Hi Katie

There are relics in the documentation here from the 1990s! A decade where Soviet Union fell and the rise of Internet… Back in 1996-1997 we came up with the predecessor of Production Line, which we called Manufacturing Cell. The parts connected to a Manufacturing cell behaved like planning method M - no MRP explosion.

Later we re-engineered the Manufacturing Cell solution into Production Line and Production Schedules.

Some old relics of the Manufacturing Cell documentation have survived through the decades. This is what you have seen here.

So we have a documentation bug :-(

MRP happily explodes through all MRP planning methods except M. (And planning method B, C and N are examples of planning methods not even visible to the MRP engine)

In your case your are using the Inventory Part Planning setup “Do Not Release”. MRP will still explode as you have noticed but it will not create shop order requisitions for you.

You can see those internally MRP planned supply in the Gross Req tab above, and as you can see they don’t have an Order No (there is no shop order req behind it, no non-firmed production schedule receipt either)

On top of my head this is kind of a nice feature. On thing that came to my mind here in the December darkness, is that these MRP internally planned supply doesn’t contribute to CRP load calculation. Perhaps that can be fixed… I am not sure.

Cheers!

-Mats

Thanks for the explanation Mats, it seems I found some dusty, hidden corner of the documentation then! The system is behaving exactly how I want it too, I was just nervous about going ahead without understanding the contradiction in the page help, but that’s all clear now.

In this example, the manufactured MRP part is set to “do not release” as the planning for this is happening offline. The offline process is pretty much replicating planning method C for the manufactured part, as the biggest constraint in this process is storage space. The supplies proposed by the external calculation are then raised as Shop Orders in IFS. There is a desire to bring this part of the planning into IFS too, but we can’t use method C without losing the neat demand explosion to the purchased components that we can get when it is MRP controlled. Unless there a method you know of to achieve both? 

Interesting about the CRP too - in all the scenarios I have come accross so far when ‘do not release’ is used the supply is being manually/externally created so CRP is only considered at the point when the ‘real’ supplies are entered, but I could see it could be useful to check in advance of this.

Hi Katie,

We can achieve Min-Max behavior using DDMRP, planning method H.

But, should you really start using DDMRP?

One thing here to keep in mind that DDMRP’s forward visibility is basically just one lead time ahead. If you start using DDMRP for sub-assemblies, you will loose the long term exploded forecast from your MS Level 1 top part.

Anyway… I still outline a potential setup:

So here I manually enter my red zone buffer and my green zone. I set the yellow zone to 0. So all of a sudden I have two zones in DDMRP, which shows up in the graph above.

The red zone becomes the MIN - the “order point” (in this example 50pcs), and the red zone + green zone becomes the Max Level. In this case 50+200=250. So 250 represents my storage limit in your example above.

Okay…

So when I run DDMRP (MRP) and I have 40pcs of this part then the net flow equation will give me this:

Net Flow = onhand + open supply - (open demand until today + sum of qualified spikes in the future)
Let say in this example I only have 40pcs on hand, and no open demand and no open supply. Then the net flow = 40. 

And if net flow <= top of yellow = 50 then we will order more.

And we will order like: top of green - net flow = 250 - 40 = 210 (it is important to not setup any multiple lot size)

Kind of nice.

But you have to think if you can use it here…. I am not to optimistic. The future visibility problem AND that the organization should learn and adapt to something new.

Best Regards,

Mats

Thanks for the detailed reply Mats - DDMRP is on my list to fully get my head around (I was reading another thread where there is a mini training session just the other day!).

This is clear and I can see how it is a nice solution for MRP min/max… I’ll need to get a better understanding of the lead times through the BoM I think to see whether losing the extended future visibility will be a problem for this particular scenario. In any case it’s a useful example to have in my memory for other projects.