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Make MU stay and wait in buffer

Siemens Pioneer Siemens Pioneer
Siemens Pioneer

Hi All,

 

I have a production cell with 3 testers (split into manual Load/Unload and automatic test) and 3 workers.

 

My problem is the buffer before the testers. I want the parts to stay in the buffer, until worker No. 3 comes and loads them into any free tester.

 

I managed to block/unblock single procs after buffer with the help of Method, so when part is in tester, no parts can enter; but still, an MU enters the single proc “Load” and waits in there rather than waiting in the buffer “Buffer_Before_Test” .

 

Unwanted behavior:unwanted.png

 

Worker is busy packing, but an MU already entered the Tester block and sits there waiting.

 

I would like the MU to sit in the "buffer_before_test" as I believe this would represent a true picture of buffer occupancy. How can I achieve this, please?

 

Many thanks

12 REPLIES 12

Re: Make MU stay and wait in buffer

Solution Partner Genius Solution Partner Genius
Solution Partner Genius

Hello Irina,

 

You can try locking the entrance of the Load as soon as one part enters it and unlocking it at the exit of unload.

Re: Make MU stay and wait in buffer

Siemens Pioneer Siemens Pioneer
Siemens Pioneer

 

Hi Learner,

 

thank you!

 

I am using the following method on "load" entrance front:

is
do
 If ? = Load1 then
  Load1.EntranceLocked:=True;
 Else
  Load1.EntranceLocked:=False;
 End;
end;

 

and the following method on "unload", exit rear:

is
do
 Load1.EntranceLocked:=False;
 
end;

 

Unfortunately this does not help yet. Any more ideas?

Re: Make MU stay and wait in buffer

Solution Partner Genius Solution Partner Genius
Solution Partner Genius

Hi Irina,

 

Method you are using is correct. Is exit strategy of 'Unload' is carry part away?. In that case you can try unlocking it at the entrance of station next to Unload.

Re: Make MU stay and wait in buffer

Siemens Pioneer Siemens Pioneer
Siemens Pioneer

Hi Learner,

 

thank you. The exit strategy of Unload is Cyclic, the parts go straight into buffer_before_pack.

 

I tried to make the worker carry parts away from "buffer_before_test" into the "load", still for that exit strategy I can only choose 1 MU target (successor) e.g. Load, but since I have 3 testers (Load; Load 1 and Load 11) it is not a true scenario and cannot be used in my simulation case.

Re: Make MU stay and wait in buffer

Solution Partner Genius Solution Partner Genius
Solution Partner Genius

Hello irina,

 

Try unlocking load at the entrance of 'Buffer_before_pack'. If possible, post the model or the part of it so that i can replicate the issue.

Re: Make MU stay and wait in buffer

Siemens Pioneer Siemens Pioneer
Siemens Pioneer

Model attached;

 

not sure how to let the buffer_before_pack decide, which entrance to unblock; could you help? thanks

Re: Make MU stay and wait in buffer

Solution Partner Genius Solution Partner Genius
Solution Partner Genius

Hello irina,

 

I think i got the solution. In your model, you are locking the entrance of the load station of 'Test1' but entrance to the load stations 'test' and 'test11' is still unlocked. Thats why parts are going there. You can avoid this by either 1) locking entrances of all the load stations and unlocking it at the same time, or 2) lock the exit of 'Buffer_before_Test' and unlock it in 'Buffer_before_pack'.

 

I have uploaded the model with the latter.

Re: Make MU stay and wait in buffer

Siemens Pioneer Siemens Pioneer
Siemens Pioneer

Hi Learner, thank you for an updated model.

 

We have to keep locking the entrance of the any of 3 load stations if there is a part in the tester being tested; if the tester is empty,  the entrance to the load stations needs to be unlocked.

 

The MUs are kept in the "buffer before test" and are awaiting test; Worker 3 needs to load all testers as soon as possible but until he does it, the parts needs to stay in the "buffer before test".

 

In my model, the parts leave the "buffer before test" and enter the load without worker being there (inaccurate buffer occupancy).

 

In the updated model that you sent, the parts stay in the "buffer before test" but whilst the middle tester is working, other 2 testers are under-utilised and stand empty before a part arrives in the "buffer before pack" and the entrance to load stations in unlocked (low utilisation of testers).

 

How can I achieve the behavior of keeping parts in the buffer before test until the resource (worker) comes and loads them but without loosing the utilisation of all 3 tester machines?

Re: Make MU stay and wait in buffer

Gears Esteemed Contributor Gears Esteemed Contributor
Gears Esteemed Contributor

Hi Irina,

 

why do you not use a simple exit control for the buffer? Look in the attached file.

 

Regards,

 

Steffen

 

Steffen Bangsow
freelance simulation specialist  
web: www.bangsow.eu
mail: steffen@bangsow.net