Generation of Rotationally Symmetric Micro Tools using Ultrashort Laser Pulses

We report on the fabrication of rotationally symmetrical geometries with ultrashort laser pulses impinging the constant rotating workpiece tangentially. This particular micro machining of geometry is referred to as laser turning, upon which the laser beam is, in general, oriented perpendicularly to the rotational axis and tangentially to the work piece. The target geometry is realized by moving the constantly rotating specimen according to the specified geometry along the focused laser spot. In contrast to mechanical turning, laser turning induces a minimized amount of lateral forces through friction that might deteriorate the geometry. In this study, laser turning is examined for stellite as a function of pulse energy and pulse length in the range between 240 fs and 10 ps. Shorter pulse lengths and higher pulse energies increase the achievable ablation rate, while in the pulse length regime of below 1 ps lower roughness is achieved. With a maximum ablation rate of 1.27 mm/min and a minimum roughness of 0.17 m, laser turning combines both, fast processing and high surface quality.