Morphologies of Cemented Tungsten Carbides Irradiated by Femtosecond Laser with High Pulse Energy for Machining Enhanced Cutting Tools

Recently, ultrafast laser machining has been used to machine hard materials. Ultrafast laser machining can be precisely machined without a non-thermal effect or damage to machining tools. However, their morphologies differed depending on the pulse energy. Generally, to machine difficult-to-machine materials, hard materials are irradiated by laser pulses with high pulse energy. Laser pulses with high pulse energy remove large volumes. However, burrs are formed at the top surface, and the large volumes removed remain empty. These burrs and empty spaces reduce the efficiency of the process. Owing to these problems, the formation of burrs must be restricted during laser ablation. Accordingly, this work aimed to reduce the formation of burrs and improve the machining efficiency. In this study, to overcome the aforementioned undesirable effects, the position of a focused laser beam with a high pulse energy was altered when irradiating cemented tungsten carbides; the laser had a pulse duration of 190 fs, wavelength of 1026 nm, frequency of 6 kHz, and pulse energy of 100 µJ. When focused laser beam was irradiated at the ablated bottom surface, the laser machining efficiency increased. Moreover, the position of the focused laser beam affected the morphology of burrs. On focusing the laser beam at the surface, burrs with shorter heights and larger lengths were formed. The morphologies of these burrs and the ablated space affected the laser passing rate and machining efficiency.