Overlap functionality in shop order scheduling

Question

In shop order operations, it seems that the Overlap functionality does not work correctly.

While CBS and APB are not used, and Infinite scheduling is used, see the below example,

Calendar configuration has 5 working days (Mon-Fri) 8 AM to 12 PM and 1PM to 5 PM (8 hour day).

Work center utilization - 100 %, all operations efficiency - 100%, Resource capacity of the WC - 100

Operation 10 has 24 Machine Run Time (unit - Hours) and no set up time

Operation 15 has 12 Machine Run Time (unit - Hours) and no set up time and have a Overlap of 50 percent

Same work center for both operation.

As I understand, the start date/time of the second operation should be 12 hours (50% of 24 hours) after starting of the first operation, which should be 1/25/2021 1.00 PM. But it is scheduled as 1/26/2021 10.00 AM (18 hours after).

Is system check something other ? Or system calculate in a different manner ?

Thank you in Advance.

Thushitha

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Best answer by Björn Hultgren 21 January 2021, 20:28

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Björn Hultgren · Accepted Answer

I think it schedules correct. If you set 50% overlap it indeed means you can start 15 after 12 h working on op 10. However, if system would schedule op 15 from that time it would finish at the same time as op 10. Think about it, that would be practically impossible since the wip from op 10 need to arrive in time for processing on op 15. So in this case the limiting factor will be that op 10 can't finish until op 15 has been processed up to 50%. That means 6h before op 15 is finished.

Hi @Björn Hultgren ,

Thank you very much for this explanation. From this, I was able to do some more testing, and able to find how it works. seems the logic checks for the further date out the results from above two conditions.

Thank you again !

Thushitha

Thushitha Chandrasiri · Answer

I think it schedules correct. If you set 50% overlap it indeed means you can start 15 after 12 h working on op 10. However, if system would schedule op 15 from that time it would finish at the same time as op 10. Think about it, that would be practically impossible since the wip from op 10 need to arrive in time for processing on op 15. So in this case the limiting factor will be that op 10 can't finish until op 15 has been processed up to 50%. That means 6h before op 15 is finished.

Hi @Björn Hultgren ,

Thank you very much for this explanation. From this, I was able to do some more testing, and able to find how it works. seems the logic checks for the further date out the results from above two conditions.

Thank you again !

Thushitha

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