Production planners have to make sure material is available when needed. MRP assists production planners with this task. The MRP run determines expected material shortages and creates planned orders, purchase requisitions, or delivery schedule lines to cover the expected material shortages. A shortage exists for a material if the material is subject to demand-driven planning and if the total quantity of material requirements (sales orders, stock transfer requirements, production requirements, and forecast requirements) up to a certain point in time exceeds the total quantity of material receipts (inventory, production orders, purchase orders, delivery schedule lines, firmed planned orders, and firmed purchase requisitions).
SAP S/4HANA features MRP Live; an MRP run optimized for SAP HANA. MRP Live reads material receipts and requirements, calculates shortages, and creates planned orders and purchase requisitions all in one database procedure. This minimizes the volume of data that has to be copied from the database server to the application server and back, which considerably improves performance. MRP Live has some additional advantages including the following, for example:
- The definition of the planning scope is more flexible. MRP Live allows you to plan a set of materials with all components, materials for which a certain production planner is responsible, or one material across all plants.
- If a material is transferred from one plant to another then the stock-transfer requirement is not known in the supplying plant until after the material has been planned in the receiving plant. MRP Live determines the sequence in which materials have to be planned across several plants.
- MRP Live is a prerequisite for the future production planning and detailed scheduling PP/DS solution in SAP S/4HANA.
Classic MRP is still available as an interim solution. MRP live differs from classic MRP in the following aspects:
- MRP live does not write MRP lists.
- Multi-level, make-to-order planning (transaction MD50) is not optimized for HANA.
- Individual project planning (transaction MD51) is not optimized for HANA.
- The creation indicator for purchase requisitions is not available in MRP Live. MRP Live always creates purchase requisitions if the material is procured externally.
- The creation indicator for delivery schedule linesis not available in MRP Live. MRP Live always creates delivery schedule linesif a valid delivery schedule exists.
MRP Lists
MRP lists were intendedfor checking the MRP result. MRP lists were used to find materials with issues quickly.MRP lists aresnapshots of the material supply and demand situation at the time of thelast MRP run. The snapshot is often outdated. With HANA, stock/requirements lists can be read with high speed. The MRP apps determine materials with issuesin real-time.In SAP S/4HANA there is no need for outdated MRP lists.
Planning of individual make-to-order sales orders and projects
Multi-level, make-to-order planning was a performance measure only. Rather than planning all planning segments, the system only planned a selected planning segment. Thanks to the speed of HANA, it is no longer required to support this performance measure. Thisalso makes the MRP run simpler.
Creation indicators
Classic MRP has acomplicated set of rules for instructing the MRP run to create either purchase requisitions or planned orders for externally procured materials. A similar set of rulesinstructs classic MRP to create delivery schedule lines, purchaserequisitions, or planned orders for externally procured materials with valid delivery schedules. Creation indicators are defined in MRP groups, on the initial screen of the MRP run, and default values are defined in the code. This is a complex logic with very limitedbusiness value. Planned orders for external procurement have to be converted into purchase requisitions eventually.Creating planned orders first and converting them into purchase requisitions isan unnecessary process step.
Creation indicators were originally intended to separate theresponsibilities ofproduction planners and purchasers.Production planners were responsible for planned orders and purchasers were responsible for purchase requisitions. Today the roles of production planners and purchasershave changed. Purchasers very often focus on negotiating contracts with suppliers while the operative creation of purchase requisitions and purchase order handling is left to material planners and MRP.
Therefore MRP live always creates delivery schedule linesfor externally procured material with valid delivery schedules and it creates purchase requisitions for all other externally procured material.
In SAP S/4HANA the planning file was optimized for simplified update logic, consistency and for update performance.
