Scheduling for Sub-Operations

Hi All,

I am having a Production Order for which the routing contains operations and sub-operations. After the scheduling is carried out: the Processing time for every Operation is calculated as Operation Qty * Std value[Duration].

That is, 30 Kg * 3 Hrs = 90 Hrs.

The workcenters assigned to the Sub-operations also work on the same scheduling formula. But for all the sub-operations, the processing time is calulated as something else. We expected it to show same as the Operation's, that is 90 Hrs fro sub-operations as well. But instead it appears as 7.3 Hrs.

I have been looking for the detailed documents over this topic but could not find any.

Please provide relevent information over this topic with some examples---> How Sub-operation scheduling is carried out ? and what all fatcors can effect it ?

Regards,
Avinash