Master Scheduling 1 parameters explained

Hi ​@eknock007,

The first key point for me to appreciate the S/P settings was understanding that MS first calculates what are known as “MS Proposals” i.e. what additional supplies do you need to meet your forecasted demand and remain above your safety stock. These MS proposals are seen as demand by MRP regardless of whether a supply is then generated.

The S/P settings determine whether these MS Proposals should go on to generate supplies (e.g. shop order requisition, purchase requisition, planned distribution order) for a planner/buyer to action.

Generate S/P Req Entire Horizon - All MS proposals generate supplies. Pros - good visibility of future purchase/production plan. Cons - lots of ‘noise’ that could confuse things, data overload etc..

Generate S/P Req - Only MS Proposals within the Planning Time Fence generate supplies. Pros - easy to see what needs to be actioned, Cons - less easy to see future plan (need to look at MS Proposals)

Do not Create S/P Req - Useful if you are manually planning your finished good production, but want to use the forecast to drive requisitions for components, sub assemblies etc. Demand for components will still flow down into MRP from the MS Proposals & actual supplies. E.g. if you manually create a Shop Order for the MS part, MS still sees this supply, so won’t create additional MS Proposals if your Shop Order already covers the demand from the forecast.

Create S/P req from MRP - Similar to above with the forecast driving component demand, but if you get a “real” demand for your MS part e.g. a customer order, then the supply for the MS part will be generated by MRP to cover this ”real” demand. E.g. perhaps your MS part has a short shelf life once manufactured, but the components have long lead times.

Time Fences - I always think that at a concept level, the PTF determines how manual/automated the generation of supplies should be. I need to balance the responsiveness of the system to change in demand vs the need for stability in the production plan.

Think of the extremes - if the PTF was set to 1 year, MS proposals would not recalculate in this period and the planner would need to review the action messages to spot all shortages/over supply and manually adjust the plan if there are changes to the forecast or customer orders do not align fully with the forecast.

If we set the PTF to 0 days, then we might come in tomorrow and find MS has generated a new MS Proposal for tomorrow and so MRP has generated requisitions for the components (say with a 30 day lead time) which are now all showing as overdue - i.e. we can’t actually respond to such short notice demand.

The PTF allows you to leave the longer term data to IFS to handle so you get good visability for capacity planning, purchasing planning etc but you then have full control of the production plan over a shorter period using the action messages to help make decisions. 

To add to the thorough explanation from ​@Katie, from my long-ago notes on the settings for Create S/P Req for when each setting is most applicable.

• Create S/P Req
  • Make-to-Stock, single Site
• Do Not Create S/P Req
  • Make-to-Order (plan the components ahead of the real order for the parent)
  • Multi-Level CTO (since you cannot create requisitions for DOP parts)
• Create S/P Req Entire Horizon
  • Supplier Schedules
  • Distribution Orders (multi-site), otherwise you don't see the whole picture
• Create S/P from MRP
  • Make-to-Order (plan the components ahead of the real order for the parent)
  • Single-Level CTO

Thank you both very for your responses. Good to know that there are people out there that seemed to understand the nuances of Master Scheduling.

We have been debating how the Generate Fix MS toggle works. We know it locks (fixes) values in the MPS field in Master Schedule by Part. Does it simply fix all MPS values inside the PTF and anything outside the PTF stays Proposed? At least that how we think is works.

We are under the belief that if the toggle is off everywhere that the Master Schedule will behave more like an MRP which maybe is what are looking to do because we have a business model that builds to stock and carry inventory (both raw and finished goods) based on a days of supply model. With everything in a Proposed state, we simply lock in (or Fix) the proposed supply signals that we need (i.e. PO reqs into PO’s, SO req’s into SO’s). Then like the MRP, let the Master Schedule recalculates everything and regenerate more supply signals if needed. Are we over thinking it?

So for now, we have toggled On the Fix MS flag at two demand sites, toggle it off at a supply site, but don’t know what to use at a site that is both a demand and supply site. We think the Master Schedule is doing the correct calculations at each site, but is there standard or more suitable way to toggle this flag at each site if it is important to toggle it the right way?