CNC Diamond PCD and CBN Turning Inserts PCD is formed in a large High Temperature-High Pressure (HT-HP) press, as either a diamond wafer on a backing of carbide, or forming a "vein" of diamond within a carbide wafer or rod. PCD is no good for cutting steels for similar reasons, except substitute carbon (what diamond is made from) for nickel. That's why diamond is pretty much exclusively used for non-ferrous/fiberglass/composite materials. Oddly, it is still able to be used and recommended to cut carbon fiber. PCD is for any speed, period, in nonferrous materials. It will leave a good finish at low surface speeds, and it won't break down at ridiculous speeds (10k+ sfm). It also lasts much longer than any other type of insert, usually orders of magnitude longer. PCBN is made by high pressure high temperature sintering of cubic boron nitride with a binder pahase, and there are mainly tow...
