Hi
This is similar to what happens in pharma industry. Massive cleanup and set up time is needed before making any new medicine on a machine.
In your case, if the set up time for C is gonna be 2880 min irrespective of the predecessor product on the machine, then this set up time should be charged to C
I think the challenge would be that if D is made before C and has same diameter, then C won't require much of set up time. Is that right?? If yes, I would suggest have same 2880 for both or arrive at some average. There will always be variances due to set up time and management must beaware of this
Ajay M