Lead Time Calculation

BOM Lead Time Calculation

Field Description

Start Processing

Select this to commence processing.


	Structure on/off dates are ignored Statistical parts and its lead time is not carried through to its parent. The dock-to-stock of a part is not included in its lead time, but is incorporated into the lead time of that part's parent. If a component is offset by an operation that does not exist, then the program assumes the component is required at the beginning of the manufacturing process. The calculation assumes that: you have infinite capacity (i.e. capacity to start operations is always available on the working days defined against your calendar) none of the components required are in stock

The manufacturing lead time (MLT) for a subcontract operation is calculated as:

MLT = LT + (DTS + OFF) * NWR)

where LT = lead time against the subcontract operation (i.e. the purchasing lead time). Note that this lead time is in absolute days and the non-working days ratio is therefore not applied to it.

DTS = the dock to stock against the subcontract operation

OFF = the offsite time against the subcontract operation

MOVE = movement time (only include if not negative)

NWR = non-working days ratio (calculated as: DAYS IN YEAR / (DAYS IN YEAR - NON-WORKING DAYS) as per your calendar (Company Calendar).

When processing co-products, if the co-product type is defined as concurrent (BOM Co-Product Maintenance) then all co-products inherit the same lead times (i.e. lead and manufacturing lead times).

For all co-products that are not Sequential, their lead time and the MLT (Manufacturing Lead Time) are set to the same as those for the notional part itself (including the dock to stock of the notional part, as it is assumed that the notional part's dock to stock is the same as its co-products' dock to stock).

If the co-product type is sequential, then the manufacturing lead time is calculated for the co-product up until the time it is completed. In addition, for sequential co-products, the overall lead time (lead time including purchasing and subcontract) is only calculated for materials attached to the co-product up to the time the item is completed.

For sequential co-products, the MLT (Manufacturing Lead Time) for all subsequent operations is subtracted from the Notional part's MLT/Lead time to obtain the co-products' lead time. If a co-product is attached multiple times to different operations, then the lowest operation's lead time and MLT is used.

Print Select this to print the information currently displayed in the Report pane.

Save Form Values

This option is only enabled in Design mode (Automation Design). Your selections are saved and applied when the program is run in automated mode.

Form values and defaults are applied at operator level. They are not saved at role or group level.

Information

Field	Description
Lead time calculation
Re-calculate dynamic elapsed times	Select this to re-calculate dynamic elapsed times for operations defined as dynamic. The program uses the current dynamic elapsed times to calculate the lead time and manufacturing lead time if this option is not enabled.
After processing completed	These options are displayed within programs that can be automated. They enable you to indicate the action you want to perform once processing is complete (see Automation Design).

Field

Description

Lead time calculation

Re-calculate dynamic elapsed times

Select this to re-calculate dynamic elapsed times for operations defined as dynamic.

The program uses the current dynamic elapsed times to calculate the lead time and manufacturing lead time if this option is not enabled.

After processing completed

These options are displayed within programs that can be automated. They enable you to indicate the action you want to perform once processing is complete (see Automation Design).

Report

The information in this pane is displayed once the calculation is complete, providing you did not select the option: After processing completed > Close this application.

This displays the log report resulting from the calculation.

The report includes the following information:

whether the calculation was successfully completed
whether structures exists with more than 15 levels
whether a looping structure exists (parent parts are repeated as components in the same structure)
the start and end times of processing


	You use the After processing completed options to print or email this information.

Calculation routine

The lead time calculation program performs the following routine:

Clearing of the current lead times

The manufacturing lead time field is cleared. The total lead time field is cleared if either components or operations are attached to the item.

Calculation of the longest lead times

The program scans the structure file - lowest level first - accumulating the lead times for each level and carrying the longest lead times through to the next level until the highest level is reached.

Raw materials (i.e. bought-out items) are deemed to have a manually entered lead time which is the time from the date that the purchase order is placed until the material arrives.

Sub-assemblies have a lead time which is the time of the longest components' lead time plus the total operation time (elapsed time + move + queue).

The longest lead time will take into account the fact that a particular component may be required some time into the manufacturing process. This could be defined as a number of offset days or a particular operation number.


	If a component is offset by an operation that does not exist, then the program assumes that the component is required at the beginning of the manufacturing process.

The Lead time (days) field against the parent item (Stock Codes) is updated with the manufacturing lead time calculated.

Calculation Examples

In all the following examples, the calendar (Company Calendar) is defined as: all Saturdays and all Sundays are non-working days. All other days are working days.

The NWR (non-working day ratio) is therefore: 365/(365 less (52 Saturdays + 52 Sundays)) = 365/261 = 1.398467(rounded)

In addition, the following acronyms are used:

Acronym	Description
OP No	Operation Number
LT	Lead Time
OFF	Offsite Time
DTS	Dock to Stock Time
MOVE	Move Time
RUN	Run Time
QUE	Queue time
MLT	Manufacturing Lead Time

Example 1

The BOM for made-in item PSUB consists only of a sub-contract operation SUB

The following applies:

Item	OP No	LT	OFF	DTS	MOVE	RUN	QUE	MLT (calculated)
PSUB				1				28
SUB		5	2	3	4			27

The MLT for SUB = LT + OFF + DTS + MOVE + ((OFF + DTS + MOVE) * NWR) = 5 + 2 + 3 + 4 + (9 * 1.398467) = (14 + 13)= 27

Note: (9 * 1.398467) = 12.586203 (rounded) so this equates to 13 days (rounded up).

The MLT for PSUB = (DTS of PSUB + MLT of SUB) = 1 + 17 = 18

Example 2

The BOM for made-in item POP consists only of an internal operation INTOP

The following applies:

Item	OP No	LT	OFF	DTS	MOVE	RUN	QUE	MLT (calculated)
POP				1				3
INTOP	1					5 (hours)	1 (day)	2

For simplicity, only a run time is defined against the internal operation.

In addition, the following productive units are defined for work center INTOP: Number of units =1, Time per unit/day = 8.00, Normal capacity per unit/day = 8.00; utilization percentage = 100.

The MLT for INTOP = Elapsed time + queue time = 1 + 1 = 2

Elapsed time calculation for an internal operation can be viewed using the Structures and Routings program.

The MLT for POP = MLT for INTOP + DTS of POP = 2 + 1 = 3

Example 3

The BOM for made-in item PSUBOP consists of an Internal operation INTOP and a sub-contract operation SUB:

The following applies:

Item	OP No	LT	OFF	DTS	MOVE	RUN	QUE	MLT (calculated)
PSUBOP				1				28
INTOP	1					5 (hours)	1 (day)	2
SUB	2	5	2	3	4			27

For simplicity, only a run time is defined against the internal operation.

In addition, the following productive units are defined for work center INTOP: Number of units =1, Time per unit/day = 8.00, Normal capacity per unit/day = 8.00; utilization percentage = 100.

The MLT for INTOP = Elapsed time + queue time = 1 + 1 = 2

Capacity calculations can be viewed using the Structures and Routings program.

The MLT for SUB = LT + OFF + DTS + MOVE + ((OFF + DTS + MOVE) * NWR) = 5 + 2 + 3 + 4 + (9 * 1.398467) = (14 + 13) = 27

The MLT for PSUBOP =(DTS of PSUBOP + MLT of SUB) = 1 + 27 = 28

The MLT of SUB is used as it has a longer lead time than INTOP in this example.

Notes and warnings

Prerequisites

You should run the Structure Validation program before using the Lead Time Calculation program. The reason is that the calculation aborts if any errors are encountered (e.g. structures with more than 15 levels and parent parts that are repeated as components in the same structure).
Ensure that working and non-working days in your company calendar are correctly defined (Company Calendar) because the lead time varies according to the number of non-working days defined.

Bought-out at warehouse level considerations

Component lead times are used to calculate the lead time of the parent. If the component is defined as bought-out at warehouse level (Inventory Warehouse Maintenance for Stock Code) then the lead time value of components defined against the warehouse is used instead of the values held against the stock code.

eSignature considerations

Electronic Signatures provide security access, transaction logging and event triggering. This enables you to increase control over your system changes.

Access to the following eSignature transactions within this program can be restricted at Operator, Group, Role or Company level. You configure this using the eSignature Setup program.

eSignature Transaction	Description
BOM Lead time calculation	Controls access to the Start Processing function in the Lead Time Calculation program.

Hints and tips

Record amendments

Amendment journals are created if these are required for Inventory (Inventory Setup).