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Sequence dependent setup activity question

swathi_rege
Active Participant
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682

To do sequence dependent setup activity, I need to create setup group/key and matrix. once I do that, I can use schedule sequence heuristic and sort my orders based on setup. so I can use normal heurictics to consider setup times from the matrix and perform setup dependent scheduling..

But I have read some comments in the forum that we need to use PPDS optimization to consider setup times and optimize the schedule..

My question is,

what functionality do I get when I use schedule sequence button (and sort by setup) in rescheduling function Versus PPDS optimizer?

Accepted Solutions (1)

Accepted Solutions (1)

Sasi2005
Contributor
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Hi Swathi,

As long as you have assigned setup matrix in the relevant resource (on pp/ds side), it shall pick up the transition values from the setup matrix.

Hope it helps.

Regards

Sasi

Answers (2)

Answers (2)

Sasi2005
Contributor
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Hi Swathi,

Yes, if you use the setup group as a sorting parameter in the strategy profile and you run the Reschedule heuristic, then you will get with the sequence G1,G2,G3,G4. Please note you are having only one order per group here, which is generally not the case ,in practice. The advantage of this method is all orders involving G1 you would like to run in a single run say you have 5 orders of G1 group, 2 Orders of G2 group, 1 order of G3 and 2 orders of G4 and the setup time change over between G1 and G2 or G2 and G3 is very large and similarly others then it makes sense to run all orders related to G1 first thus you need not to have a setup activity between consecutive orders of G1 and similarly other groups . So it depends on the business scenario what you want to achieve.setup-group.png setup-group-result.png

In case of optimizer it takes the weightage of parameters that you are configuring , in some industries it could be setup time in some industries it could be delays (delay has higher importance than setup). Thus producing a result which takes all the constraints not just setup before producing a result. setup-opti.png.

I have attached some screen shots for your ready reference, the reschedule using setup group (setupgoru-result.png) and the optimiser in the file (setup-opti.png). Hope this helps.

Regards

Sasi

swathi_rege
Active Participant
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Thanks a ton.. One last question before closing the thread

so in reschedule heuristic, if I sort using setup group, then below things will happen

1. Sequences all orders based on setup group (for example - G1, G1,G1, G2, G2, G3, G3, G4, G4, G4) - Clear from your screenshot

2. The setup time between G1 and G2 - It be read from setup matrix but not from routing (please confirm)

If I use optimizer, then setup sequence will be like below (G1, G1,G1, G4, G4, G4, G3, G3, G2, G2 - optimized based on time)

Sasi2005
Contributor
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Hi Swathi,

The answer to your question lies in your question itself. When you do a reschedule function or a schedule sequence you are aware how the sequence should be, i.e. Its a predefined sequence. In that sequence some of the setup times may be less or more but its a predefined regular sequence (like a sort sequence). Say for example you have a product which can be produced on two modes, the schedule sequence doesn't consider both the modes during execution, as it goes resource by resource. It's also not an optimal sequence. All these challenges are overcome by using PPDS optimizer, which is based on the weights (cost model) assigned appropriately against setup, delay , make span as well as mode costs. Its a kind of helicopter approach. Through this kind of overall approach it provides you with an optimized schedule.

I hope its clear.

Regards

Sasi

swathi_rege
Active Participant
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Hi Bhushan,

Thanks for the comments.. but I am still not clear.. Let me give you an example. Please see attached screenshot and that is our setup matrix. we are not using optimizer but we would like our orders to be scheduled based on optimal setup time (we have only one mode and dont care about cost)

Questions

1. Planned order (P1) has setup group G1, P2 has setup group G2, P3 has G3 and P4 has G4. Are you saying that if I use schedule sequence button in rescheduling function and sort by setup group (ascending), then system would not care about setup matrix time/table and will just schedule P1,P2,P3,P4 in this sequence (and use routing setup times) because setup group sorting happened in G1,G2,G3,G4 fashion? or the sequence is still P1,P2,P3,P4 based on setup group sort, but instead uses setup matrix times like below screenshot?

2. Only if I run optimizer, then system will come up with optimized schedule sequence with minimum setup time like above?

Thanks

Swathi