Push planning

If the pull planning projects the order to be late, the Planner performs push planning. Push planning involves planning forward from the current time out to a projected completion date.

The Planner push plans an order according to this sequence:

• End-item quantity needed is calculated, and on-hand inventory is allocated to satisfy the end-item demand quantity.
• The remaining end-item demand quantity is passed to the components, down to the lowest levels in the bill of material. On-hand inventory is allocated to satisfy the component demand quantity.
• The components in the lowest levels of the bill of material are planned. Each operation in the component's route is planned in forward sequence (starting with the first operation). The result is the component’s earliest possible completion date, which will set its parent item's start date.
• Unallocated planned supplies are located, starting with the current date and searching out to the date calculated in the previous step. Supplies are allocated only if the entire quantity can be satisfied.
• When forward planning is finished, the end-item completion date becomes the demand's projected date.
• The system may plan non-critical operations earlier than they are actually needed to meet the demand. To optimize the plan, the system runs a series of additional pull planning iterations starting from the demand's new projected date:
  • The pull plan starts from the projected completion date. If this step projects a start date in the past, the system then pull plans the demand from the end of the plan horizon.
  • One or more pull-planning iterations is performed within a defined time window, dividing the window in half with each iteration until a feasible plan is found that is within the ALTPLAN.ITERDAYS (if this is a full plan regeneration) or ITERDAYSCTP (if this is a single-order/CTP plan) number of days of the need date. The beginning of the time window is always the demand's need date. The end of the time window will be either the projected completion date from the push plan or the end of the plan horizon (if the above-mentioned pull failed). For example, the first iteration pulls from the midpoint between the projected date and the need date. If that pull succeeds, the next iteration pulls from the midpoint between that new projected date and the need date. The process incrementally moves closer to the need date until it finds a plan that works (that is, a plan that doesn't calculate a start date in the past) and has a projected completion date that is within the specified days of the need date.