High-precision Helical Cutting Using Ultra-short Laser Pulses

Abstract

Abstract The use of a helicaloptics to drill micro holes in fuel injectors and spinning nozzles has already demonstrated great advantages likehigh precision and flexibility. Due to the laser beam rotation on a helical path, the hole-geometry is almost independent from the beam shape. By slightly manipulating the beam path inside the optics, positive and negative tapered as well as straight cylindrical holes can be achieved. If the work-piece is moved relatively to the helical-optics, a helical-cutting process is performed. Compared todirect cutting technologies, helical-cutting can meet higher requirements in terms of roughness and taper of the kerf. By using a helical optics with ultra-short laser pulses, micro cutting experiments on metal and sapphire sheets were performed. As a result of the laser beamhelical movement, the roughness of the cutting kerf in metal isbelow 1 μm, and a taper less than 1 degree could be achieved with a cutting speed 10 mm/min. Recast layer and heat affected zone around the exits are negligible.