Scheduling with Time Buffers

Use

In Production Planning and Detailed Scheduling , if you want to protect an activity or the primary resource, on which the activity is processed, from unforeseen delays in material staging, you can schedule using a resource-specific time buffer. The time buffer represents a type of safety time: Using the time buffer, the system keeps a larger time interval between the activity and its predecessor activities during scheduling. Possible delays in the predecessor activities can be caught by the time buffer and a standstill in resources due to material shortage can thereby be avoided. Here, predecessor activities are the activities that have a time relationship or a pegging relationship to the activity.

When scheduling with time buffers, the system must – depending on the type of relationship – keep the following minimum time intervals between the activities:

In a pegging relationship, the availability date must be earlier than the requirements date by at least the duration of the time buffer.
In a time relationship, the minimum time interval defined in the production process model (PPM) is increased between the activities by the duration of the time buffer.

Note Note

If you do not specify a minimum interval in the PPM for a relationship, the system uses 0 as the minimum interval; during scheduling with time buffers, the minimum interval is therefore the duration of the time buffer.

End of the note.

In the PPM you can specify for each relationship if the system can use the time buffer during scheduling.

Scheduling with time buffers is not relevant to activities of orders that are based on an iPPE plan.

Prerequisites

General Prerequisites

You specified a time buffer in the primary resource for which you wish to carry out scheduling with time buffers.
You specified in the detailed scheduling strategy that the system should consider time relationships.

Specific Prerequisites for Scheduling with Time Buffers in Time Relationships

In the PPM for the time relationships, for which you wish to schedule with time buffers, you specified that the system can use the time buffer during scheduling (reference subtype 2) .

Note Note

Note that it often does not make sense to have a time buffer between the setup activity and the processing activity of an operation.

End of the note.

You specified in the detailed scheduling strategy that the system must use the time buffers for these time relationships during scheduling.

Specific Prerequisites for Scheduling with Time Buffers in Pegging Relationships

You specified in the detailed scheduling strategy that the system should consider pegging relationships.

You specified in the detailed scheduling strategy that the system must use the time buffers for the pegging relationships during scheduling.