About the Planning Process
When the system plans a demand, it first searches backward from the due date to allocate the needed quantity (this is "pull planning"), and calculates the start date for the demand. In some cases, the system may not be able to plan the demand in the time between the due date and the current date, and the start date is calculated to be in the past. In this situation, the system instead plans the demand forward from the current time (this is "push planning").
Simultaneous Requests for the Same Resource
When two operations need the same resource for the same time period, the system adjusts the planned time of the lower-priority demand to avoid the conflict and to ensure a realistic plan.
Material Components
Material components required in the production process are either purchased, manufactured, or transferred from another site. When planning the end item, MRP and APS assume that all required components are available at the start of the job or operation where they are needed, depending on the setting of the Plan Materials At Operation Start planning parameter.
Dynamic Reallocation by Order Priority
When the system allocates on-hand inventory and planned supplies to satisfy a demand, that allocation is considered temporary until the demand is scheduled. . Consequently, when you run the APS Planning activity, the system treats that inventory and supply as available for use, and reallocates it according to the ranking of the order's priority type defined on the APS Order Priority form.
Each priority type, such as "Order Entry Demand" or "Forecast Demand," has an assigned priority value. Order types with lower priority numbers consume available capacity before order types with higher priority numbers.
Demands and Supplies
A demand is a requirement for a quantity of an item. Supplies (also called receipts) are transactions that add to the available quantity of the item that can be allocated to a demand. To satisfy a demand, the system first allocates available supplies and/or on-hand inventory. After allocating supplies and on-hand inventory, if any quantity remains unsatisfied, the system creates a planned manufacturing order, purchase order, or transfer order.
Demand Types
A demand may be any of the following system transactions:
- PJOB Parent job
- PMPS Parent master production schedule
- PPS Parent production schedule
- PPLN Parent planned order
- PREQ Purchase order requisition
- CO Customer order
- FCST Forecast
- TRNS Transfer shipment
- TPLN Planned transfer
- MPS Master production schedule
- SSD Safety stock
- PROJ Project demand
The system plans all requirements for a given demand before it considers the next demand.
Supply Types
A supply may be any of the following system transactions:
- JOB Job
- PO Purchase order
- PREQ Purchase order requisition
- PS Production schedule
- MPS Master production schedule
- PLN Planned order
- TRNR Transfer order receipt
Planning Flow
For a flow diagram detailing the planning algorithm, see APS Planning Algorithm Flow Diagram, available for download on the support site.