Help needed for student project (base stock model)

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Ludovic S asked Aug 6, '18 tannerp commented Aug 13, '18

Help needed for student project (base stock model)

Hi everyone,

For a student project I need to analyse a certain inventory system, but unfortunately I have not been able to implement it in Flexsim. The basic idea is that a product (demand = 300 units per period) is ordered in batches of size 1266 units once its inventory level goes below 1280 units. Upon release, the lots goe immediately into setup (0,5 periods) and production (400 units per period) if the process is idle. If the process is busy, jobs wait in queue under the first-come first served discipline. To me it seemed a very easy undertaking, but after a few days of trying and an approaching deadline I am feeling kind of desparate now.

The general structure and the model are attached below. I really hope someone is willing to help me out as this is my last resort. If implementing this model takes a lot of time, I am more than willing to compensate for it.

If more information is needed, I'd be more than happy to provide it.

Thank you for taking the time to read my question

Kind regards

Ludovic

Software Version:

FlexSim 18.1.2

base stock student project

flexsiim-base-stock.png (214.6 KiB)

basestock-flexsim.fsm (19.8 KiB)

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Answer 1 · 2018-08-06T08:06:32Z

Joerg Vogel answered Aug 6, '18 Joerg Vogel commented Aug 6, '18

The sink pulls at a rate of 300 items per period constantly or all at once. You create a constantly demand with a processor at the exit of the Inventory (rack). A demand all at once can you get with a queue. You close the output of the queue at the OnReset trigger. You batch 300 items. You close the input of the queue and you open the output in the trigger On End Collecting. On Exit trigger you close the output if the content of the queue is one and you send a delayed message to this queue. In the OnMessage trigger you open the input. The delay last your consumption period.

current.subnodes.length == 1

The Machine process one root item in a period. This root item is used to get 400 items in a Separator object. The process time is set to 0 in the separator. The separator splits the items By Expression (picklist option Split/Unpack Quantity) to 300. The separator transfers the produced items into a queue. The batch size is set to 1266.

The additional setup is different. If the setup occurs always, you set the time in the Machine processing the root item. If the setup occurs after the machine is in idle state, you set the setup time by the template "Values By Case". The Case Function is controlled by a label of the Machine. Therefore you add a label at the machine, then set a name and a value. In the setup template you use this label

current.yourGivenLabelname

to control the setup time. The time value is your setup time.

The Case default gets the value 0.

You get the data to replenish the inventory On Exit trigger of the rack. If the rack content is 1281 you open the input of the Machine and set the setup label value matching to the case that causes the processor to use the setup time. In the OnEntry trigger of the Machine you set the setup label to a different value, that the next processed item not getting a setup.

You close the input of the Machine if the content is reached in the Inventory.

If you need a content in the rack at start you place an additional source. The source Arrival Style is set to Schedule and you set a start Quantity in the first row of the table at the bottom.

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Ludovic S commented · Aug 06, 2018 at 05:28 PM

Can I ask you what exactly a root item is and how do I implement its creation?

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Joerg Vogel Ludovic S commented · Aug 06, 2018 at 11:47 PM

I called it a root item, but it is just a simple item, like any other items. I use this name because it is just one item at the processor(Machine). I set up and process this item, and then I use this item to get multiple items in a separator. I think it make the model control a bit complicated to set up and process 300 items.

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