Terminology (Project Manufacturing and Make-to-Order Manufacturing)
This is an overview of terms that are relevant for project manufacturing and make-to-order manufacturing with planning-related intervals:
Planning-related minimum interval
Planning-related offset
Process-related minimum interval
Offset (process-related)
Float
Earliest and latest dates of an operation
Critical path
Critical operation
Network delay
Planning-related minimum interval
= Minimum interval between two activities of different operations of an order, which must be adhered to for technical planning reasons
The following conditions apply:
The planning-related minimum interval must be greater than the process-related minimum interval.
The planning-related minimum interval must be smaller than the maximum interval.
The planning-related minimum interval can be changed in the detailed scheduling planning board and the resource planning table.
Planning-related offset
= Interval between requirement (input node) and start of the activity
The following conditions apply:
The planning-related offset must lie before the offset that is defined in the master data as the "process-related" offset.
The planning-related offset must be greater than the (process-related) offset.
The planning-related offset can be changed manually in the detailed scheduling planning board and the resource planning table.
The planning-related offset can also refer to the interval between the requirement and the end of the activity, if the requirement is linked to the end of the activity.
Process-related minimum interval
= Minimum interval between two activities of an order that the interval must not fall below because of restrictions that apply to the procedure or to the equipment, for example.
The following conditions apply:
In the detailed scheduling planning board and the resource planning table, the process-related minimum interval can only be displayed.
Offset (process-related)
= Period that is added to or subtracted from the start or end time of the activity in order to determine the time at which material consumption occurs
The following conditions apply:
In the detailed scheduling planning board and the resource planning table, the offset can only be displayed.
Float
= Interval between the earliest and the latest position of the operations in the network
The earliest and latest position of operations is determined during calculation of the critical path by a backward scheduling run followed by a forward scheduling run.
The difference between the earliest and the latest position of the operation in the network is called the float.
The float is a gross value meaning that it also includes non-working times (weekends, breaks, and so on).
Earliest and latest dates of an operation
= Earliest and latest start and end dates of operations of one order
The system calculates these dates, taking into account the preceding and succeeding orders that are linked to the order via pegging relationships, and the validity. When making the calculation, the system treats these preceding and succeeding orders as fixed.
In the heuristic for calculating the critical path, the system determines the earliest and latest position of operations in the whole network (and not the earliest and latest start and end dates of operations within the order).
Critical path
= Group of operations with a small float, or no float, in a network of orders. (These operations do not necessarily have to follow one another directly.)
As a result, delays in the critical path lead to a delay in the whole project.
In SCM, you can reduce planning-related minimum intervals and planning-related offsets to reduce the total execution time.
Critical operation
= Operation with a float that was determined using the heuristic for calculating the critical path and that is smaller than the threshold value defined in the heuristic
Network delay
= Period of time by which the network extends into the past