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

Note: The system does not plan jobs or customer orders with a status of Stopped.

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.