In a previous post, I touched upon running MRP with parallel processing. So to continue with the MRP processing topic, let’s look at another: processing with basic dates or lead time scheduling. This type of processing is used whether you schedule planned orders by way of the routing or in house production time for the given material. If you choose not to use the lead time scheduling and capacity requirements setting (setting number 2), then you are left with the basic date scheduling (setting number 1).
Most instances of using basic date scheduling that I have seen is that it is run using the in house production time. This is simply one big bucket of days that it takes to produce the material. Although this is a very quick and simple way to run MRP, it is usually based off a number converted from a legacy system.
Converted lead times are usually not all that indicative of the process and is typically a common value used across a group of materials. Over time, this value usually becomes inaccurate as compared to the process. There is a better way to use basic date scheduling with a seldom used but effective function;
using the routing as a basis for updating the material master.
Your engineering and planning staff can easily perform this function directly from the routing using the scheduling feature on the routing. This scheduling function will afford the accumulation of setup, processing, and teardown standards as well as the various queue times. From this accumulation of the standard values, the material master can be updated to provide a more accurate basic date scheduling than can be had using the in standard house production time found on the MRP2 view. When the material master is updated with these values, MRP will instead use the setup, processing, and tear down times versus the in house production time for use in determining the basic dates for scheduling planned orders.
So how does this update to the material master work? From the change routing (CA02) or the engineering workbench (CEWB) transactions, by way of the menu Extras > Scheduling > Schedule, you can begin the process of accumulating the standard values. Today’s date will default and you will need to supply the Lot Size and any reduction type information if desired.
After clicking the green check mark, you will need to identify the overview variant. I always select the first one on the list, operation segments. To continue, click the green check mark.
Next you get a Scheduling Overview screen from this function. This screen lists each operation and can be used as sanity check prior to seeing the end result.
By clicking the Scheduling Results tool bar button; you will now see the final results. My example shows that material has a general in house processing time of 15 days, but after my scheduling from the routing, I have a total of 11 days. Note that the system rounds up to the nearest whole number of days (5.33 processing + 0.95 setup + 4.32 interoperation = 10.60 days), but the material master will use the component entries as you will see further down this discussion.
Once you feel this function has the desired results, click the Update mat. master button and you will receive the message: “Scheduling data marked for material master update”. This indicates that the update to the material master is ready for final processing. It does not directly update the material
master, but rather sets a table entry to final process.
The final step is to either run transaction CA96 to update the material master directly, or CA97 to schedule the update for a time in the future. The CA96 transaction will list each and every material awaiting update of the respective material masters. Manual updates of individual fields are available if desired. When ready, select the materials you want to update then click the Update mat. master tool bar button.
Now you can do a check of the material master using MM03 to display your results on the Work Scheduling view. This now completes the update process from the routing to the material master for material requirements planning.