BOM: metalink上Lead time相关知识ZT(一)

Oracle Manufacturing lead times Calculation and Setup

This document serves as a guide to Oracle Manufacturing Lead times. It answers the following questions:
1. How are lead times, in Oracle manufacturing applications, used?
2. How are lead times maintained?
3. How do lead times impact other processes?
4. How are lead times defined?
This document contains numerous facts and information on lead times used in　Oracle Manufacturing Applications and is intended for anyone having a need to setup or understand the functionality of Oracle Manufacturing Lead times

 

1. BASIC MAINTENANCE.
a. The workday calendar must be setup correctly and rebuilt any time
modifications are made to the calendar.
Navigation paths: Bill of Materials/Setup/Calendars
Inventory/Setup/Organization/Calendars
b. Once modifications are made, rebuild the calendar by selecting the
special option on the top tool bar. On the drop down list, click on build.
c. Any time changes are made to a routing or resource, recalculate and
rollup the lead times.
Navigation path: Bill of Materials/Routings/Lead times
2. GENERAL FACTS
a. For an item to have manufacturing lead times calculated, it must be a
make item. Lead times are not calculated for purchased items even if they
have a routing.
1) Navigation path: Inventory/Items/Organization Items.
2) Select the General Planning alternate region.
3) Choose the make option for make or buy.
b. Set the scheduling option for the operation resources to yes.
1) Navigation path: Bill of Materials/Routings.
2) Put the cursor on the desired operation sequence.
3) Click on the [Operation Resources] button.
4) Select the desired resource sequence with your cursor.
5) Select the Scheduling alternate region.
6) Select the Yes option for schedule.
c. If using a fixed lead time for a resource, use a basis of Lot.
1) Navigation path: Bill of Materials/Routings.
2) Put the cursor on the desired operation sequence.
3) Click on the [Operation Resources] button.
4) Select the desired resource sequence with your cursor.
5) Select the Main alternate region.
6) Select the lot option for the basis.
d. If using want a variable lead time for a resource, use a basis of Item.
1) Navigation path: Bill of Materials/Routings.
2) Put the cursor on the desired operation sequence.
3) Click on the [Operation Resources] button.
4) Select the desired resource sequence with your cursor.
5) Select the Main alternate region.
6) Select the item option for the basis.
e. If a number other than 1 (the default) is entered in the assigned units
field, the scheduler will divide the lead time for that resource by the number of assigned units for the resource entered and use the fractional lead time in the lead time roll up. The assigned units field tells the scheduler how many resources/machines are available to the job in order to complete it in less time. In other words, if a 2 is entered, the lead time for this resource will be cut in half. If you a 3 is entered, the lead time will be one third and so on.
1) Navigation path: Bill of Materials/Routings.
2) Put the cursor on the desired operation sequence.
3) Click on the [Operation Resources] button.
4) Select the desired resource sequence with your cursor.
5) Select the Scheduling alternate region. Here you can change the
number of assigned resources that you want for this resource.
f. MRP expects that material due is received into inventory by the beginning of the business day on which it is due. Consider receiving it into inventory at the close of business on the previous day. Simply change your receiving function to accommodate this.
g. MRP will use the fixed lead time if entered. This can be manually
entered into the organization item form. in inventory.
Navigation path: Inventory/Items/Organization Items
h. Fixed lead time is automatically entered if the Lead time Rollup is done. If the fixed lead time is manually entered, it will be over-written whenever a lead time rollup is done.
i. When doing a lead time rollup, there is no validation for items if a range of items is selected. If a specific item is selected, it validates that item and, if it does not have a bill, it does not calculate any lead times.j. To set up a variable lead time for a resource that can complete one unit every ten minutes:
1) Navigate to Bill of Materials/Routings/Routings.
2) Query up a routing.
3) Put the cursor on the desired operation.
4) Click on the [Operation Resources] button.
5) Enter the resource sequence and the name of the resource that will do the work.
6) Make sure the Unit of Measure (UOM) that defaults is correct. In almost all cases it should be hour (HR).
7) Select Item from the drop down menu for basis.
8) Enter six (6) in the Inverse column under rate or amount. The system has now been told that six items per hour or one unit every ten minutes
can be completed.
k. Oracle WIP uses WIP Detailed Scheduling and Repetitive Line Scheduling to determine order start date. Therefore, it is conceivable that MRP and WIP could recommend different starting dates to meet the same requirement due to the more refined method of order start date calculations in WIP.
l. Oracle starts calculating the lead time at 12:00AM or the start time of the first defined shift for the day.

m. Oracle always counts idle time in the variable lead time calculations because it uses a 24 hour day. Therefore, the lead time is expressed as a decimal value of the 24 hour day. Calculations are based upon the second.
n. Any time-based resource will be converted and rounded to the number of seconds. The converted value has to be at least one second in order to be calculated. The rounding to number of seconds is by design. For
non-time-based resources, the conversion rate is zero and will not have
any effect on lead time calculations. For example, WIP (the application
which actually does the calculation), converts a usage rate of .000018 of
an hour to .0648 seconds (.000018 x 3600 second in an hour) which is then rounded to 0. The code will not work if the precision is below a second. This is standard functionality.

o. When doing forward scheduling, you have to schedule the resource
based on the shift hours (using start and stop times), workdays and non-workdays, the start date and time of the lot and the usage rate of the
resource. In doing this, any elapsed or idle time, due to a resource not
being available to work, will be added to the lead time. Depending on the
size of the lot being processed, you could have a wide variety of
completion dates and times. For example:
- You have a resource that can process one unit per hour and is
available from 8:00 to 4:00.
- A lot of three units will be moved to the next resource at 11:00.
The lead time for this lot is .125 days for this resource.
- A lot of 10 cannot be moved to the next resource until 10:00 the next day. This lot will then have a lead time of 1.0833 days for this resource.
p. Dynamic Lead time Offsetting is the estimation of the start date of an
order, operation or a resource, based on the order quantity, lead times and
the workday calendar. Depending upon the number of units, volume and usage rate, the lead time could be rounded to zero.
q. Detailed Lead time Scheduling calculates jobs to the second based on resource units available and the usage rates.
r. Using a lead time lot size greater than one will give a more accurate variable lead time. It should reflect the average lot size that will be
processed.
s. The Available 24 Hours checkbox on the resource schedule will ignore
manufacturing calendar days off if checked.
1) Navigation path: Bill of Materials/Routings.
2) Put the cursor on the desired operation sequence.
3) Click on the [Operation Sequence] button.
4) Select the desired resource sequence with your cursor.
5) Select the Scheduling alternate region.
t. Repetitive Line Lead times include:
1) Fixed line or routing based lead times.
2) Processing lead time.
u. Calculating the Lead time of Purchased Items.
1) The workday calendar is not included when calculating any lead times for purchased items. It is assumed that the supplier is a 24x7 operation in Releases 10.7 and 11.x.
2) The purchased items lead time is calculated as follows:
Postprocessing Lead time (time needed to move from receiving
to inventory) +Processing Lead time (time vendor needs the order before
delivery to your dock)
+Preprocessing Lead time (purchase order preparation)
3) The results are:
The dock date (found on the Planning Detail Report) is the date
by which the vendor should deliver the material to your dock.
Dock Date = Order Due Date - Postprocessing Lead time
The start date is the date by which the sales order should be given to the vendor.
Start Date = Dock Date - Processing Lead time
The order date is the date by which the purchase order should be started.
Order Date = Start Date - Preprocessing Lead time
4) You can assign values for fixed lead time instead of assigning
the processing lead time.
v. Calculating the Lead time of Manufactured Items:
1) Fixed Lead time (time your shop floor needs to manufacture the
item or complete the job).
Fixed lead time = lot time (usage rate or amount) / assigned units
2) Variable Lead time (time your shop floor needs to manufacture
each item - each piece * variable lead time)
Variable lead time =
total lot time + ((item based time * lot size) assigned units)
3) The planned order order date is the date by which you need to
start the process of creating a discrete job or repetitive line.
It is calculated as follows:
Planned order order date =planned order order date - preprocessing lead time
4) The planned order due date is the date by which the item is needed.
It is similar to the dock date for a purchased item.
5) The planned order start date is the date by which you need to
release a discrete job or start a line. It is calculated as follows:
Planned order start date = planned order due date - lead time offset
The lead time offset is used as follows:
Planned order due date - lead time ffset = planned order order date
The lead time offset is calculated as follows:
Lead time ffset = Fixed Lead time + (Variable Lead time * Order Quantity)
3. MANUFACTURING LEADTIME CALCULATIONS.
a. For items that you plan and cost with the same lot size, you specify
a value only for the standard lot size.
b. For items that you plan with one lot size and cost with a different lot
size, you can specify a value for the lead time lot size. BOM then
calculates the manufacturing lead time for the item using this value as
opposed to the standard lot size.
c. If one item's routing references a common routing, set either the lead-
time lot size or standard lot size to the same value.
d. Primary routings are automatically updated with the lead times.
e. Offset percent is calculated for each resource on a routing operation
as the percent of processing lead time required from previous operations.
This is calculated from the start of the job to the start time of a resource
at an operation.
f. A value of zero is assigned to the fixed, variable and processing lead-
time of a manufactured item that does not have a routing and is not
assigned to a repetitive line.
g. Detailed scheduling is used to compute the fixed and variable lead-
times. BOM does not consider pre-processing when computing manufacturing lead time.
4. CUMULATIVE MANUFACTURING LEADTIME CALCULATIONS.
a. BOM computes cumulative manufacturing lead times and cumulative lead- time by stepping through the indented bill structure.
b. BOM sets an item's cumulative manufacturing lead time using the
following:
1) Manufacturing lead time for the item. +
2) Maximum [(cumulative mfg lead time - offset days) for any
component in bill]
5. CUMULATIVE TOTAL LEADTIME CALCULATIONS.
a. BOM computes cumulative manufacturing lead times and cumulative lead- time by stepping through the indented bill structure.
b. BOM sets an item's cumulative total lead time using the following:
1) Total lead time for the item. +
2) Maximum [(cumulative total lead time - offset days) for any
component in bill]
6. ASSIGNING LEADTIMES.
Item Manufactured Purchased Attribute Item Item
------------------------ ------------ ---------
Pre-processing Lead time You enter You enter
Processing Lead time BOM/ENG You enter
Post-processing Lead time N/A You enter
Cumulative Mfg Lead time BOM/ENG N/A
Cumulative Total Lead time BOM/ENG N/A
Lead time Lot Size You enter N/A
7. HOW TO ...?
a. In order to set up a fixed lead time for a resource that takes one hour to complete:
1) Navigate to Bill of Materials/Routings/Routings.
2) Query up a routing.
3) Put your cursor on the desired operation.
4) Click on the operation resources button.
5) Enter the resource sequence and the name of the resource that will
do the work.
6) Make sure the Unit of Measure (UOM) that defaults is correct. In almost all cases, it should be hour (HR).
7) Select Lot from the drop down menu for Basis.
8) Enter one (1) in the Inverse column under rate or amount. You have now told the system that you can do one lot per hour.
b. In the Operation Resource form, in the Scheduling alternate region,
is a column called Offset Percent. This is the calculated percent of the
total manufacturing lead time that is completed by all of the previous
operations. For example, if all of the operations in the routing takes a
total of ten hours to complete, and the offset percent of a resource is 40%,
then this resource is started 4 hours after the start of the first operation.
c. It should be noted that when the calculate lead time program is run, it
will use the BOM revision that you have entered for the routing you have
selected to calculate the lead time. Lead times are connected to the
routing and not to the bill of materials. When you run the lead time roll
up, it will use the revision of the bill of material that you have selected.
This is because the lead time roll up program uses the lead times of
subassemblies for which the lead time has been previously calculated.
8. GLOSSARY OF LEADTIME DEFINITIONS.
a. FIXED LEADTIME is the portion of lead time that is independent of
order quantity. This could be setups, teardown, batch processes or
anything else that requires time to do a lot. Fixed lead times for an item
can be entered manually.
1) Navigation path: Inventory/Items/Organization Items.
2) Select the Lead time alternate region for the item.
3) Enter the desired Fixed Lead time and save the form.
Please note that a manually entered lead time will be replaced by the
lead times generated by the Manufacturing Lead time rollup.
b. VARIABLE LEADTIME is the portion of lead time that is dependent upon order quantity. It is the required time to produce one additional unit of an assembly. The formula the system uses is:
[(End date - system date) - fixed lead time] + lead time lot size.
Variable lead times for an item can be entered manually.
1) Navigation path: Inventory/Items/Organization Items.
2) Select the Lead time alternate region for the item.
3) Enter the desired Variable Lead time and save the form.
Please note that a manually entered lead time will be replaced by the lead-times generated by the Manufacturing Lead time rollup. The variable lead-time is used in dynamic lead time offsets.
c. PRE-PROCESSING LEADTIME is the time required to release a purchase order. It is used for Purchase orders, discrete jobs and repetitive lines. It can include the requisition processing and any approval cycles
required. It can also be used for the time necessary to create internal
paperwork for a discrete job or repetitive line from the time you learn of
the requirement.
d. PROCESSING LEADTIME is the time required to purchase or manufacture an item. It is computed as the time required to complete 1 lead time lot size of an item. The formula for this includes the fixed and variable portions of lead times. end date (for job 2) - system date
BOM determines an item's lead time lot size from two item master fields:
Standard Lot Size and Lead time Lot Size.
e. POST-PROCESSING LEADTIME is the time it takes to receive, inspect and move a buy part to inventory. You must physically enter
post-processing lead time for each purchased item.
f. CUMULATIVE MANUFACTURING LEADTIME is the time required to make anassembly if all raw materials are in stock. This assumes that you must manufacture every assembly, level by level. BOM automatically calculates this value.
g. CUMULATIVE TOTAL LEADTIME is the time required to make an assembly if no raw materials are in stock. This assumes that every raw material would either have to be ordered or manufactured. BOM automatically calculates this value.
h. TOTAL LEADTIME is the Fixed Lead time + (Variable Lead time * Order Quantity)..

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