Andrea F avatar image
Andrea F asked Andrea F commented


Hi everyone,

I am having difficulties find the solution to this modelling problem. The problem is the following:

I have products with different lenghts and i want to pack them on pallets in order to stack them in time 0 in racks. I have some data:

- number of items for the initial stock in excel table with the respective Length

- Maximum number of items i can stock in a pallet depending on its length

I also have this constraints:

- the pallet can stock only the items with the same length (one pallet has to stock homogeneous length)

- Depending on their length the maximum quantity of items is fixed

My Solution

I created a process flow with two separate sources: one for the FlowItems and one for the pallets. In the FlowItems source i imported an excel table with the deterministic quantities of products and the associated labels such as: Length, ArticleCode, Itemtype and itemsPerPallet. Instead in the Pallets Source i created an arrival schedule with fixed amount of pallets (calculated in excel in order to stack each product).

After doing this i created a process flow for palletization in order to retrieve the first item from the FlowItem list then after this retrieve the rest of the items (ExtraItems) according to the quantity: ItemsPerPallet -1 where ItemType = token.FirstItem.ItemType. Then put those items on a pallet.

Something does not work and it is throwing me errors in the system console.

Can somebody help me to solve this problem?

Sarner Holz Final Palletization.fsm

FlexSim 19.1.2
flexsim 19.1.2logisticspalletsloadingpacking
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1 Answer

Eric M avatar image
Eric M answered Andrea F commented

Hi @Andrea F, it looks like there were a couple things leading to the errors. In the second pull from list activity, the required number should be token.FirstFlowItem.ItemsPerPallet. Because that middle part was missing, it didn't know what to reference. I also changed the "require number" to 0. It will look at the list and try to pull the request number, but if there are less it will only pull the items still on the list. This is needed for the order with only 1 item and those pallets that don't get filled completely.

It looks like the Query was also causing some issues. One reason for this is because only the item was getting pushed to the list. It doesn't automatically push labels or anything else to a list (can be seen by clicking "view entries" on the list). I created a global list instead and added ItemType and ArticleCode to the list which makes it possible to Query by those categories.

In the pull from list activity I changed the Puller to be the token.FirstFlowItem. Then you can query using WHERE ArticleCode = Puller.ArticleCode.

There were a couple other changes I made that were mostly for making it easier to check the model using the step command. Instead of creating a token for each flowitem / pallet, I just created one token and then in the create objects activity had it create the desired number of objects. Lastly, I also updated the flowitems to change size based on the "length" token value which I assume is something you'll want to do in the future. sarner-holz-final-palletization-em.fsm

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Andrea F avatar image Andrea F commented ·
Thank you very much for the precious help it was what i wanted from the model. yes i also wanted to change the visual that fixed the problem
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