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Multiple servers with single shared capacity


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Dear Simulationists,

I am trying to model a manufacturing cell consisting of a metrology station, CNC machine, and an airblast station. Each processed batch contains 3 different parts. The batch is inspected in the metrology station, then is mounted on the CNC where the first part is machined. After the first part is machined, it is then taken out of the CNC machine and transported to the airblast station, and after that to the metrology station and the finished parts store, while the CNC machines the second part of the batch. The same is repeated for the second and third part of the batch. After all three parts are machined, the plate used as a fixture for the batch is also processed on the CNC, followed by transportation to the metrology station and the plate store. There are defect rates of different magnitude associated with different operations.

My idea was to represent each of the operation steps as separate servers (4 CNCs, 4 metrology stations, 3 airblast stations) and create a process logic that assigns a single shared processing capacity on all servers performing the same function. For example, this would not allow the second CNC to start operating if the first is already operating. I have been struggling to define this process logic for three days now, and as my desperation levels grew progressively higher, I decided to seek assistance from the experts in this forum.

I would deeply appreciate it if you share your ideas on how this process logic might look like, ideas about more efficient methods to model the scenario and any general feedback or suggestions!

Thanks,
Hristiyan

 

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Tricky problem. If you had posted this in a Simio Insiders forum instead of the public forum I could have replied with a model and figures.

I would probably take the opposite approach - instead of adding additional "fake" machines, I would consider representing each workcell as a single server that makes use of associated resources for metrology, CNC, and airblast. I'd use Task Sequences to do the sequential processing of each part, then use the associated Loopback feature of Task Sequences to start over with the subsequent parts. 

There are a number of SimBits demonstrating task sequences. Unfortunately the only one demonstrating loopback (ServerUsingTaskSequencesWithDataTables_Loopback) uses data tables (which complicates things) but you might get the idea.

Or you could do a similar approach with process logic steps.

If you repost this in Simio Insiders you might get more help.

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