About Pull Planning

Pull planning is the process APS uses to backward plan a demand from its need date. Starting with the last operation in the end item's routing, the system searches for available supplies (such as purchase orders), inventory, and/or resources to complete the demand on time. The pull-planning process follows this sequence:

• Search backward from the demand's due date to allocate planned supplies of the end item. If sufficient planned supplies are available to satisfy the demand quantity, the planning is complete.

• For any unsatisfied demand quantity, search backward from the due date to allocate on-hand inventory. If sufficient inventory is on hand to satisfy the demand, the planning is complete.

  Note: When APS allocates inventory to a demand, it considers the combined total of all inventory at all warehouses (at a given site) in which the Dedicated Inventory option is not selected.
• If the previous two backward searches do not satisfy the demand quantity, search forward from the demand's due date plus the time defined by the Supply Usage Tolerance value. In this situation, where the system must allocate planned supplies within tolerance, it allocates as much of these tolerance supplies as possible before allocating earlier, non-tolerance supplies or on-hand inventory.
• For any unsatisfied demand quantity, create a planned order. The type of item determines how the system creates the planned order:
  • For Infinite Items: The system plans the demand at the request date and assumes it to be satisfied. If the Infinite field is selected on the Items form, the item is not constrained by resource capacity or lead time, and is assumed to be available immediately.
  • For Purchased Items: The system checks the item's lead time to determine whether you can obtain the item by the due date. If so, the system creates a planned purchase order and planning is complete.
  • For Manufactured Items: Manufactured items are planned differently depending on whether the item has a routing and whether the Planning Mode is Infinite APS or APS:

    Does item have a routing?	Infinite APS Behavior	APS Behavior
    Yes	Infinite APS pull plans the operations through the item's routing, starting with the end item's last operation. It determines the operation start dates by summing the Move, Queue, Setup, Run, and Finish times defined for the operations and assumes infinite resource capacity. After pull-planning the item through its routing, Infinite APS pull-plans the item's components. The setting of the Plan Materials at Operation Start field determines how the system sets the need date of a component requirement; if the parameter is selected, the need date of a component is the start date of the operation in which it is needed. If the parameter is cleared, the need date is the start date of the job.	APS plans the operations in the same manner as Infinite APS in almost all respects.   The difference is that APS considers the finite availability of your resources. APS checks several combinations of resources to find the fastest combination. The Pull Iterations planning parameter determines how many combinations to check.   This planning method is much more realistic in that the system does not over-promise an order during a period when there are actually no available resources to complete the order.
    No	Infinite APS calculates the lead time for the end item. To determine the start date, Infinite APS plans backward, starting at the due date, to the lead time value. Resources have infinite capacity.	No difference from Infinite APS. When APS plans an item that does not have a routing, the item is treated as if the MRP Item option (on the Items record) has been selected for that item.

• For Transferred Items: For information about how transferred items are planned, see About Global Planning.

  If, at any level of the BOM, the system cannot plan the operation with enough time remaining to plan all remaining previous operations, the pull-planning fails and the system instead push plans the entire demand (see About Push Planning for more information).

• If the item has a value specified in the Order Minimum field on the Items form, and the planned order quantity (the quantity the system plans to make or purchase) will satisfy the entire demand quantity, the system frees the supply and inventory allocated in step 1.