If you use rolled up lead time in MRP, you need to recalculate it manually after changing your routings. The system does not update it automatically. Run the rolled up lead time action before you plan for the first time, and again whenever you change routings.
You set whether planning uses lead time or rolled up lead time on the planning template card. Rolled up lead time calculates the total lead time through the full low-level code hierarchy, so you can see how long it takes to produce a complete item structure, not just the direct lead time for a single item at a single location.
Using rolled up lead time in MRP date calculation
When you use the date functionality in the simple MRP, you can base the calculation on either lead time or rolled up lead time. You choose this on the planning template card. Rolled up lead time gives you the total lead time for building the full hierarchy of an item, instead of just the direct lead time on a specific location for a specific item.
Rolled up lead time does not calculate automatically
The important thing to remember is that rolled up lead time does not calculate itself. There is a dedicated action called rolled up lead time that you have to execute manually.
Run this action before you plan for the first time. After that, run it again whenever you change your routings. The calculation works its way up through the full low-level code hierarchy, so the total lead time stays correct across all levels of the item structure.
What you get from calculating rolled up lead time
Once you have calculated it, you can display the rolled up lead time and see the total lead time required to create the full hierarchy of an item. You can also see the direct lead time for the specific item on its specific location. This gives you a realistic picture of how long production actually takes when an item depends on several underlying items.
Q&A
Does rolled up lead time calculate automatically in MRP?
No. Rolled up lead time does not calculate itself. You have to run the rolled up lead time action manually.
When should you recalculate rolled up lead time?
Run the rolled up lead time action before you plan for the first time, and again every time you change your routings.
Where do you choose between lead time and rolled up lead time?
You set this on the planning template card, where you can select either lead time or rolled up lead time for the date calculation.
What is the difference between lead time and rolled up lead time?
Lead time is the direct lead time for a specific item on a specific location. Rolled up lead time is the total lead time needed to create the full hierarchy of an item, calculated through the entire low-level code structure.