scrap material

I am using material type for daily transaction

ROh, HAlb, FErt,

i have created zscap material type for scrap transaction at all stages.

after routing on the roh say out of 10 matrials , 2 mat. are scrap.

so now my client wants this halb material should be convert in to zscrap material type & after that it will further proceed for sale .

How to map this scenario in SAP.

please help.