Defining Lead Time for APS Planning

In certain planning situations, the system may use lead time to approximate the time needed to acquire, make, or receive an item. In all cases, lead time is defined in the following fields on the Items form:

Fixed Lead Time
Variable Lead Time
Expedited Fixed Lead Time
Expedited Variable Lead Time
Paper Work Lead Time
Dock-to-Stock Lead Time

Note: Paper Work Lead Time and Dock-to-Stock Lead Time are also used by the MPS Processor, Material Planner Workbench Generation, and on the Order Action Report.

This topic describes how lead time applies to purchased items, manufactured items, and transferred items. It also describes how to use the Expedited Lead Time functionality.

Where Purchased Item Lead Time is Used

For purchased items, you must enter the lead time values manually in the lead time fields. The system uses purchased item lead time to perform the following functions:

To calculate the release date of a purchase order when you firm a planned order. The system deducts the item's dock-to-stock lead time from the operation's start date, if not blank, or the job's start date if the operation's start date is blank.
When you cross-reference and create a purchase order from a job material. The system deducts the item's dock-to-stock lead time from the operation's start date, if not blank, or the job's start date if the operation's start date is blank.
When you manually create a purchase order line or purchase order requisition line and an item/vendor cross reference record exists for the item and the PO vendor. The system calculates the default due date by adding the item vendor record's lead time to the appropriate date. A PO line adds item vendor lead time to PO order date. A blanket PO release adds item vendor lead time to the release date you entered. A PO requisition line adds item vendor lead time to the requisition date.
To calculate the due date of safety stock planned orders (current date/time + lead time).

Where Manufactured Item Lead Time is Used

For manufactured items, you can enter the lead times manually or use the Lead Time Processor to generate the lead times from the current routing's operation times. The system uses lead time to plan manufactured items in these situations.

To plan the start date of a job when any of these conditions are true: the item has no routing, and the MRP Item field is selected for the item on the Items form.
To calculate the due date of safety stock planned orders (current date/time + lead time).
To determine which routing and BOM to use when planning a requirement for an item. The system decides which routings and BOMs to use through the indented bill of manufacturing by using lead time to estimate when they will be used, and then comparing those times to the effective dates for the possible routings and BOMs.

Note: For manufactured items that are not specified as MRP Items, lead time is not used when the system passes parent item requirements down to components. Component due dates are based on the start date of the operation where the component is used (or the start date of the job, depending on the setting of the Plan Materials at Operation Start planning parameter.

Where Transferred Item Lead Time is Used

The system uses lead time to plan transfer orders if:

You are running APS Planning (in single-site mode) and the demand is for an item with a remote Supply Site. Planned transfer demand is replicated to the Supply Site. See “Setting Up Planned Transfer Order Replication” for more information.
You are running APS Planning (in global mode), the demand is for an item with a remote Supply Site, and the system cannot contact the remote site to plan the transfer order. The transfer supply is planned at the local site using lead time.

The system calculates lead time for transferred items in the same manner as purchased and manufactured items, except it adds the transit time (defined on Inter-Site Parameters) to the total lead time. For example, if an item's lead time from the FLT + (VLT * Qty) calculation is 1 day, and it takes 3 days to ship to the receiving site, the total lead time is 4 days.

Release Date Calculation

APS uses this formula to calculate the planned order release date:

Start/Release Date = PLN Due Date - (FLT + DSLT + PWLT + (VLT * Quantity Required)), where FLT = Fixed Lead Time, VLT = Variable (per-piece) Lead Time, DSLT = Dock-to-Stock Lead Time, and PWLT = Paperwork Lead Time

EXAMPLE: For this example purchase order, assume the following conditions:

Current date/time = 5/16/2002 (Thursday) at 08:00
Planned purchase order due date = 5/30/2002 at 08:00
Quantity = 10

Purchased item's lead times are:

FLT = 1 day
VLT = 0.5 hour (although purchased items usually have a VLT of 0, a non-zero value is used here for illustration purposes)
DSLT = 1 day
PWLT = 0.5 day

The system calculates the release date of the purchase order by performing this calculation:

Sums the FLT, DSLT, and PWLT lead time values for a result of 2.5 days
Multiplies the VLT value of 0.5 by the quantity of 10 for a result of 5 hours
Adds 5 hours to (2.5 days * 24 hours) for a result of 65 hours total lead time
Starting at the due date (5/30/2002 at 08:00), the system counts backward 65 hours. By default, it accumulates lead time 24 hours per day, 7 days per week
The resulting release date is 5/27/2002 at 14:00

Hours vs. Days

The lead time values expressed in days on system forms are converted to hours during these calculations.

24-hour Calendar

For all calculations involving lead time, the system assumes a 24-hour day X 7-day week by default. If you are using APS, you can configure it to use a defined range of business days by creating a shift named “PCAL” on the Scheduling Shifts form.

Using Expedited Lead Times

For special cases where you need to reduce the normal lead time, you can use the expedited lead time features. APS uses expedited lead time when the initial pull planning using standard lead time projects a date in the past. You can apply lead time reduction for specific items or apply it to all items.

Note: When you use mass cross-referencing through the Material Planner Workbench Generation form, expedited lead time is not used.

The Use Expedited Lead Time parameter on the Planning Parameters form enables or disables the application of expedited lead times at the item level and global lead time reduction. You can enable or disable expedited lead time usage for runs of APS Planning (select For Planning) and/or for Get ATP/CTP operations (select For ATP/CTP).

Expedited Lead Time for Specific Items

If you specify a value for the Expedited Fixed Lead Time or Expedited Variable Lead Time values on an item, the lead time calculations use the expedited values INSTEAD of the item's normal Fixed Lead Time and Variable Lead Time values. For example, if Expedited Fixed Lead Time contains a value, the lead time calculation is:

Start/Release Date = Due Date - EFLT + (VLT * Quantity)

Global Lead Time Reduction

You can also reduce lead time for all items using the Fixed and Variable Lead Time Reduction (see “Items - Fixed Lead Time” and “Items - Variable Lead Time” for more information) parameters on the Planning Parameters form. These options reduce the standard fixed and/or variable lead time by the specified value for all items.

During planning, the system calculates the total lead time with this formula: Start/Release Date = Due Date - (FLT - FLTR) + ([VLT - VLTR] * Quantity), where:

EFLT = Expedited Fixed Lead Time
FLTR = Fixed Lead Time Reduction
EFLT = Expedited Variable (per-piece) Lead Time
VLTR = Variable Lead Time Reduction

Depending on the combination of selected options and values, there may be other combinations of the lead time formula, such as:

Start/Release Date = Due Date - (FLT - FLTR) + (VLTR * Quantity)
Start/Release Date = Due Date - EFLT + ([VLT - VLTR] * Quantity)

Notice that the Fixed/Variable Lead Time Reduction values reduce the standard lead times, while the Expedited Fixed/Variable Lead Time values specified on the Items form actually replace the standard lead times.

Indication of Expedited Lead Time on Output Forms and Reports

On the Purchase Order Lines, Purchase Order Blanket Releases, and Purchase Order Requisitions Lines forms, the Expedited field indicates when the system used expedited lead time to plan a line item.

On the Purchase Order Report, Change Order Report, PO Requisition Report, and the Change Order Detail Report, a note indicates when the system used expedited lead time to plan a line item.

On the Planning Detail form, Exceptions Report, or Material Planner Workbench form, the "Used Expedited Lead Time" exception message appears for a supply record if the system used expedited lead time to allocate that supply to a demand.

Handling Temporary Vendor Lead Time Problems

Your vendors may have temporary problems meeting their lead times for certain items. To ensure that APS creates the planned order for a purchased item with the appropriate lead time in this situation, enter the Earliest Planned Purchase Receipt date on the Items form.

This date temporarily overrides the item's standard and expedited lead times. When APS creates a planned order for this item, it determines that the item can be received either by the current date + lead time or by this Earliest Planned Purchase Receipt (see “Items - Earliest Planned Purchase Receipt” for more information) date, whichever is later.