SytelineMaster

The purpose of the Lead Time Processor (LTP) utility is to calculate an item’s fixed and variable lead times using the operations that make up its current routing. The fixed lead time is expressed in days. The variable in hours and is the run time for 1 piece.
Basic Algorithm
If you answer "No" to the "Use WC Calendar" and "Use Offset Hours" options, the LTP totals the run time for each operation in the routing and posts the result into the item master variable lead time field. If the work center is machine or machine and crew scheduled, the machine hours are accumulated. If it is purely crew scheduled, the labor hours are used.
If you leave the Shift ID blank it totals the move, queue, setup and finish hours for each operation, divides the total by the default shop calendar average hours per day and posts the resulting number of days into the item master fixed lead time field.  If you enter a Shift ID, the move, queue and finish hours are divided by the average number of hours per day from that shift rather than the default shop calendar.  The Shift ID field was added for the fix to APAR 107859 in the SQL versions (SL7 and higher).     
The variable time is adjusted by the operation efficiency (lead time / oper eff / 100) and work center utilization (lead time / wc util / 100).
If an operation has a value in the "Fixed Sched Hrs" field, that figure is added to the fixed lead in place of using the setup and run time.
Item master lead times are used by a number of functions in the system. One of the most important is the MRP module’s passing of planned orders from parent to component. The date assigned to the material requirement is calculated as:
PLN due date – (((PLN qty * var lead) / default shop cal hrs per day) + fixed lead)
The "Use WC Calendar" and "Use Offset Hrs" options exist so that the system’s lead time calculations will be more accurate if your are using operation overlapping and multiple shop calendars with varying hours per day. The following explains the how using those two options will affect the calculations.
Use WC Calendar
The "Use WC Calendars" option was designed to handle the situation where the various operations in an item’s routing use work centers that are tied to different shop calendars that have a varying number of hours per day. If you do not use this option, the LTP uses the hours per day from the default calendar when converting the fixed hours to days.
If some of the operations in the item’s standard routing had more (or less) hours per day than the default calendar, the date MRP arrives at when passing planned orders will often be different than the date at which scheduling would arrive since scheduling considers the extra (or less) time available in those work centers.
If you answer yes to the option, the LTP factors in the variable length calendars by calculating a "calendar factor" for each operation that does not use the default calendar. This factor is calculated as:
(avg hrs per day from default cal / avg hrs per day from oper’s calendar)
The resulting figure is then multiplied by the fixed and variable times for the operation in an attempt to compensate for the extra hours available per day. e.g. if an operation that uses a 10 hour/day work center has 1 hour per piece of run and the default calendar has 8 hours, there will per .8 hours added to the cumulative variable lead time for the item than 1.
Use Offset Hrs
The "Use Offset Hrs" option gives you the ability to factor the operation offset hours into the lead time calculations. If you answer "No" to the option, the LTP simply accumulates the setup and run for each operation as described above. This assumes each operation starts when the previous finishes and gives no consideration to operation overlapping which MAPICS handles with the Offset hours field.
When you answer "Yes" to "Use Offset Hrs", the algorithm changes dramatically in an attempt to compensate for the overlap. When the LTP encounters an operation with offset hours it will deduct the previous operation’s fixed and variable times from the running totals and add in the current operation’s offset to the fixed running total.
Basically, this means that the system will assume that the current operation’s offset is the duration of the previous operation. It will NOT change the actual values in the move, queue, setup and run hours fields of the previous operation.
For example, suppose you have an item with a typical lot size of 100 with 3 operations, each with 1 hour per piece of run time. Operations 20 and 30 have offset hours of 10 which means the begin 10 hours after the start of the previous operation.
If you elect not to have the LTP consider offset, it calculates fixed hours of 0 days and variable lead of 3 hours. When MRP passes a planned order for 100 it uses 300 hours (100 * 3 hr var lead) which comes to 38 days. When the planned order is turned into a job, the scheduling system would use the offset and arrive at 130 hours which is 16 days. The results in MRP showing the materials being needed 21 days earlier when the planned order is being passed then it will when the job is created.
Since operation 30 "covers" all but the non-overlapped time of operations 10 and 20, the offset hours from 20 can be considered a fixed duration for 10 and 30’s offset can be considered a fixed duration for 20.. Since offset does not vary with quantity, it makes sense to store this offset as fixed lead time.
In this example, if you tell the LTP to consider offset it would use operation 20’s offset of 20 hours as fixed time for 10 and ignore 10’s variable time. It would then use 30’s offset and use it for 20’s fixed and ignore 20’s variable. This would result in variable lead if 1 hour (30’s variable) and a fixed lead of 3 days (30 / 8 = 2.5 rounded to 3).
For a planned order for 100, MRP would pass the order using:
(100 pieces * 1 hr var lead) + 3 days fixed = 16 days
Using these two options, there may be a small difference between MRP’s calculation and scheduling’s calculation but it will certainly be more accurate than if not using them. It is important to realize that MRP is a planning tool, not a scheduling tool and cannot be expected to be as precise as the scheduling algorithm. To have MRP "schedule" each planned order using the item’s current routing would not be feasible purely from a processing time perspective.

Overview

There are four lead time fields in the Syteline item master: fixed, variable, paperwork and dock-to-stock. The fixed, paperwork and dock-to-stock leads are expressed in days and the variable is expressed in hours (run time per piece). For purchased items, they must be manually entered. For manufactured, they can be either manually entered or you can use the Lead Time Processor utility which populates the fixed and variable fields using the times in the item’s current routing .
In general, purchased and transferred items will have a fixed lead time and perhaps a paperwork and dock-to-stock but no variable. Manufactured items will typically have a fixed, variable and perhaps a paperwork but not a dock-to-stock. The following is an explanation of what functions in the system use lead times and how they are used. It is broken down by manufactured vs purchased items.
NOTE: All calculations of dates involving item master lead times are done using manufacturing days (M-days), not calendar days. For example, when the system deducts 10 days from an end date to arrive at a start date, it is actually counting back 10 M-days

Manufactured Items

The lead times for manufactured items are used to estimate job start dates and material requirement dates, which are essentially the same thing. That is, you need the material at the start of the job. The calculation used for manufactured items to arrive at a projected start date is the following. The .499 is added before the integer function (which rounds) is used so that it always rounds up to the next full day.
start date = end date – fixed lead – integer((var lead * qty / hrs per day) + .499)
The following functions use this calculation:
1) Job Creation
When you manually add a job, you must enter either the start or end date. Whichever you enter, the system arrives at the other using this calculation. When you use a system feature which creates a job, the end date defaults from the source record’s due date and the start is calculated using this formula.
Manually add a job
Firm a PLN to job from the MRP Detail Display
Firm MPS to job from the MPS screen
Add a production schedule release
X-ref and create a job from CO line item
X-ref and create an estimate job from an estimate line
X-ref and create job from a transfer order line item
X-ref and create job from project resource
2) MRP passing requirements
When a parent item has a PLN or and MPS receipt, the system passes it to the materials in the item’s current BOM to create PPLN and PMPS requirements for the materials. The date assigned to those requirements is calculated with the above formula using the MPS or PLN due date as the “end date”.
This calculation is also used to pass job requirements to the job’s BOM if the MRP parameter “Use Dynamic Lead Time” is No (or not checked). In that case, the item master lead times are deducted via the formula from the job’s “MRP End” date.
3) MRP Order Action report
The order action report reads through all planned orders and prints those that need to be released. The report deducts the item’s lead time from the planned order due date using the following calculation which differs from the one given above in that paperwork lead and dock-to-stock are both also deducted. The report prints the PLN if the resulting “Release Date” is less than the “Ending Date” entered on the option screen. The paperwork lead is included since that is time before the start of the job which must be accounted for when releasing planned orders. The dock-to-stock is included since the report uses the same calculation for purchased and manufactured items but while have no impact since it should be zero for manufactured items.
release date = PLN due date – fixed lead –
integer((var lead * PLN qty / avg hrs per day) + .499) –
dock-to-stock lead – paperwork lead.

Purchased Items

For purchased items, the lead times are used to either calculate a PO release date when starting from a due date or to calculate a PO due date when starting with release date. The specific functions which use lead times for purchased items in one way or another are the following:
1) MRP Order Action report to calculate Release Date
Used as described above for manufactured items. The variable lead is used in the calculation but will typically be zero for purchased items.
2) Firming a PLN from MRP
When you firm a planned order from the MRP detail display, the system deducts the item’s dock-to-stock lead time from the PLN due date to arrive at the PO line (or PO requisition line) due date. The PLN due date is the date you need to issue the material to the job so the dock-to-stock must be deducted from that date for the PO due date.
3) X-ref and create PO from a job material
Same logic as item 2 applies here. The dock-to-stock is deducted from the operation’s start date if not blank or the job’s start date if the operation’s is blank.
4) “Matl Chk FWD Sched” algorithm
Enabling the “Matl Chk FWD Sched” SFC parameter causes the scheduling routine to potentially move out the start date of operations if it determines that purchased, non-stocked materials cannot be available by the desired start date. If the material is not tied to a PO line item, determines when it can be available by adding the item’s lead times to the current date. (i.e. when can we have the material if ordered today?). If an item/vendor cross reference records exists for the item, the system uses the lead time from the number one ranked vendor. Otherwise, it uses item master lead times.
5) Calculating a “Release Date” displayed on reports
A handful of purchasing reports deduct the item’s fixed and paperwork lead times from the PO line due date and print the result in a “Release Date” column. The dock-to-stock is not deducted since it is assumed that it was already deducted from the true need date when arriving at the PO line due date. The reports which show this are the following:
PO Status
Purchase Requirements (if status is planned)
PO Requisition by Buyer
6) Calculating due date when manually adding PO
If you manually add a PO (or requisition) line and an item/vendor cross reference record exists for the item and the PO vendor, the default due date is calculated by adding the item vendor record’s lead time to the date listed below:
Regular PO line: adds item vendor lead to PO order date
Blanket PO release: adds item vendor lead to Rel Date entered
PO requisition: adds item vendor lead to Req Date
NOTE: Unlike the item master lead time field, the item vendor cross reference lead time should be expressed in calendar days, not manufacturing days. When used as described in this point and point 4 above, the item vendor lead is simply added to the one date to arrive at the other. That is, it does not count M-days as do the functions which utilize the item master lead times.
Transferred Items
For the item with a source of Transferred, the fixed and variable lead time fields are not used by the cross-site functionality. When the MRP module passes planned orders (PLNs) for a transferred item to the item’s supply site to become a TPLN requirement in that site, date assigned to that requirement is the due date of the PLN minus the Transit Time in the Inter-Site Parameter record. Also, when you firm the PLN into a transfer order the Transit time is also used for setting the line’s Schd Ship Date. The Schd Rcvd Date is set to the PLN’s due date and the Transit Time is deducted from the date to arrive at the Schd Ship Date.
However, the Order Action report does use the item master lead time to calculate the Release Date for PLNs. That release date is then used to determine if the PLN will display in the “Transfer Orders to be Firmed” section of the report. For that reason, it may be best to set the item master fixed lead time equal to the transit time from the item’s ship site for all transferred items.