We have a make to order enviroment, that means our production orders are created (and scheduled) directly from the sales order. The sales gets back a confirmed date and quantity from production order scheduling - and here this GR processing time is also added. Absolutely useless in this scenario, but MM needs this GR processing time for the external procurement of the material.
I'm hearing at least two problems here. Let me lumber through them as I see them.
#1 - We have a make to order enviroment, that means our production orders are created (and scheduled) directly from the sales order. The sales gets back a confirmed date and quantity from production order scheduling - and here this GR processing time is also added. Absolutely useless in this scenario, but MM needs this GR processing time for the external procurement of the material.
The GR processing time is quite legitimate, and needful.
It represents the time it takes once a material is 'delivered', before
it is usable. If that is instantaneous for you, then this field is blank.
In fact if it is less than one day, the field should be blank. (MARC-WEBAZ)
If you DO have to do testing or documentation or even just 'checking' to
be sure the proper certificates
have arrived with this material, then it's nice to have
a day here for this. --- I may have overlooked one thing, if you are ONLY
thinking of the FERT that your customer ordered, then maybe this field
seems trivial. However, if your process requires that the FERT be purchased
from some other company (or even supplied from within YOUR company), then
there IS a receiving process that has to happen . . . it does take time
to back a truck up, get a fork truck to unload it, the
identification process, and then relocating the item
to where it can be shipped to your customer.
Also, if you produce this item, then there are 'other' items that need to be 'built' into this item . . . THEY need the GR field, even if you produce the saleable item, it has to be 'received' from production into inventory for you to ship it out.
There is another field that should be considered. This is the procurement lead time. The time it takes for purchasing to "react" to the requirement. When the sales order is placed, the signal will come for 'purchasing' to occur (via MRP perhaps). Purchasing MAY take as long as a day to get that order to a vendor where the vendor can now react. This time is generally a 'standard' time for any given plant/purchasing org and is included using OMDT.
Thirdly, the vendor lead time has to be considered. This is what the field "Planned delivery time" (MARC-PLIFZ) is about. The vendor's turn around time - from the time they are notified of your intention (via a PO perhaps), until they can put it on your dock . . . that is what this field is about. And MRP knows the difference between this field and the others. Between the three fields mentioned, the 'purchased' item is properly planned for . . . except for the exceptions and the fact that this is all based on "norms" and averages which never seem to be exactly what is needed, but that's another discussion .
Next we think of the situation where the item requested is produced by us. In this case (as mentioned before), the GR is STILL legitimate - perhaps not needed if it takes less than a day for your company to receive material from production, inspect it, certify it, and load it up.
However, a "0" is a legitimate entry to this field.
What is also needed is a place to locate the time for "producing" this item. That is where there are options. One option in MRP 2 is the field "in-house production" (MARC-DZEIT). This is sometimes useful, but dangerous. It assumes that no matter how large an order is or how much of a material is needed, it can always be produced in the same period (in 'days', of course). The number of days fits in this field.
If that doesn't 'do it' for you, you can go to the "Work
Scheduling" view of the Material Master and include the details for the
fields under the "in house production time in days" grouping (Setup time;
Interoperation; Processing time; and base quantity). At LEAST this gives
the system a 'shot' at planning longer times for greater quantities. If
you fill both data points in (in
house production time and " in days, the 'in days' will
supercede the other).
Now you've put in all the data that you HAVE to input to have the system plan the length of time needed for telling your customer when you will have their product ready for them.
In the case of your conflict where you produce OR source the item, then you MAY have a problem with GR - look at both scenarios and see what your entry should be. You CAN use the Total Replenishment Leadtime (MARC-WZEIT) field to be the TOTAL TIME when producing the material in-house, because the external replenishment does not look at this field. So MRP will run and depending on how you have it set, it will consider purchasing the material, or making the material, and the fields we've mentioned will impact the result as mentioned.
