Combiner / getting all parts in a batch

You can see in model i have to combiner and some sources. The target is that the operator should transport all pieces to one combiner before starting the transport of the pieces to the other one.
So if he gets info to transport main part to combiner he should transport also all other parts from components list.
In the samnple he starts with 1st combiner and first part and then changes to 2nd combiner. But he should wait until he gets info the transport next part to 1st combiner.

The operator does it´s tasks as they are created. Tasks are created as soon as an item can be transported. This means after they arrived, outputport and inputport has to be free. All created tasks are stored in order of there creation in operator (or dispatcher if you use one) and started as soon as a operator is free.

So what you can do is, change the order of creating tasks by change the order of arriving items.
Or close and open ports in order you want items been transported.
Or you create your own tasksequences.

Marco,


in this case it is a little bit different. This task can't be solved by breaking into task sequences like "Same Destination", just because the combiner doesn't open his inports 2 and 3 before item 1 arrives. So there is no way to combine these transports with FlexSim standard pick options...unless you use a little trick:


I added another Source to feed a dummy item into port one of the combiner with no transport not to mess up operator statistics. Once the item hits the combiner, inputs 2, 3 and 4 open at the same time and you can combine the transports into one travel. This is what I changed to your model:
- Added dummy source
- Set up operator capacity and break to requirement
- Deleted entry trigger on combiner. There is no need to call "transportincomplete()" manually, since the model uses FlexSim standard task sequences.


Nevertheless it might be worth wile to explain exactly what you want to accomplish. The model is of course still sensitive to flowitem availability: If not all items are available in the three upstream queues at the point of time the transport is generated, that will result into multiple transports again.


Let me know if you need further help on this.


Best wishes


Ralf
FlexSim

This is one way but not the perfect one because operator cannot take more then one part in reality. If i change capacity to "1" in simulation the operator mix the transport again.

I think i will change my model in that way that i will avoid to create other task until the operator finish all of the transports to combiner. This is not nice but something i can (maybe) realize.

Hello Marco,

you can build a filter consisting of several Dispatchers. All Tasksequences are sent to one Dispatcher. In its Pass To function you querry for the destination of the tasksequences getaskinvolved(tasksequence,4,1).
Then you distribute the tasksequences with the same destination to the next dispatcher. He collects all tasksequences in the order of appearance.
The taskexecuter himself is connected to all the dispatcher of the second stage. He closes and opens the output of the second stage dispatchers as long as he wants to work for one combiner.
But the combiner itself is not easy to fit with products, because the combined items from input port 2 and higher will be collected only after the palette-item from port one is received. There is everytime a time gap between the tasksequences for the products the combiner collects. That is what RalfGruber says.
Another approach could be:
If you want to set a taskexecuter to one combiner for a single combination process, you should give received tasksequences for this combiner a high priority and you should give the Taskexecuter a utilizetask after delivering of the first item (the palette item). You can free the taskexecuter firstly, when he receives the next tasksequence for this combiner.
To transport all Items at once to the combiner the taskexecuter can use his break to function for same loadstation. But this works only for the second, third, forth... items to combine.

Jörg

Thank you Jörg but I am really new with Flexsim! Sounds for me difficult and without a sample I don´t understand what you mean. Sorry

But i solve it in that way -> look to the sample.

Hi Marco,


I obviously misunderstood your first post, thinking you wanted the operator to take all items on one trip. Then there is not necessarily a need for the dummy item anymore...


Your solution is good, but has one weakness: When one source feeds both of the combiners, the two combiners open and closing the source's output will interfere with each other.


There are multiple other ways to get around that, but before making a suggestion here's the all deciding question:
Can we assume, that the items called from the combiners all ALWAYS available at the upstream objects?


Maybe you want to elaborate in a little bit more detail about the technical constraints on the process?


Thanks and best wishes


Ralf
FlexSim

Hi Ralf,

not so easy to answer! In 70% on the cases they are all available. Just think about the situation you transport the main part from previous station to next station (which is combiner) and the operator now takes the rest of material out of some boxes close the the station. I would define that there is always material in box.

In 30% of the cases it is not sure. This can happen when we will merge to main parts from to streams. Because of different cycle times in both streams there can be main part from first stream but no part from second stream.
In that case operator will put main part in combiner and then stop working until he gets rest of material. This is realistic because he will not check the avaiability of all parts before starting assembly.

Is is clear?

Hi Marco,


as long as there are dedicated sources for each combiner (meaning that no source feeds two different combiners) your approach should work just fine.


Once you find that you have a source which provides parts for more than one combiner, we need to continue this discussion, possibly with you providing a model for a specific case as a starting point.


Best wishes


Ralf
FlexSim