MRP Build Need dates


To setup MRP I have put lead times into the warehouse for all of the subcomponents of a given top level BOM item. However, I am not using the advanced production scheduling feature, only the MRP build module to a start work order to fulfill need, so my labor plans and build estimates within them are not up to date (some are but not all).

Are the warehouse lead time estimates used to generate MRP build suggested build/buy dates (even for “build” items?) or does/can the MRP pull from the build estimates in a labor plan?


Hi, Paul,

Thanks for reaching out. Good question. MRP pulls the lead time from the warehouse lead time estimates.

Cetec ERP Support

OK, so if I have a need to build QTY 100 items that have a lead time of 1 day in the warehouse leadtime field, the MRP will assume I can get all 100 items in 1 day and put a need date 1 day prior to the need, is that correct? Even though we have a labor plan and production location capacity that says we can only build QTY 5 per day, requiring a work start date lead time of 20 days. I just want to make sure I am correctly interpreting the CETEC MRP logic.



To clarify, when I’m saying that MRP pulls “warehouse lead time estimates” I’m saying that, for this column on MRP


Cetec is looking at the lead time that was set in the warehouse section of the part record. So, if I were to go to the part record for my BOM and then scroll down to the warehouse section for the warehouse my order is being placed in, I’d see the lead time that’s been manually set for that warehouse:
image That number is what the MRP report will show in its lead time column.

The warehouse lead time indicates the time it will take material to get from a vendor to your shipping dock. So, this is separate from the time it will take your team to complete an order. Rather, it’s just one piece of how MRP calculates when you will need to buy or build parts.

In your example, I wasn’t sure if you were saying that you needed to buy these parts or build them. But let’s say you’re talking about a build order in which you need to build 100, and you have the capacity to build 5 per day. These numbers would factor into the work start date on the quote. Quotes are affected by the labor plan for the part that is being quoted. Once that quote is committed to order, MRP will use the work start date as part of its calculations to determine what parts need to be purchased and when.

So, to answer succinctly, the warehouse lead time is concerned with vendor time frames, not the time frame for your company to complete a work order.

Does that make sense?

Yes, this is more inline with what I was expecting.

So the BOM (build) items that show up in MRP build list do not have a recommended buy date (or recommended work start date), instead they show a need date for the unfulfilled demand that is missing material to complete the order. In other words, it doesn’t take into account the work start date on a given order, just the missing items.

So it is up to purchasing/production to order the missing material and schedule the needed build orders to satisfy the work start date listed, do I have that right?


Well, actually, MRP does take into account the work start date–it’s taking into account not only what items are missing, but also when those items are needed.

In answer to your question, though, yes, purchasing/production has to order the missing material and schedule the needed build orders based on what they see on MRP. You can think of MRP as a very informed guide to help you know what purchases and orders are needed, rather than a “doer” that will set up purchases or orders for you.

If it would be helpful, here’s some training on MRP that might help with the logic behind it and best practices for using it:

Let us know if you need further help,
Cetec ERP Support

Thank you! That actually clears up a lot. I appreciate it!

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