Master schedule / Planning Methods

Thanks for the reply Saman, 

I find it odd that MRP and MS logic is so different. Just because a part has independent demand and needs to be forecasted, shouldn’t mean planning methods wouldn’t apply. Is there a way to forecast independent demand and have MRP completely run the show?

I’d like to read up on it more but the link isn’t working for me. 

Thanks,

Eric

Hello Eric and Saman,

In MS we have our Time Fences, DTF and PTF and it is only beyond Planning Timefence system could behave a little bit more like MRP. Coz inside PTF master scheduler is king. It is a tricky balancing act to be very flexible to customer demand changes versus production stability. Please bear in mind, if there are many changes in the Master Production Schedule this will of course be amplified down through the BOM in MRP.

Let say for a moment that we could use the dynamic planning methods like G and E for master scheduled parts, then you know when system generated MPS receipt is aged within the PTF and becomes fix. In the same level 1 calculation run, you can get a new system generated MPS receipt just outside the PTF. It does not feel sooo much like Period Order Qty (G) or Least Unit Cost (E)...

Nevertheless - I still kind of agree with you Eric that we should support different planning methods and then let our customers to decide.

Finally a tip for creating a less nervous MRP system:

1. Work with time fence policies
2. For the master schedule parts try to use fixed lot sizes, it may help reduce a lumpy demand picture down through the BOM in MRP
3. For sub-assemblies try to use L4L and lot sizes as small as possible to avoid amplifying bullwhip effect
4. Then for purchased parts - there you can use E, F or G
5. Educate the users in IFS MRP

Have a nice weekend!

-Mats

Hi Mats, 

Thanks for the reply. Please consider this scenario:

• Forecast for 25 on 3/15/22
• Forecast for 25 on 4/1/22
• Forecast for 25 on 8/1/22

Orders have a high fixed setup cost so it doesn’t make sense to manufacture 25 twice within a month. How could MPS generate supply for 50 due 3/15, and 25 due 8/1? I don’t think time fences will resolve the problem since we’ll just get individual 25 pcs requisitions as they cross the PTF. Setting a min of 50 doesn’t work, or we could end up carrying an unneeded 25 after August. A least unit cost or period order quantity strategy would work and an EOQ method would even tell me if it makes more sense to build 75 now, and carry the additional 25 for 4 months. 

Okay you have some high setup cost.

May I ask you how long time ahead your are getting/entering your customer order lines? And how that relates to your planning timefence?

And the forecast scenario you outline above - is it a typical scenario? You sell some stuff in March and April, and then there is a break until August? I am just curious.

Anyway good that I got eyeopener for your problem.

Thanks a lot for an interesting discussion Eric!

Cheers,

-Mats