PCD and CBN Gun Drills: When Superhard Tooling Makes Sense for Deep Hole Drilling
Carbide is the standard for gun drilling, but it is not always the best choice. In specific applications — high-silicon aluminum, hardened steels, and abrasive composites — PCD and CBN gun drills can outlast carbide by 10-50x. The catch is that these tools are expensive, brittle, and require a rigid setup. Here is what I have learned about when they work and when they do not. What PCD and CBN Are PCD (polycrystalline diamond) and CBN (cubic boron nitride) are superhard materials. PCD is the second-hardest known material after natural diamond. CBN is the second-hardest after PCD. ...