Lead Time Offsetting Computations
Bills of Material lets you automatically compute item, bill of material and routing information required for dynamic lead time offsetting. You can also maintain lead time information manually.
Manufactured Items
Dynamic lead time offsetting uses the following lead time attributes for discretely manufactured items:
- fixed lead time
- variable lead time
- preprocessing lead time
Dynamic lead time offsetting uses the following lead time attributes for repetitively manufactured items:
- processing lead time
- fixed lead time
Purchased Items
Dynamic lead time offsetting uses the following lead time attributes:
- preprocessing time
- processing lead time
- post-processing lead time
Routings
When computing manufacturing lead times, operation and resource offsets are automatically assigned to a routing. For material and resource requirement planning, you can optionally include offsets when computing requirement dates.
Dynamic lead time offsetting offsets dates in two steps, computing total lead time and offsetting the date by total lead time. Total lead time contains both fixed lead time and the quantity-dependent portion of lead time. Preprocessing lead time is also included for discrete items.
To compute the total lead time for discrete items use the following equation:
preprocessing lead time + fixed lead time +(order quantity x variable lead time)
Compute the total lead time for repetitive items using the following equation:
fixed lead time + (daily rate x processing lead time)
Offset the date by total lead time using the following equation:
start date = requirement date - total lead time
Master Scheduling/MRP uses dynamic lead time offsetting to compute a planned order release date. Master Scheduling/MRP computes total lead time and then uses the workday calendar to calculate the planned order release date.
Suppose your MRP plan produced a requirement for 100 discretely manufactured assemblies on March 12 and the following information exists for that assembly:
• Requirement date = 12-MAR
• Fixed lead time = 2 days
• Variable lead time = .05 days (1 day per 20 units)
• Preprocessing lead time = 0 days
• Order quantity = 100
Master Scheduling/MRP first computes the total lead time as follows:
Total lead time = 0 + 2 + (100 x .05) Total lead time = 7 days
Suppose your organization's workday calendar has a workday pattern with five days on and two days off. Workdays 1 - 5 are March 1 - 5. Saturday and Sunday, March 6 and 7, are off. Workdays 6 - 10 are March 8 - 12. Master Scheduling/MRP then calculates the planned order release date as follows:
Start date = requirement date - total lead time Start date = (12-MAR) - 7 days Convert planned order requirement date to a workday (using your organization's workday calendar).
Start date = Date ((Workday 10) - 7)) Start date = Date (3)
Finally, determine the start date.
Start date = 03 - MAR (planned order release date)
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