Influence of the laser parameters on the cutting edge preparation and the performance of cemented carbide indexable inserts

摘要

Laser machining has a high potential for the preparation of cutting edges. However, the heat input through the laser beam may change the properties of the cutting tool material. These changes can in turn affect the performance of the tool. In this paper, the surface roughness, the chemical composition, the phase composition, the surface residual stresses and the hardness in the surface layer of differently laser machined specimens made of cemented carbide are analyzed. In the second step of the investigations, laser machining was used for the preparation of cutting edges. The laser parameter settings applied for the preparation were varied. The analysis reveals that the surface, the surface integrity and the tool performance are significantly affected by the parameter sets used for laser machining. The decisive factor is the efficiency of material removal. The less heat dissipates from the processing area into the adjacent material, the more efficient the material removal, and the lower the surface roughness and the undesired alteration of the sub-surface properties. Laser parameter sets that only slightly influenced the properties of the cemented carbide resulted in a better tool performance in comparison to those that altered the properties of the cemented carbide more strongly. The most important laser parameter in our study was the pulse duration. Pulse durations in the range of picoseconds considerably reduced tool wear compared to pulse durations in the order of nanoseconds. This is mainly due to the smaller tensile residual stresses in the surface and the better mechanical material properties in the surface layer in the case of the shorter pulse durations.