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I have a question about the different calculations of the Shop Order Requisition start date depending on whether it is generated manually or through MS/MRP.

 

From testing (Cloud) I have found the following:

 

Manual SOR:

Uses Fixed & Variable lead time set on the Inventory Part manufacturing tab

If this is 0, it uses Manufacturing Lead Time entered on Lead Time & Supply Dates section on Inventory Part main tab instead

It doesn’t directly use the lead time data in the routing alternate revision

 

MS/MRP:

Uses lead time data in the routing alternate revision (if this has been calculated)

If not calculated, uses Manufacturing Lead Time entered on Lead Time & Supply Dates section on Inventory Part main tab

Ignores anything manually entered on Inventory Part manufacturing tab

 

If I change the Due Date on an MS/MRP generate SOR, the start date changes based on the logic for the manual SOR. So even if I change it back to the original due date, I now get a different start date.

 

Question:

Is there a reason the logic is different for the two methods?

 

The reason I ask is because the situation I am working with, the lead time has been calculated on some parts unintentionally.

 

The user would like all parts to behave the same, where they can control the SOR start date by manually entering Manufacturing Lead Time on Lead Time & Supply Dates section on Inventory Part main tab.

 

It seems if the lead time has been calculated, there is no simple way to achieve this if using MS/MRP (there seems to be no way to undo the calculation). You would have to create a new routing alternate revision?

Hi,

How do you schedule the start dates of the shop orders? Backward infinite scheduling? As I see it, it would make more sense to use same lead time calculation like we do in MRP, for manual Shop Order Requisitions. Because the way we are setting start date in MRP calculation is closer to how we calculating start date of Shop Order. For example, in MRP we do consider lot size based routings when setting the start date. We don’t do that for manual Shop Order Requisitions (on top of my head I think that is a bug). Example, the lot sized based routing alternate could have longer or shorter lead time than the * routing alternate. I think it has been forgotten, because in earlier versions of IFS, applications 8 and earlier we didn’t have the routing revision and routing alternate on the shop order requisition.

***

On the other hand I have quite often heard about more manual setting of manufacturing lead times because of “stuff is just sitting still and waiting and waiting at the shop floor”.

Cheers,

Mats

Thanks for the reply Mats,

 

I agree, the MRP calculation method is going to be more accurate to the Shop Order start date (you are correct they are backwards infinite scheduled).

 

OK so effectively I think you are saying manual SORs currently still use an “older” system logic to determine the start date as in earlier versions of IFS the routing information was not captured on the SOR. 

 

The situation I’m looking at, the user can currently set a lead time for the SOR manually by entering a Manufacturing Lead Time on the Inventory Part main tab. However, this is only because they have not run the Lead Time calculation.

 

They’ve run the Lead Time calculation on a few parts without realizing the impact, which means for these parts they get a shorter lead time that they want (as I would guess queue time, transport time etc. is not currently included in the routing). 

 

They do get a change in start date when converting the SOR to SO, but this is OK, as they are mainly concerned about converting the SOR in good time.

 

I suppose “Best Practice” answer would be the routing should be corrected and then all lead times can be driven from the calculation. However, this would be a big piece of work, so wondered if there was any way to cancel or undo the Lead Time Calculation after it has been run, so MRP reverts back to using the manually entered value on the Inventory Part?

Hi again Katie,

Just to be clear; queue time and transportation time is part of the routing alternate fixed lead time.

But you know sometimes the WIP is just sitting out there at the shop floor, just waiting, because things happens…

(queue time and transportation time does not affect the cost of the operation)

-Mats

Sorry when I said:

They’ve run the Lead Time calculation on a few parts without realizing the impact, which means for these parts they get a shorter lead time that they want (as I would guess queue time, transport time etc. is not currently included in the routing).

 

I meant from a data entry point of view, the user hasn’t added this info into the routing steps, so when they run Calculate Lead Time, it is shorter than they want it to be (i.e. shorter than in real life), so the start date is too late.

 

To get around this, they just don’t run the Lead Time calculation, which means when they run MRP it defaults to using what they’ve manually typed in on the Inventory Part page for Manufacturing Lead Time.

 

So the question is, if they do (accidently) calculate the lead time for a part, is there a way to undo this, so the system reverts back to using what’s been typed in on the Inventory Part?

 

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