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How to overlap between shop oders during MRP Infinite Scheduling

  • 19 January 2023
  • 3 replies
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Elthuad Brongak
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Hello,

 

We have a case;

Think of a prod structure : 

  • Part No : A (Main Part) (Got 1 operation )
  • Part No: B (Component Part of A) (Got 1 operation ) (Qty per assembly=1)
  • Part No: C (Component Part of B) (Got 1 operation ) (Qty per assembly=1)

 

we have no stock or supply for part  A ,B , C

and we have shop orders like 

 

for required lot size of 1000 parts B and C have ( 10 days operation lead time)

 

  • Shop Order (1234) : Part No A , Lot Size 1000  (Shop Order Operation Lead Time of 10 days) Need Date 25.03.2023 

Think of a calendar of 24 hours working and no holidays.

Mrp creates  shop order requsitions  for shop order 1234 like ,

 

Requisition no (123456) : Part B need date: 15.03.2023 and required to start date : 05.03.2023

Requisition no (123457) : Part C need date: 05.03.2023 and required to start date : 24.02.2023

 

I want to make MRP to create shop order requisitions like having the behaviour overlapping function between each others.

 

Part A can start after part B has produced 500 units 

Part B can start after part C has produced 200 Units 

 

it is something like balancing the shop orders between each others. It is like scheduling   , but not with operation overlapping , overlapping between shop orders.

 

Requisition no (123456) : Part B need date: 17.03.2023 and required to start date : 13.03.2023

Requisition no (123457) : Part C need date: 13.03.2023 and required to start date : 10.03.2023

 

Is there anyway to do this on shop order requisitions?

Thank You,

 

 

 

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Best answer by matt.watters 9 February 2023, 21:18

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3 replies

Manxmano
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Userlevel 2
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As your lowest lot size is 200, I would set this as the max lot size on all inventory parts.

MRP should then chunk up the supplies to meet the total demand of 1000.

As the work can effectively be done in parallel, experiment with the order gap time (inventory part/manufacturing tab) to create overlapping shop order reqs for all parts.

matt.watters
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Userlevel 6
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@Elthuad Brongak Something to consider is the use of Lead Time Offset in the Product Structures.

Lead Time Offset

  • The number of days before the end date of the order that the component part is required. If this value is 0 (zero), the component is required at the beginning of the order. If the lead time offset is greater than the time between start and end date, start date will be the component required date. The Lead Time Offset will not be considered if the material line is connected to an operation. Instead, the start date of the operation will be considered as the date on which the material is required.

The picture below represents the scenario you defined above. Setting the LTO for B in the structure for A to 5 days and the LTO for C in the structure for B to 2 days should get you the result you want.

Experiment with this for the scenario above.

 

Regards - Matt
Elthuad Brongak
Rank
Userlevel 1
Badge +2

@Elthuad Brongak Something to consider is the use of Lead Time Offset in the Product Structures.

Lead Time Offset

  • The number of days before the end date of the order that the component part is required. If this value is 0 (zero), the component is required at the beginning of the order. If the lead time offset is greater than the time between start and end date, start date will be the component required date. The Lead Time Offset will not be considered if the material line is connected to an operation. Instead, the start date of the operation will be considered as the date on which the material is required.

The picture below represents the scenario you defined above. Setting the LTO for B in the structure for A to 5 days and the LTO for C in the structure for B to 2 days should get you the result you want.

Experiment with this for the scenario above.

 

Thank you Matt. That is the answer i have been looking for.

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