Operator Task Priority: Feed Before Collect in FlexSim

[begum_aydemirM7H9M]

In my model, I have two operators connected to a dispatcher. These operators pick boxes from the source and deliver them to the input of the combiners. Once the process in a combiner is finished, the operators pick up the finished product and place it onto a conveyor. Since there are multiple Combiners in the model, the operators currently prioritize collecting finished products from the combiners over feeding empty ones. However, what I want is for the operators to first supply boxes to any empty combiners, and only then collect the finished products from those that have completed processing. How can I implement this task prioritization in FlexSim?

Thank you in advance for your help!

[moehlmann_fe]

Just increase the priority on the sources so its higher than that on the combiners. Depending on how the source is set up, it might only have a single item available to be picked up at a time (inter-arrival source). In that case, consider inserting a queue between the source and combiners so you can have multiple pending transports at once.

[begum_aydemirM7H9M]

In a small test model, the operators first pick up boxes from the source and place them into the combiners as expected. However, in the full-scale model, the operators prioritize emptying the combiners sequentially rather than feeding the empty combiners first. The source actually has products ready and queued, with multiple items available at time zero. How can I effectively implement task prioritization in this scenario? Could you provide more detailed guidance on setting up the priorities?

[moehlmann_fe · Accepted solution]

Here's an example model that I built. The operators prioritize transport tasks from the source to the combiner.

If multiple combiners finish shortly after one another, they will first be emptied, because no transport tasks from the source might have been generated yet. A combiner can only receive a new container item once it is empty and it can only receive items through other ports once the container item is present.

If you need more detailed logic you can always use some dummy object like a queue and handle the creation of transport tasks in Process Flow.

[begum_aydemirM7H9M]

Unfortunately, in the example simulation you shared, even when there are no pallets remaining in the combiner, the system prioritizes unloading the combiner rather than sourcing pallets and boxes. How can I set prioritization in the process flow? Is there an example available that demonstrates this?

[moehlmann_fe]

Can you name a model time where this happens in the model I shared. As I said, they don't "prioritize", they start the highest priority task available at the time. The fact that another task with a higher priority becomes available afterwards doesn't matter by default. You can allow the tasks from the source to preempt other tasks, but then you will at some point end up with transporters driving to the source will already having a full pallet loaded.

Attached is an example of how Process Flow logic could be used. Replenishment tasks are created as soon as the previous step (removal of previous pallet, getting pallet) has been started rather than finished.

Note though: The overall throughput is actually slightly better if the priorities are reversed because there is fewer risk of operators needing to wait for each other.