For this type of scheduling, all the operations of a selected WO are sequenced before considering another WO. In this case, the schedule can be done as follows
•by forward scheduling, which consists of sequencing the operations as soon as an available slot is found that is large enough to place the operation,
•by backward scheduling, using the WO due date, the operations are sequenced in reverse order.
In both cases, the global sequence following which the different work orders are scheduled must be given. First, the released work orders are automatically scheduled before the planned work orders. Second, a priority index can be attached to each work order. This priority index is a major sorting criterion. Finally, sorting criteria can be defined. The scheduling menu proposes nine sorting criteria:
•Order number: the work orders are sorted by increasing number
•Release date: the work orders are sorted by increasing release date
•Due date: the work orders are sorted by increasing requirement date
•Lowest number of operations: the work orders are sorted by increasing number of operations
•Greatest number of operations: the work orders are sorted by decreasing number of operations
•Greatest total load: the work orders are sorted by total decreasing load (sum of the machine time allocated to machines)
•Least total load: the work orders are sorted by total increasing load (sum of the machine time allocated to machines)
•Slack: the work orders are sorted by increasing slack (the slack is calculated during the infinite capacity scheduling).
•Random: the operations are sequenced randomly.
One of the sorting criteria has to be selected from the pull-down list.
A forward schedule is always performed on a released WO.
When a backward schedule is requested, if it is not possible to sequence all the WO operations, then the procedure tries a forward schedule.
If the Overlapping planning option is activated, the finite capacity scheduling procedure will also use the overlapping.
The work orders that cannot be totally sequenced before the due date are de-scheduled and appear in the Not Scheduled Firm WO List.