Variable Lead Time
If an item on the work order has a variable lead time, the system determines the start date by using the lead time per unit to backschedule. The system uses this calculation:
[((Leadtime per unit × order quantity) / Time basis code unit value) + Setup + Total queue] / Work hours per day
For example, assume:
Work order due date = October 15.
Lead time per unit = 32 hours.
Work order quantity = 1000.
Setup = 1 hour.
Queue (including move time) = 9 hours.
Time basis code = 10,000 (code 4, which indicates 10,000 units).
This information is from the Item Branch File table (F4102).
Work hours per day = 8.
[((32 hours × 1000) / 10000) +1 hour + 9 hours] / 8 hours = 1.65 days
The system calculates the start date by counting back two working days on the shop floor calendar from the due date. The work order start date is October 13.