Product Code: ICA12_M1205

Laser-Beam Helical Drilling of High Quality Micro Holes
Authors:
Christian Fornaroli, Fraunhofer Institute for Laser Technology ILT; Aachen Germany
Jens Holtkamp, Fraunhofer Institute for Laser Technology ILT; -
Arnold Gillner, Fraunhofer Institute for Laser Technology ILT; -
Presented at ICALEO 2012

A large variety of modern components and products such as fuel injectors and spinning nozzles require holes drilled to very high standards with regard to roundness, diameter and aspect ratio. Laser-beam helical drilling has shown great promise to produce these high quality micro holes. In helical drilling the laser beam is moved in rotation relative to the work piece. In this case, the rotational movement is produced using a Dove prism, mounted in a high speed, hollow shaft motor. If the beam is shifted parallel to the optical axis, the outgoing beam moves on a circular path; if, however, it is tilted in front of the prism, the outgoing beam traces the shape a cone. Helical drilling allows the production of exact cylindrical and round holes in the range of 50 micrometer as well as negatively tapered holes. In this paper the main influencing factors on quality and productivity, such as type and pressure of process gas, fluence and rotational speed are investigated. For this a ns pulsed laser source with a wavelength of 532 nm is used when drilling work pieces made from steel with a thickness in the range from 0.3 mm to 1 mm.