when MRP runs I noted that in different SAP systems sometimes are created PRs, sometimes planned orders and sometimes production orders.
Why there is not the same approach ? What is the difference between the above configurations? And how customize the SAP systems to define that when MRP run will be created a PR or a planned order or a production order ?
1. MRP creates procurement proposals such as PldOrd, PurReq, etc but never creates production orders (PrdOrd), purchase order (PO), etc.
2. In the material master, MRP view 2 you can maintain 'F; 'X', 'E' procurment types (and there are special procurement types e.g. for subcontracting, plant-to-plant transfers, etc). This (or these, considering the special procurement as well) is one factor MRP considers.
3. When you execute the planning run (MD01 / MD02 / MD03), you can influence trough 'Creation indicator' wether MRP should create PldOrd or PurReq for external procurment. Please check:
4. It is important to know the source determination process as well:
(e.g. in case of procurement type 'X' system should decide which source to use...source list, QA, etc play role in it...)