SO Dates and MRP - Planning Guru Help Needed


I am just starting to familiarize myself with how my company has Epicor set-up (I started working here in April with previous SAP experience).

I read this on another thread:

The system will not plan until the need date is within the ‘fence’ of the Lead-Time of the part;
so if: [Forcaste Date] - [Lead time] is > today, MRP will not plan the order since you do not have to start it yet.

With this knowledge, MRP is not creating jobs for orders outside of 5 weeks (our finished product’s lead time) and so the production supervisor is creating jobs manually in Epicor for orders out 6 months so that PO suggestions will populate. Some material lead times are 8-12 months so I am assuming they are carrying up to 6 months of stock for the longest lead time items.

This is wrong and I would like some guidance as to what fields should be changed in order to have MRP prepare suggestions (job and purchasing) out 6 months. How do I change the planning fence? My hope would be that the suggestions update every time MRP runs and the production supervisor only firms a suggested job when it falls into the 5 week production lead time.

Background: Management is trying to track “revenue attainment” in an excel spreadsheet. They export open orders and then review with the VP of manufacturing as to “when” he thinks the orders will actually ship. Then they MANUALLY update the excel sheet by moving the order value into the month they believe they will be able to invoice the order (when it ships). If MRP is working, should it not be suggesting a promise date based on current demands, lead time, materials, etc? Is it shown in the SO?

Thanks in advanced!

when you run MRP, what are the settings?
are you running it with a cut off date?


I am definitely no expert. But I think you want to use the Dynamic Days of Supply functionality to make sure MRP factors in long lead time purchased parts.

Your finished product lead time is not 5 weeks if the material lead time is 8-12 months. You need to open up that lead time so that MRP will create the job that will create the PO suggestion.

I had that kind of situation where we bought a machine complete part using a subcontract op. Then made sure the lead time covered the lead time for that part so that the subcontract PO for the machined part could be ordered in time.


We don’t use MRP and our company is horribly bad at managing a schedule…

That being said, a couple of the things you mentioned are a little contradictory. If you are looking to get demand into the system based on orders, then you need a due date first to make that work (backward scheduled). If you are looking to get promise dates based on lead time and material, then you are forward scheduled and the required materials should be ordered on a regular schedule with orders getting dates based on resources (materials and labor). Generally, only the long lead time items or the ones that dictate the pace of manufacturing are your constrained materials and everything else fills in from there.

It’s a chicken and egg problem and not an easy one to solve, but someone needs to decide which way the scheduling is going to work (forward or backward), because trying to use both is circular reasoning.

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I can definitely help you with this, but it’s a complex topic.

The post about establishing a proper cutoff date is accurate. Make sure that you are using a cutoff date that is beyond the demand date of the items you want to plan.

There is no “fence” per se, the cutoff date when you launch MRP determines how far out you want to plan to available demand. If your cutoff date is 12/31/2019, you won’t get any plans for demand that is 1/1/2020 or later. In effect, you set the fence each time you run MRP.

Lastly, if the lead time to make a product is 8 weeks, and the lead time of the raw material for that item is 6 months, the lead time of the material item should be set to 6 months, and the lead time for the fabricated part number should be 8 weeks. Don’t build your procurement lead times into the lead time of the part - it won’t do anything for you. The jobs are going to schedule via the scheduler regardless of the lead time value of the make item.

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As others have mentioned, there is a cutoff date when you run MRP, but there is also a “Planning Time Fence” that you can set at the part/Site level AND/OR at the PartClass / SITE level (Part/Site “wins” over the partclass setting). If the partclass for the part and the part/site are both set to zero, then there is no timefence considered, so it will plan forever into the future (unless you specify a cut off date which will ALWAYS win).
Typically, I see most companies set teh planning time fence for all their parts and partclasses to zero, and they don’t use a cutoff date. BUT, that is different in some industries where they have shorter leadtimes, and/or just want to eliminate future details.

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We do backdate the “Schedule start date” field approx 3 months to ensure we haven’t missed anything. here is how it’s set to run:

Update: I have been told that our MRP is working well now (we have the correct lead times for all procured parts). The issue we are having with jobs not being suggested is because they do not have the MPS turned on in Epicor.

Looks like I need to do more research on how we have the system currently configured.

Update: We are not using the MPS in Epicor which is why they are creating the jobs manually. MRP is working, PO suggestions are being generated.