Surfacing Sleeved Blocks, or Cylinder Heads with Steel Insert has always been a challenge in the engine machine shop. To fix this becoming common issue, custom geometry must be applied.  Most machines run negative rake insert holders, which works great for Cast and Aluminum, but Not Bimetal..  Geometry must be updated to positive rake to lift the chip to prevent smearing.  Also, CBN must be applied, as any PCD would Fracture when cutting the steel or iron. As a bonus, Positive Rake PCD works INSANE on bare Aluminum if want an ultimate finish! So we make both CBN and PCD Inserts.  Update Your Shop Today with Performance CBN Positive Rake Inserts, Insert Holders, or Complete Flycutter System, adaptable to almost ANY System!