We have a problem with Shop Order requisition due dates relative to shop order start dates that result from a MRP run. If our order quantity is 1, the manufacturing lead-time is 5, and the due date is 09/25/2020 then the start date will be 09/24/2020; why is it not offset 5 days? Should be offset by the fixed manufacturing lead-time. If we change the order quantity to 10, then the start date is offset by 10 days and is 9/15/2020; this is not good. We want to use “standard practice” where the lead-time offset is not affected by the order quantity size.
Can anyone please help with this?
Best answer by majose
I just double checked the server code in Apps10 right now, and I know it is the same logic in Apps9.
In the heart of the MRP, when the engine is creating shop order requisitions, (yes it happens in “main MRP step” these days) system gets hold of the Routing for the part, and it uses the information that you have in Routing screen. Using the lead time information in the tab Routings, in the mid-portion of the screen. To be more precise, MRP logic uses the Fixed By Day and the Variable by Day fields. The Variable by Day is multiplied with the Shop Order Req Qty. The start date of the Shop Order Req is basically calculated like this: Required Date - (Fixed Lead Time per Day + Variable Lead Time per Day * Shop Order Req Qty). Please note that we are talking manufacturing calendar days here, so I simplified the equation a bit, to make it more readable.
Only if the expression (Fixed Lead Time per Day + Variable Lead Time per Day * Shop Order Req Qty) is 0, THEN it goes for the manufacturing lead time on the Inventory Part screen.
Then you can always customize this, but it is a bit scary.