Date and Time Calculation for WOs

This document describes how the calculation of date and time works for work orders, and what to check if you think the result is incorrect.

Variants

There are two main variants of this functionality, controlled by the MO lead time method on 'Item. Connect Facility' (MMS003/F).
- 0-Manual lead time. No calculation takes place. Dates are kept as specified.
- 1-Automatic. Lead time is calculated based on operation runtime, lead time offset, or manually set lead times in 'Service. Open' (MOS300) or 'Item. Connect Warehouse' (MMS002).
  This setting in (MOS300) can be overridden using parameter '197 Manual override lead time method' in 'Work Order Type. Open' (MOS120). This allows a specific order type to behave as if the parameter is set to 0 in (MOS300).
Parameter '080 Should maintenance limits affect start/finish dates' in (MOS120) controls if the WO should use forward or backward planning.
Transit time (SLAC) between operations is calculated if it has been set up in 'Work Center. Enter Queue & Transit Time' (PDS020).
On the facility record in 'Facility. Open' (CRS008) you can define if shift planning should be used or not. If it is not, then the time fields are not displayed on the orders.
Time zone handling is controlled using the F13 setting in most programs.

MO lead time method 0 - manual

Dates specified at order creation are retained. Operations are given the same date and time as the order header.

MO lead time method 1 - automatic

Note: No record in (MMS003) means that automatic lead time is used.

Equipment calculation is done automatically when you leave (MOS300) after editing or adding a service. It can also be manually triggered using related option 21='Equipment Calc' in 'Service. Connect to Facility' (MOS301). The calculation is performed in the background through function program PDS900 (Calculate DBF and leadtime).

The product or equipment calculation starts from the operations runtime or setup time, the work centers' capacity per person, and the utilization rate. Equipment calculation always starts from the last operation number and calculates how many days the operation will take. That results in a value for 'Production days' and 'Lead time offset'. Lead time offset is the number of days from the finish date that the operation should start. For each previous operation the lead time offset is added so that the first operation gets the total number of days that is required for the job.

Note: Transit time is set up on local facilities and is not included in the calculation if the service is defined on a consolidated facility.

Work center capacity

Capacity can be created based on the settings on the work center, capacity, number of workers, and utilization rate. It can also be based on the employee calendar in 'Employee. Connect Calendar' (CRS510) for the employees connected to the work center in 'Person. Open' (CRS530). The method is specified in 'Settings - Capacity Requirements Planning' (CRS786).

If shift planning is activated in (CRS008), and shift schedule has been set up in 'Shift Pattern. Open' (PDS033) and 'Shift Pattern. Open Lines' (PDS034), and shift model set up in 'Shift Model. Open' (PDS031) and 'Shift Model. Open Lines' (PDS032), daily capacity is created based on the shift pattern and the system calendar in (CRS900). If the shift is not working on weekends, there will be records in the daily capacity only for days set to 'General capacity' in 'System Calendar. Open (CRS900). If the shift is set up for 7 days but no working time for weekends, the days are then created in the daily capacity, but no capacity is available. If a lunch break is defined in the shift pattern or two real shifts are defined, two records for each day is created.

If shift planning is not used, then daily capacity is not used. In this case the general capacity days in (CRS900) are used as working days.

Planned WOs

Automatic lead time calculation with shift planning:

When a planned WO is created manually in 'Work Request. Open' (MOS170) or from 'Maint CO. Quick Entry' (COS130) or 'Maintenance Customer Orders. Open Line' (COS101), or from 'Work Request. Quick Entry' (MOS185), or using service requirements planning (SRP), 'Work Request. Create Work Order' (MOS912) creates or recalculates the dates. Depending on parameter '080 Should maintenance limits affect start/finish dates' in (MOS120) you can specify and consider start date or finish date. First the planned WO header, operations, and material lines are created. Then each operation is analyzed, retrieving the estimated time, checking capacity for each day in 'Work Center. Update Daily Capacity' (PDS016) and the number of days required is calculated. For each operation the dates in 'Work Request. Open Line' (MOS171) are updated for operations and connected material. The time is the start and end time for the shift in (PDS016).

Note: The exact time of the day the operation will be finished is not considered, as it is on released WOs.

When operations are changed, added, or deleted in (MOS171), the dates are recalculated in (MOS912) in the same way as when operations are created. This also happens if the API transactions AddOp, ChgOp, or DelOp in MOS170MI are used.

Automatic lead time calculation without shift planning:

In this scenario, there are no fields with time of the day to use and no daily capacity in (PDS016). So, the calculation is only based on days with general capacity in (CRS900). Apart from this exception the functionality works identically to automatic lead time calculation with shift planning.

Released WOs

During release and when operations are changed, added, or deleted in 'Work Order. Open Line' (MOS101) during rescheduling the dates and time are calculated through function program MOS905 (Calculate leadtime on work order). The biggest difference as compared to planned WOs is that time of the day is considered on a detailed level. So if an operation takes three hours and we have a specific start or finish date we know that the operation will run between 08:00 and 11:00 if the work center shift starts at 08:00. This is applicable if shift planning is activated, if it is not, only the dates are calculated, the same way as they are on planned WOs.

What can go wrong

Incorrect capacity:

Is capacity for the work center generated for the year? If not, regenerate using 'Work Center. Change Capacity' (PDS015) or (PDS016).
Is general capacity set correctly? Check the system calendar and review weekend settings.
Has the shift pattern date expired? View (PDS034).
Are the shift model lines correct? View (PDS032).
Is the capacity based on the work center capacity or the employees in the work center? View (CRS786).
- If capacity is based on employees, check the employee calendars for all employees that are connected to the work center, using (CRS530) or (CRS510).

Incorrect dates on planned WO, WO, or operations:

Verify capacity settings as for incorrect capacity issues.
Is the transit time correct? Check the setup in (PDS020) for the local facility. Verify the transit U/M and overlap code in 'Work Center. Open' (PDS010) and 'Product. Connect Materials/Operations' (PDS002). Check the utilization rate in (PDS010).
Is forward or backward planning used? Check parameter 080 in (MOS120).
What is the setting for 'MO lead time method' in (MMS003)? If there is no record in (MMS003) automatic lead time is used.
- Check parameter '197 Manual override of lead time method' in (MOS120).
Verify that the time zone settings using F13 in WO programs are correct.

Incorrect dates or time on the MCO lines or planned WO connected to an MCO:

Verify that the time zone settings using F13 in MCO programs are correct.