Laser machining of cobalt cemented tungsten carbides

In comparison to the far greater acceptance of laser beam machining, little is still known on how the two-phase material responses to the impact of the laser beam (surface damage). Currently, few scientifically grounded, technological data are available on the removal of hard metals by using laser beams. This study investigates the impact of laser radiation (wavelength of 1,064 mn) in ns pulse range on various hard metal configurations. In addition to the removal behaviour, the resulting surface damage as well as surface roughness were studied as target parameters that can be influenced. As radiation source, a Q-switch-Nd:YAG laser is employed, as is common in the majority of 3D laser micro machining concepts. In experiments, the impact of influencing parameters relevant to the process is determined, such as the light's current intensity, repetition rate, and scanner feed velocity, on the qualitative and quantitative target values of surface roughness, layer removal rate, and surface integrity impact. Comparative investigations of hard metals with different grain sizes were performed to determine the impact of this material characteristic on the machining process. In this research the mean grain diameters of tungsten car-bide were varied by using grain sizes ranging from ultra fine to standard grains. The results on laser machining of cobalt cemented tungsten carbide demonstrate the suitability for micromachining small three-dimensional geometries. A possible application field for micro tools is shown in the paper.