types kept alternating because the product type wasn't written to the token (seems I forgot to add this to the model previously). This means it wasn't available when evaluating the pull queries and the first entry was always chosen as a result.
-> Added assign labels activity to write product type to token.

2) The tokens get stuck in the wait for event because the rack is already full but not enough items for a complete batch are cured. So nothing can get pulled and the wait for event won't trigger again since the rack is already full.
-> Added a decide; when the rack is full but nothing could get pulled, the token instead waits for something to get pushed to the list.

3) To show why the processor is not working you can use a custom code activity so set it's state to something descriptive which will then show up in the gantt chart.

flexsim-new-copy-fm_2.fsm

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1647415176437.png (15.7 KiB)

flexsim-new-copy-fm-2.fsm (100.2 KiB)

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Harish G commented · Mar 16, 2022 at 06:18 AM

@Felix Möhlmann & @Ryan Clark,

Another issue: When the model runs, it simply alternates between two types without considering that there are products of same type still available in the rack and pulling them, as you can see in the picture below. I changed the batch size back to 12.

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1647411518923.png (107.9 KiB)

Answer 2 · 2022-04-04T17:24:36Z

Harish G answered Apr 4, '22 Harish G commented Apr 4, '22

Hi @Ryan Clark & @Felix Möhlmann,

I created a slot assignment in the rack spaces with certain spaces allotted for certain product. Then, I created the slot assignment strategy to be matching labels. Then when I ran the model in the first iteration it runs fine and in the second it gets stuck at the processor (Inspection) and the process flow gets stuck at waiting for rack full, even though rack spaces are available. Please help me with this and see the model attached. Thanks!

flexsim-new Model_3.28 - Copy.fsm

1649092848486.png (133.6 KiB)

flexsim-new-model-328-copy.fsm (110.6 KiB)

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Ryan Clark commented · Apr 04, 2022 at 07:05 PM

Hi @Harish G,

Please follow our best practices and post this as a new question. You can link to this question in your new post.

In addition, if you are making a comment on a question, please post that reply as a comment rather than a new answer. That helps to keep things organized.

Thanks so much!

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Harish G Ryan Clark commented · Apr 04, 2022 at 07:09 PM

Sure, Ryan. Let me post this as a new question shortly. Thanks!

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