I’ve read many posts about constrained materials, but I can’t find one that clearly answers these two questions: Do constrained materials work for manufactured parts on BOMs? If so, does that REQUIRE you to select either plan as or pull as assembly on every non-purchased material?
We currently have our make part materials stocked and we only have “view as assembly” checked on the BOMs. The start dates on our jobs are not aligning with when the constrained materials will be available. Can someone provide some insight into this? Thank you!
That post you sent is helpful. Here’s a follow-up question: If the statement made in that post is accurate, that selecting neither plan nor pull as assembly means the assembly is consumed from inventory, then why wouldn’t constrained materials still work? That should mean that you get an mrp job suggestion for the material, and the next level job can’t start until that material is stocked. What am I missing?
From post you sent:
“None selected [Plan or Pull as Assembly]: assembly is consumed from inventory”
Great question. Can’t say I know the answer for sure, but this is my understanding of how the system works.
The system wants to look and see when the material will be available based off of the CTP calculation. When it calculates a date that material will be available, it will then schedule the job based on that date. If the system does not know how that material enters inventory, it cannot run CTP to calculate it. If it was a purchased material with a lead time, it would calculate it based off of that. For a manufactured part, it would continue drilling down to the bottom to figure out how long it will take to manufacture. Not selecting Pull As or Plan As does not provide the system the information to run CTP. It hits that part and says “I don’t know how this part is supplied, so I’ll just stop right here”.
I guess a simpler way of saying it would be that you are not providing the full instructions on how you operate to the system, so it can’t provide the information you want back.
Thank you for the clarity on this! I get what you’re saying, and unfortunately it feels like a major hole in the system. I would think MRP should be able to work for the “assembly is consumed from inventory” option without the need for job to job connections.
Do you have a recommendation then for how we should handle the large lots of materials we bring in (for the economy of scale and single lot traceability)? We for example may make 100 pieces of part A that will go into stock and then be issued to 20 different 5 piece jobs. My understanding is that if we use plan as assembly then we will get individual job suggestions for each separate need, rather than relying on days of supply to drive a 100 piece MRP job for part A.
Well, if you have job lot sizes set, then regardless of what was required, it would always cut a job for that quantity.
So in your example, you have 10 of Part A in stock. You get demand that needs 20 to complete the job. If you have a job lot size of 100, MRP will cut a job for 100 to stock.
Also, days of supply should catch the disparate demands and lump them together too.
I may not have explained properly. I meant if there is demand for 100, but no lot size. The question is how do we have to set up our MOMs and parameters so we get MRP to give us accurate start dates on the job.
With your example if we have 10 of part A in stock and we need 10 more to issue to the next level job that requires 20, the system will successfully make that 10 piece MRP job for us. The issue is that the start date on the job will say today if all purchased materials are fully available. We want the start date on the job to reflect the due date of part A, since we need that material. We haven’t turned on plan or pull as assembly yet because of our larger lot sizes supporting multiple higher level jobs.
Mark all of those parts as Plan As and set your days of supply. That should create 1 unfirm job for whatever the quantity is that falls in the days of supply at the earliest need by date.
MRP will not create a linked job unless Part A is marked as Non-Stock. Plan As does not actually create the links between jobs, it only creates a separate job to meet the demand. And setting days of supply should consolidate them.
Thanks again, John! We have found two good examples and will make the change in a test environment. Hopefully running a net change on the finished good level of the two affected parts will show the change.
Hello again. Unfortunately making the change did not affect the parts at all. They both still show that the jobs can be released even though the material is not yet available. There are expedite suggestions on the materials, but those are there with or without the plan as assembly box checked. At this point I’m still not sure what the plan as assembly flag does for make to stock materials.
Did you just make the change and re-run MRP/Scheduling? I always forget to mention that you have to un-schedule every job and then run MRP Regenerative.
Thanks for continuing to respond. We have run full MRP regen and global scheduling at this point. Also, we were only dealing with MRP jobs so there was nothing to un-schedule. The results are unfortunately still the same. We are going to try to update all make parts to plan as assembly for the whole BOM as a last attempt. If there’s anything else you can think of that we are missing please let me know.
As an update - it is now doing something! I can’t believe I didn’t check it earlier, but those two parts coincidentally had zero values for manufacturing lead times. I’ve updated them and run MRP and Scheduling, and the material now shows as a subassembly on the job (because the part was needed within lead time). Although not ideal, this isn’t terrible if it only happens when the part is needed within lead time. However, I didn’t like the way it basically disappeared in time phase. Is there somewhere else I should look to better see demand for subassemblies being pulled in because of plan as assembly materials?
Sorry, I missed your last response from a couple of weeks ago.
I was concentrating on the constrained material part of your question and forgot about a setting to use. Re-reading reminded me.
I believe there are 3 settings you need to check.
Are the subassembly parts marked as Plan As on the parent part.
Is the subassembly part marked as Non-Stock on the part record.
Have you turned on Multi-Job at the Site level.
Multi-Job is the functionality that looks at the complete MOM and creates all of the jobs required to make the final assembly. Plan As and Non-Stock is what will make the system create separate jobs.