Scheduling, Override Material Constraints


I have scheduled a job (Job Number 036131-1-1) and I backward scheduled it and it is due 7/10/2023. I have not checked override material constraints and no check on finite schedule.

It results in the job being scheduled as shown. It puts 20 days between the stencil operations on Asm 28, operations 30 and 40.

I am trying to figure out why the big gap between the operations. If I reschedule the job and check mark the override material constraints then the job finishes on July 6 and there are no gaps between the stencil operations.

This implies that there is a material constraint that is pushing out the second stencil operation. The second stencil operation needs two materials, the stencil (PN# 151078) and ink (PN# 146294). The stencil is set up as a non stock and not quantity bearing part. We also put the lead time as 0 days.

For the ink, the set up is the same way as the stencil.

I was able to retrieve the Scheduling Debug Log file. I am attaching the file. Here is what it has to say about the Asm 28, operation 40.

Please help me understand the material lead time. Why is it bumping it out to 7/22/2023 when I have lead time set to 0?

Thank you for the suggestions and insight,

What do you have for open POs for 151078?

There is no open PO for the stencil (PN# 151078). We already have the stencil on-hand. But since we have the part as not quantity bearing the inventory is showing zero.

The stencil is considered tooling and goes into an expense account. They didn’t want to inventory the stencils so they became marked not quantity bearing. We also don’t backflush the stencils. They are sitting at a 0 quantity all the time. And we have turned off generate PO suggestions.

Thank you for thinking about my issue,

Material Constraint means that the scheduling engine will not schedule the operation to start until all material is available (or projected to be available). Something is causing the system to think that the stencil is not available until the 23rd. Do you have a lead time on the Part Class?

Hello John,
I agree with everything you said especially “something is causing the system to think that the stencil is not available until the 23rd”.
The stencil is in a part class called Tooling/Fixtures/Stencils and the part class has 0 for default part lead time.
The system thinks we have no stencil available because we have 0 in stock (due to no quantity bearing). The system thinks we have to order it. But we have 0 day lead time. I thought the system wouldn’t bump it out days since the lead time is 0.
The stencil is considered non-stock. I was wondering if this somehow affects it. We also do not have a PO or even PO suggestions for the stencil. And I was wondering if this somehow affects the scheduling.

Are you able to recreate this in a test environment where it can be an unfirm job? The “MRP and Scheduling” logs typically point you in the right direction but once a job is firm I don’t believe you can see the scheduling log.
The other thing to look for is the scheduling options. We’ve seen this issue where several of the operations are Start-to-Start but we have a Finish-to-Start in the middle of them. This is how manufacturing “needed” the jobs setup, so I’m not going to get into why we wouldn’t just change our operations to group all the start-to-start together :roll_eyes:

Couple of other things to check. Is the material marked Buy Direct on the Job? Is there a supplier price list for the part?

Hi John,
Most (about 97%) of our purchased parts are buy to stock. But stencils are set as non-stock. You gave a good suggestion to check if the part is “Purchase Direct”. I have never investigated that area of Epicor. Yes, both materials in question are “Purchase Direct”.

We do not use Supplier Price List. I looked up the supplier on Supplier Price List. There is an entry for MISC but it has 0 for lead.

These two areas are all new to me, can you explain how this impacts scheduling?
Thank you,

Purchase Direct indicates if this material is to be purchased for the Job. I would try unchecking it and see what results you get.

You also use the term “non-stock” in a sense that implies “not quantity bearing”… and these are two distinct terms with completely dissimilar meanings.

On the main Part Entry window, there are two checkboxes, one for each (they also appear at the Part > Site window, as they can be different in different sites).

The Quantity Bearing checkbox (selected by default) means that Epicor is keeping track of inventory quantity. Uncheck the checkbox and Epicor does NOT keep track of inventory quantity (after any transaction, the on-hand value is reset to zero).

The Non Stock checkbox (unselected by default) means that Epicor assumes you want to consume existing inventory before buying/making more. Check the checkbox and Epicor will create buy/make suggestions on every demand for the part, regardless of existing inventory.

If I’m reading this thread correctly, you probably want to have the Quantity Bearing AND Non Stock checkboxes BOTH unselected.

I’m not sure that will fix this particular issue, but it might.

@Heide , look at your screen shot of the material on the job. To the left of the Purchase Direct flag is the lead time which is set to 15. If you zero that out, you should be fine.

Thank you so much. You have found my problem! The Purchase Direct with a lead time of 15 days caused the schedule to be bumped out. When I followed John’s advice @jkane and changed the purchase direct lead time to 0 days that fixed the issue. I also tried Ernie’s and Todd’s solution @Ernie @TDray of making the material have no check marks for non stock and quantity bearing. After saving the material changes, I re-pulled details and scheduled. That also solved my issue.

This problem is not just a one time issue for us. We have parts that the company would like to have on hand but not inventory. An example of these parts would be tooling or stencils (just like discussed above). In order to stop these parts from being inventoried we have use two approaches. One approach is to mark them not quantity bearing. They always have a 0 quantity and therefore do not get inventoried. We have also marked them as non-stock and only inventory stock items. But I now know that marking them non-stock will result in a Purchase Direct, add lead time to the parts, and push out the schedule.

How do other companies deal with parts that are on the bill of material but they don’t want to count in inventory (because they are expense items) and want to have on hand stock, like tooling and stencils?

I really appreciate all the advice that you have given. You are expanding my knowledge of Epicor. This has the possibility to clean up a repeating problem with our scheduling.


The best way to handle tooling and stencils is to create them as Resources. When you are building your MOM, you can add it as a resource on the operation. If you schedule, you will also know when they are being used and can handle conflicts.