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Helical drilling of high-aspect-ratio microholes in stainless steel using ultrashort laser pulses

 
: He, Chao; Weber, Malte; Gillner, Arnold

Wissenschaftliche Gesellschaft Lasertechnik -WLT-:
Lasers in Manufacturing, LiM 2019. CD-ROM : Munich ICM, Internationales Congress Center München, Germany, June 24-27, 2019 : World of Photonics Congress
Erlangen: WGL, 2019
6 pp.
Lasers in Manufacturing Conference (LiM) <2019, Munich>
World of Photonics Congress <2019, Munich>
English
Conference Paper
Fraunhofer ILT ()
ultrashort pulse laser; microdrilling; helical optics; stainless steel; high-aspect ration

Abstract
Laser-beam helical drilling with ultrashort pulsed lasers is one of the few techniques for producing high precision microholes, which demonstrate excellent wall definition and small heat-affected zone. This study is aim to achieve a laser direct fabrication of high-aspect-ratio microholes in stainless steel with thickness of 1.2 mm and 3 mm. By using the helical drilling optics, the multi-reflection behavior in the bore channel can be adapted by changing the incident angle and helical path of laser beam. By taking advantage of this, the deep drilling with minimized hole-diameter is enabled. Influences on hole-profiles and hole-quality by processing parameters such as laser focal position and helical optics are presented and discussed. Quasi-cylindrical holes with diameter of approximately 60 μm and a depth-to-diameter ratio greater than 20:1 and 50:1 can be fabricated in a 1.2 mm and a 3 mm thick stainless steel respectively.

: http://publica.fraunhofer.de/documents/N-577875.html