Laser formation of chip breaker onto sintered c-BN cutting insert for precision cutting

A chip breaker with a thin pattern was formed on the surface of a sintered c-BN (cubic boron nitride) cutting insert using a laser technique. The material was processed in liquid to prevent the formation of a detri–mental heat–affected zone on the processed surface. This study was initiated to determine the best–suited liquid. Various liquids such as KOH, KNO₃, and NaNO₃ solutions of various concentrations, and pure water were subjected to the experiment. The processed surfaces were evaluated using instruments such as scanning electron microscope and wave dispersive X-ray analyzer as well as the surface-roughness measuring system. It was found that the surface processed in a KOH solution of 30 % is the most suitable. Then, the effect of the prepared chip breaker groove was evaluated by a cutting test of a hardened steel rod on a lathe. The results show that the chip breaker that was formed on the cutting insert was effective in that it achieved the successive breaking of ribbon-like strips into small pieces.