blade

Although cubic boron nitride (CBN) inserts are expensive, CBN inserts are best suited for hard turning. CBN inserts can maintain the same positioning during intermittent cutting and provide a safe tool wear rate during continuous cutting. When using a reasonable hard turning process, CBN inserts are second to none in terms of controlling diameter tolerances compared to grinding.

Ceramics are not as wear-resistant as CBN, so they are generally not used for machining with tolerances less than ± 0.025mm. Ceramics are not suitable for intermittent cutting, and coolants cannot be added because thermal shock may cause the inserts to crack. The blunt edge geometry of the insert is an inherent feature of ceramic materials, which increases cutting forces and reduces the surface finish of the workpiece. In addition, ceramic blade edge breaks can be catastrophic, which can render all cutting edges unusable. Cermet (cubic titanium carbide) is effective for continuous cutting of carburized hardened materials. Although it does not have the abrasion resistance of CBN, the insert will wear in most cases without breaking. Positive rake angle inserts are usually used for hard turning on machines with low rigidity due to their small cutting forces. Regarding the most reasonable application of inserts, it is recommended to work closely with the tool supplier, especially at the initial stage, to quickly reach the optimal cutting speed.