Monday, February 2, 2015

Lead times


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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