Lead Times
Lead
times in Oracle are divided into several elements. The relationship between
these
elements and the various types.
Preprocessing
The time it takes to prepare an order for release;
this might
be the
time it takes to prepare a shop packet for manufacturing or to prepare
a
purchase order. This is sometimes referred to as paperwork lead time.
Fixed The portion of an item’s lead time that does not
vary with the order
quantity.
Setup time is a typical example; this is often a fixed amount of
time,
regardless of the size of the order. Planning uses fixed lead time to
plan both
manufacturing and purchase orders.
Variable
The portion of lead time that varies with the
order quantity.
Planning
uses variable lead time to plan manufacturing orders only.
Processing
The time it takes for a supplier to fulfill your
purchase order
once
released or the typical time it takes to complete a discrete job for the
item. For
manufactured items, this can be calculated from the fixed and
variable
lead times and represents the time it takes to manufacture the Lead
time lot
size quantity of the item; as such, it is an average. It is used to
calculate
the cumulative lead times. Planning does not use processing lead
time at
all for manufactured items; it uses the combined fixed and variable
lead
time. For purchased items, planning will use the processing lead time
only if
you do not specify a fixed lead time for the item.
Postprocessing
The time it takes to put away purchased material
after it is
received.
Planning uses this for purchased material only; for manufactured
items,
you should include this in your routings if it is significant.
You can
calculate fixed, variable, and processing lead times from your routing
time, as
described in Chapter 4. This process uses the lead time lot size, which you
also
specify on this tab.
The Lead
Times tab also includes two types of cumulative lead time:
Cumulative
Total The “critical path” lead time, or the time it
takes to
buy the
first piece of raw material, manufactures all the subassemblies
and makes
the item.
Cumulative
Manufacturing The cumulative lead time for manufacturing
activities
only; this is the cumulative total lead time, minus the purchasing
lead
time.
Cumulative
lead times can be used to set the different planning time fences or
the
Infinite Supply Horizon in Oracle Inventory ATP rules. Using a cumulative lead
time
instead of a user-defined number of days means that these fences and horizons
can
shrink as you reduce lead times, without additional maintenance. Cumulative
lead
times are also helpful in reviewing proposed engineering changes; if you
schedule
a change
inside an item’s cumulative lead time, you may require expediting of
material
to satisfy the new demand. You can calculate cumulative lead times with
the
Rollup Cumulative Lead Times concurrent program after you have calculated or
entered your item lead times.
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