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. Time-Phased Planning is an ideal solution for this scenario. Materials that are planned using the time-phased planning technique are provided with an MRP date in the planning file. This date is set when creating a material master 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. The net change planning indicator is only utilized if the option for reorder point planning option is set in configuration for the MRP Type.
Here is some information regarding the calculation SAP uses to determine procurement proposals for time-phased planning. This approach assumes that forecasting and planning are performed in ECC, not SCM.
Material Forecast
First, it is necessary to unitize the material forecast component. If your goal is to construct a forecast based on past consumption, then standard SAP should suit your needs. However, companies are usually interested in basing the forecast on sales order figures – not on historical consumption – to more accurately capture customer demand.
Forecasting in Sales and Operation Planning (SOP) does not usually yield the desired results because CBP techniques, such as reorder point planning and safety stock, cannot be automatically calculated through the SOP forecasting routine. So the sales order figures must be sent to material forecasting for processing. To accomplish this, either leverage an existing information structure in SIS or create your own information structure that captures sales order values based on logic tailored to suit your needs; ideally it will contain a key figure representing the quantity which forms the basis of your forecast, and this key figure should be aggregated into periods that match your forecasting period (monthly buckets, for example). Make sure the update rules are activated for this info structure.
Next, implement exit EXIT_SAPMM61W_002 to populate the material “corrected value” consumption column based on the key figures in your information structure. During the individual or total forecast run, SAP will access this exit and update the ‘corrected’ consumption figures with the value in your info structure.
Time-Phased Planning in Consumption-Based Planning
Formula for determining the requirement quantity:
Calculating the requirement quantity based on a monthly forecast
- Daily forecast quantity = monthly forecast/work days in the month; for example (1000ea/21 work days).
- Requirement quantity = daily forecast quantity * interval period in days (cycle time + purchase processing time + 5/7*(planned delivery time) + GR processing time).
Notes regarding the time specification:
- Cycle time is in work days, and is derived from the planning calendar assigned to the item in the material master.
- Purchase processing time is in work days
- Planned delivery time is in calendar days and must be converted into work days by multiplying it by work days (5) per week / calendar days per week (7).
- GR processing time is in work days.
Reorder Level Calculation
Reorder level = safety stock + the requirement forecast within the replenishment lead time.
A month has 30 days in the case of external procurement.
Assuming a material with 0 safety stock, a monthly forecast of 200, purchase processing time = 0, GR processing time = 0, and a 7 day planned delivery time, the reorder level would be calculated as follows:
Reorder level = (0 + 0 + 7/30) *200
Time-Phased Planning in Material Requirements Planning
If you must incorporate planning requirements beyond forecasted values, it may be necessary to use MRP rather than consumption based planning. For example, this would allow you to include back order quantities or incorporate information from the sales team that lies outside the capabilities of material forecasting.
Time-Phased Planning with Requirements
In configuration for your MRP Type, set the flag “Time-phased planning with requirements (MRP)” to activate MRP-based planning instead of CBP-based planning. If you select this indicator, all the requirement elements are included in the net requirements calculation for time-phased planning that are included in this calculation for MRP.
Material requirements from the planning forecast are not calculated, so you will probably want to set “MRP indicator of forecast” = G, so that the system reads the forecast requirements. If you select this option, then it may also be necessary to set the material’s forecast splitting indicator to split the next two forecast periods into daily buckets. This will insure that if planning is executed outside of the standard planning cycle, the requirement quantity is accurately calculated from the forecast requirements.