Hi Raj,
You mentioned that the factory calendar is assigned to the work center.
All the days are working days in Factory calendars assigned to the Resources (Work centers) with 24hrs operating time.
Check the factory calendar assigned to the plant. Check if it is the same in production and quality. For this, you can find the factory calendar assigned to the plant in table T001W and then check SCAL.
Kind Regards,
Mariano