Work order operations are back scheduled from the MRP order due date. Back scheduling uses the standard operation setup, run, and move times along with work center queue and wait times. The scheduler can manually change operation start and end dates; however, these changes revert when CRP is recalculated. You can change operation time elements to increase or decrease operation times using Work Order Routing Maintenance.

MRP creates the work order release date by back scheduling from the order due date using manufacturing lead time. Because work order operations use routing times, order quantities greater than the standard order quantity on the item master can push the first operation start date out past the order release date.

If the operation start date is before the order start date, the message “Op Conflict” (operation conflict) is generated in the Capacity Requirements Planning (CRP) recalculation report.

The scheduling algorithm considers operation overlap. Overlap specifies the number of items requiring completion before the next operation can begin. The overlap quantity can be specified in Routing Maintenance.