Firming types in MRP

In a production environment it may not be preferable that new requirements on the short term can influence production quantities. The length of the term can be determined by the planning time fence. How MRP treats new requirements in this period can be determined using the firming type in customizing for MRP type:

The firming type determines how the MRP run treats requirements in relation to the planning time fence. The time fence is counted by number of workdays from today. This number can be set in the material master (MRP1 tab) or in customizing per MRP group.

Firming types

Firming types

There are five firming types:

0 – Time fence has no effect on planning: new requirements are always accepted and increase/decrease any non-firmed orders (planned orders, requisitions).

1 – All non-firmed planning proposals moving into the time fence will automatically be firmed by the system. This way no automatic changes will be made to these order in future planning runs. When new requirements within the time fence are identified by MRP, these will result in new non-firmed orders lying just outside the time fence.

2 – All non-firmed planning proposals moving into the time fence will automatically be firmed by the system. Again, as in 1, no automatic changes in the time fence are made. Contrary to 1 NO new proposals are created at all. It is up to the planner to identify the shortage and deal with it.

3 – No automatic firming of any non-firmed planned orders, either within or outside the time fence. All orders are moved outside the time fence and remain non-firmed.

4 – No automatic creation and/or firming of planned orders to cover shortage


One thought on “Firming types in MRP

  1. Pam Oakes

    We have been using the planning time fence. We also use GRPT. In all the questions/answers on the web, I can’t find the data on how it really works relative to GRPT. Based on how we are using it the planning time fence input into the system when you are using firming type 1 should be equal to the GRPT plus the fixed time period that you do not want orders to change.
    I believe that if you run MRP once a week, and you input a planning time fence of 8 (with 3 days of GRPT) you will only get fixed schedules for 5 days. If you want fixed schedules for 10 days you need to have a planning time fence of 13 days. Can you confirm this is the case?


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