Operation Scheduling

Just-in-time routings do not use overlap quantities or percentages to schedule operations.  Instead, each operation on the routing has an operation offset.  The offset indicates the number of days before the end of the process that the load will begin at the operation.  Each operation on the routing is back scheduled, based on the date when the item must be produced and the offset for the operation.  The following example illustrates how the scheduling occurs.

Operation 1:            Offset = 3
Operation 2:            Offset = 1
Operation 3:            Offset = 1

      |           Day 1    |           Day 2    |           Day 3    |          Day 4     |
      |                       |                       |                       |                       |
       Op1<-------------------------------------Op2<----Op3<----Quantity Due

The quantity is due on the fourth day.  To schedule operation 3, the operation offset (1) is subtracted from the due date (4) to determine the day when the load will begin on the operation (on day 3).  The labor hours and machine load defined on the routing step are multiplied by the quantity (or number of batches) to give the total load on the associated workcenter.  Since the operation takes one day or less, all load for the operation occurs on day 3.

Scheduling for operations 1 and 2 occurs using the same process.  Note that:

·     The loads for operations 2 and 3 both occur on day 3.  The operation offset is always subtracted from the end date of the flow schedule, rather than from the date when the next operation begins.

·     Operation 1 is scheduled to begin on day 1.  However, the load for that operation is spread equally over days 1 and 2.