DEFLASHING OF PARTING LINES

so for the lumia 800-900 body, do they inject-mold it or cnc it? because i’ve seen video about n9 and they are showing cnc cutting a 80% done body case at the back part for the cameralens frames which i think it dont need cnc cutter to make the hole.
if they mold it, all the inner structure (where they put the components) are being form with sliders?
Thanks for answers, im trying to grasp on how&why the production goes :slight_smile: