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.