Planning Periods

Depending on the conversation, Master Scheduling provides either three or four planning period options for reporting, entering data, and processing:

·     Calendar Weeks.  The beginning date of each week, taken from the Shop Calendar File, is used as the beginning of each period.  The day of the week that is considered to be the start date is specified by the user on the Master Scheduling system defaults record (Reference File category 464).

·     Calendar Months.  The first day of each month is used as the beginning date for each period.

·     Calendar Periods.  The beginning date of each period is specified by the user on the Planning Period Definition File.

·     Daily Intervals.  Each working day, as defined by the Shop Calendar File, is used as the beginning of a period.

When a forecasting package is used to calculate projected demand, calendar months must be used.

These four options are offered for several reporting and processing functions, as listed below.

1.   Projected demand may be entered as a quantity per period.  This quantity will be stored on file in a record containing the period start date and the forecast quantity.  For monthly entry, the forecast is held against the first week start date in the month.  This makes it easier to break a monthly forecast down to weeks at a later stage.

2.   The planning periods are used as the period over which projected demand will be compared with consumable demand to determine a "net" demand figure.  The net figure is the greater of projected or consumable demand, if the period is after the demand fence date, otherwise it is always the consumable demand.  Net demand is used in calculating the tentative schedule and in calculating available to promise.

3.   When generating a tentative master schedule, Master Scheduling "smoothes" the schedule over the weeks in a planning period.

4.   Master Scheduling plans production such that the target inventory will be available at the end of the last day or week in a planning period.

The planning period options may be used interchangeably; a different option can be selected each time a function is selected.  However, different planning period options may produce different results.  The two examples below present the same data, first using four weekly planning periods, then using one four-week planning period.

Example 1: Weekly (If weeks are after the demand fence date)

Example 2: Weekly (If weeks 1 and 2 are before the demand fence date and weeks 3 and 4 are after the demand fence date)

Example 3: Four-Week Planning Period

Because the options will produce different results, the planner is advised to select one planning period option and use it consistently throughout the system.  However, if consumable demand occurs more smoothly than in the example above, the differences in the results are less significant.