Graphite’s machining with policrystalline diamond allow the optimization of the production process: increasing productivity reducing the production cost.
It is difficult to perform any kind of deep conic bore, especially using long polycrystalline diamond cutting edges. In fact, the cutting edge must be perfectly rectilinear, although it is made with different pieces of PCD. Different thermal expansion coefficients between different materials in the welding process could influence the straightness.
However, modern self-compensating sharpening techniques (available in C.R.M. Mazzoccato s.r.l.), can ensure the perfect cutting edges and so perfect conic bores, even in graphite.