Defining the Work Week

About Shift Intervals

A shift specifies the set of time periods (called shift intervals) used to determine when resources on that shift are "up" or available to work on operations.

You specify shifts in terms of weeks. This weekly pattern repeats for all weeks within the Scheduling Horizon. A week starts Sunday morning at 00:00:00 and runs until Saturday at midnight. All periods within a week not specified with an interval period are assigned as not working, or down. Daily cycles do not automatically repeat. You must define each daily interval separately.

Note: You should never cross Saturday at midnight within a shift interval. If you have a shift that must extend past midnight, you can allow it to do so on other days. But on Saturday, make that shift interval end at 24:00 and create another interval that starts at 00:00.

How Resources Use Shift Intervals

Resources may use more than one defined shift, and the shifts can overlap. The system considers the resource available during any of its shifts including an overlap period.

When a shift reaches the end of an up interval, resources on that shift become unavailable. By default, any resource currently processing stops processing when its shift goes down.

Note: In the Scheduler, the load with the allocated resource uses the resource's Allocation setting to determine whether to wait for the same resource or to try for other resources.

See Handling Resource Reallocation During Interruptions.

If an operation requires multiple resources that are on different shifts, the operation can only be in process when all its required resources are in an up interval. For example, suppose the operation requires three resources:

Resource A: on-shift from 08:00 - 16:00
Resource B: on-shift from 10:00 - 18:00
Resource C: on-shift from 12:00 - 20:00

In this example, the operation could only be in process between 10:00 and 16:00.

About the Shift and MDAY Calendar

By default, the scheduling shift runs from Sunday to Saturday. Its primary purpose is to determine valid manufacturing or business days, which the system loads into an internal "MDAY calendar" that it reads when running these processes:

Material Availability Report
MPS Processor (to determine if a receipt is within the reschedule tolerance factors of a requirement so it can generate a Reschedule exception, and to calculate the date MPS records need to be released by in order to generate a Release Order (MPS Item) exception).
Material Planner Workbench (when using safety stock or cross-reference method).
The Forecast form (when calculating forecast consumption by customer orders).

When generating the MDAY calendar, the system reads the Shift ID to determine the valid manufacturing work days. Valid manufacturing days are those where the Minimum Hours in Work Day parameter (defined on the Planning Parameters form) is less than or equal to the total hours in the day on the shift. It enters a day on the MDAY calendar for all of the valid manufacturing days between the MDAY Start and MDAY End dates (also defined on Planning Parameters). The hours specified for each day on the shift determine the total available hours for each day in the MDAY calendar. The system updates the MDAY calendar any time you change the shift or MDAY Start/End or Minimum Hours in Work Day parameters.

You cannot delete the shift.

About the Lead Time PCAL Shift

By default, APS accumulates lead time for items based on a 24-hour day and 7-day week. If you want to exclude certain days (such as weekend days) from the lead time calculations, you must create a shift named "PCAL" and specify the "working" days. APS ignores days not specified in the PCAL shift when it performs lead time calculations.

Example Work Week

This example illustrates three typical 8-hour working shifts: 1st, 2nd, and 3rd shift. Each shift overlaps the previous shift by 30 minutes and contains a 30-minute lunch period:

1st Shift: 06:00-14:30 Mon-Fri
2nd Shift: 14:00-22:30 Mon-Fri
3rd Shift: 22:00-06:30 Sun-Thu (the third shift starts the week on Sunday night)

To represent this shift pattern on the Scheduling Shifts form, enter three records as shown in the pictures below:

1st Shift

The first shift starts each day at 6:00 a.m. and ends at 2:30 p.m. However, to account for the 30-minute lunch period, you define it on the form as an 8-hour period rather than 8.5 hours.

After creating the first interval, use Actions > Copy to create the remaining intervals in the shift. For example, after creating Monday's shift interval, select Actions > Copy and change the Starting Day and Ending Day to Tuesday. Then select Actions > Copy again and change the Starting and Ending Days to Wednesday, and so on.

2nd Shift

The second shift starts at 2:00 p.m., 30 minutes before the first shift ends, and runs to 10:30 p.m. Again, you define the shift to end at 10:00 to account for the 30-minute lunch period.

3rd Shift

The third shift starts at 10:00 p.m., 30 minutes before the second shift ends, and runs to 6:30 a.m. the next day. As with the first and second shifts, you define the shift to end 30 minutes earlier to account for the lunch period.