If a vendor always delivers a material on a particular day of the week, it makes sense to plan this material according to the same cycle in which it is delivered, but displaced by the delivery time. This is possible with the time-phased planning procedure.
If a particular material is to be planned using this procedure, you must set the MRP type for time-phased planning and you must enter the planning cycle in the material master record. You enter the planning cycle in the form of a planning calendar in the Planning cycle field. You must also define a planned delivery time and the Lot-for-lot order quantity as the lot-size key.
You can also use the optimum lot-sizing procedures for time-phased planning. They are used here in the same way as in
Materials that are planned using the time-phased planning technique are provided with an MPR date in the planning file. This date is set when creating a material master record and is re-set after each planning run. It represents the date on which the material is to be planned again and is calculated on the basis of the planning cycle entered in the material master record. For materials that are planned using the time-phased planning procedure, the two indicators, the total change indicator and the net change planning indicator are irrelevant. Therefore, they are not set by the system even if changes that are relevant to the planning run are made.
By using this planning technique, you can set the system so that it only plans materials on specific pre-defined days. For example, if you assign the same planning cycle to all the materials of a particular vendor, the system will always plan these materials on the same day. The purchase requisitions that are created in the planning run to cover material shortages can be processed, per vendor, by the MRP controller in the SAP purchasing system.
If you use the SAP Merchandise Management System, the system proposes the planning cycle from the vendor sub-range when you create a material master record. The vendor sub-range contains all the goods of a particular vendor that, from a logistical view, can be planned similarly.
You can also enter an MRP date during the planning run, meaning that you can bring the planning run forward to an earlier date, if necessary. For example, if the planning run is set for Monday, you can bring it forward to Saturday instead.
What Happens in the Planning Run?
The time-phased planning procedure has been developed as a consumption-based planning technique. Therefore, you must carry out the forecast run before you carry out the planning run. The forecast calculates the future sales (requirements) quantities. It also calculates the safety stock if this is defined in Customizing. Then, you can carry out the planning run.
Once you start the planning run, the system uses the MRP date recorded in the planning file to determine which materials are actually to be planned.
The system uses the interval between the MRP date and the availability date of the next MRP date for the requirements calculation in the planning run. Existing stocks must cover this interval. You must bear in mind that if nothing is ordered at the first MRP date, you have to wait for the next MRP date before you can plan and order this material again. Therefore, if an order proposal is created during this planning run, it will not be available until the end of the interval.
In the requirements calculation, the system compares the forecast requirement quantities with the actual stock and the firmed receipts in the interval in question and calculates how much more is to be ordered, if at all. The requirement quantities of the periods that lie completely within the interval in question are taken into accout in total. On the other hand, the requirement quantities of the periods that only partially fall within the interval in question are only partially taken into account. If you have specified a processing time required by the purchasing department, it is included in the requirements calculation.
The requirements are calculated using the following formula:
The planned delivery time is included in the calculation in the calendar days and the purchasing department processing time and goods receipt processing time in workdays.
If, within the interval, the current stock plus the open order quantity (firmed receipts) is smaller than the requirement quantity, the system creates an order proposal for the difference.
In this calculation, the system presumes that the firmed receipts all lie within the interval in question. Whether the firmed receipt is available at either the beginning or at the end of the interval is not relevant. This means that a temporary shortage may occur; this is tolerated.