Hi guys,
I’ve got a query about how to use APB. An example is apt here.
Consider an MPS consisting of 2 items. Lets stipulate the structure for each is: Level 0 = end-item (GA), Level 1 = SA (x2), Level 2 = 4 piece parts & Level 3 = 10 piece parts. Let’s also imagine 0 overlap between recipes (thus no requisition to merge supply).
The relevant ‘Priority Rule’ is ‘Earliest Possible Due Date’ (with all operations selected) since we’re looking to schedule both projects to finish asap, with no spare capacity gaps.
2 options arise at this stage. Either, schedule both project items (under the priority rule stated) in APB with a single executed run. Or, load the initial project (specifically, the parts therein) and execute the engine. Then, do the same for the next project, but exclude all operations that are released and started, thereby ignoring the orders under the first project. Note, a presumption is there’s no ‘MPS confusion’: insofar as the initial project is of greater priority, it’s given an earlier ‘Required Date’. Plus, such dates meets a plausible (actual) lead time.
In our current practice, we’re doing the latter. This is equivalent to a time-fence: ‘for any active order that have Ops released and CBS scheduled - don’t include it within the remit of one’s present APB run.
This is because APB ‘mixes’ orders between projects when executing it in the first way. Especially in instances of re-scheduling.
So, to put it like this, if I wanted APB to re-schedule pieces for project #1, and only then, seek to allocate parts under project #2 to their requisite resources, how can this be achieved? The expectation is to be able to re-schedule along this logic once a project is in WIP (alongside other projects with started orders).
I argue Need Dates are not ( at least alone) sufficient based on their calculation logic which suggests they’re not intended for the purpose described. What can, then, adequately convey MPS priorities at the lower-levels such that if you have 2 piece parts competing for a resource, APB should prioritize the part belonging a project with an earlier top-level Required Date (all other things being equal).
I want to dispel some potential concerns.
- The MRP Action Report for ‘Early...’ & ‘Late Orders’, which otherwise enables us to alter Need Dates in a systematic and considered way, is not useful here. Because it re-aligns the Need Dates within a project (i.e. said level 3 item must have a Need Date before said level 2 item, since material for L3 must be in sooner, logically speaking). It remains silent on changing Need Dates across projects, in a comparative way.
- It could also be said you’d want ‘some’ (perhaps not all) piece parts for the project #2 to begin ahead of those in project #1, if (and only if), it produces an ‘optimal resource trade-off’. Namely, it prevents a resource sitting idle, and more importantly, you don’t, in fact, negatively affect the finish date of project #1 whilst receiving said piece part for project #2 earlier, by extension project #2 (in full) sooner. So it’s win-win!
This may be true. I suspect it’s not, namely if both projects are subject to the same constraints (re-asserting the ‘all other things equal’ clause).
So, returning to our initial question, what tools are available for this preferred scheduling strategy? So that we can run APB in the first way, whilst avoiding a mix-up. What data, or inputs fields, can be leveraged to guide APB in the desired way?
Sorry for the length of this post! I tried to be economical with my prose, but there is a lot of moving parts for this problem case!
Many thanks,
Jay