Characteristics and removal mechanism in laser cutting of cBN-WC-10Co composites

Laser cutting of a cBN-WC-10Co composite material was carried out using a pulsed Nd: YAG laser. The cutting characteristics, as well as the changes in microstructure and mechanical property, were investigated. It was found that cracks were induced by laser machining on the sub-surface and the evidence of phase transformation from cBN to hBN was observed on the cut surface. Cutting parameters had significant effect on the cut surface. A higher laser power produced a smoother cut surface, but a larger heat-affected zone, in comparison to the lower laser power used. No radical cracks were found on the cross-section at the laser power of 100 W. The surface roughness and the heat-affected zone depth decreased with the increased cutting speed and the gas pressure. The material removal involved in the laser cutting of cBN-WC-Co composite was attributed to the melting or evaporation of cBN and WC-Co. The dropping of cBN particles from the cut surface was also found during the cutting at the laser power of 30 W for the loss of the supporting from the WC-Co matrix.