Carbide makes a wonderful cutting tool but isn't my first choice for a fly cutter. The downfall of most carbide (insert, bit, solid) is in shock. It causes micro fracturing of the edge and this quickly leads to chipping. This doesn't present itself in a multi-insert gang cutter, solid end mill, or any other tool that has keeps the shock to a minimum. With a single insert/bit tool like a fly cutter the carbide gets slammed into the material every revolution with nothing to balance/distribute the shock load. An interrupted cut will just beat the chicken soup out of carbide. Yes you can use carbide in a fly cutter but tool life is not going to be as long as carbide is capable of. Even the rigidity of the machine can affect it. Carbide needs a rock solid machine to realize the benefits of it. HSS needs to be run slower but will take more of a beating than carbide and you can easily sharpen it yourself. Carbide when it chips will often need up to 1/32 removed from the edge to get past the fracture line. Hss just gets dull if you run the SFPM formula correctly. I prefer to save the carbide for hardened material. Even when cutting castings I'll often use HSS to bite through the "skin" and then resharpen for my final pass. HSS may not be capable of the speeds/feeds as carbide/ceramics but it still has a place as a cutting tool of choice. JMHO.  |