Hi
As I understand, you are thinking of consignment process for your business process from goods ownership point of view. And bit you are confuse, b'coz you are sending Material A, but in return you are getting Material B.
For your Business process, this generally terms as Subcontracting or Job work, where material ownership remains with you, but you sent Material A and receive Material B.
For further if you are looking for more information on Subcontracting/Job work, kindly search and you can come up with specific queries while configuring or running a test cycle in your system. Or you can refer SAP Help for understanding.
If my understanding is not in line with your requirement, kindly elaborate your business process.
Thanks,
JP