Scheduling and Lead Times
In some situations, different products manufactured on a line have significantly different lead times. Even if flow rates are similar through most of the line, some products might spend more or less time at an operation—for example, products that are burned-in, dried, aged, or cured.
When a line is changed over from processing one product to another with a significantly longer lead time, the line’s output is interrupted by the changeover time plus the new lead time. This might not be important if you are manually determining the due date for expected output from a line. But if the system encounters a scheduling conflict and reschedules due dates, these dates will not take into account the new lead time.
There are two ways to avoid this:
• Assign due dates manually and then monitor the line schedule to see if any due dates following a changeover have been automatically rescheduled.
• Increase the changeover time to reflect the increased lead time between two products. This way the changeover time reflects the total time a line is disrupted between model changes.