Chances and Limitations in the Application of Laser Chemical Machining for the Manufacture of Micro Forming Dies

¹ BIAS – Bremer Institut für angewandte Strahltechnik, Bremen, Germany
² Leibniz Institute for Materials Engineering, Laboratory for Precision Machining LFM, Bremen, Germany
³ University of Bremen, BIMAQ – Bremen Institute for Metrology, Automation and Quality Science, Bremen, Germany
⁴ University of Bremen, Faculty of Production Engineering-Mechanical Engineering & Process Engineering, Bremen, Germany

^* Corresponding author: messaoudi@bias.de

Abstract

Laser chemical machining, a non-conventional processing method based on thermally activated electrochemical material dissolution, represents a promising technology for manufacturing metallic dies for micro forming applications. Prior to widespread industrial acceptance the machining quality of laser chemical machining should be characterized. For this purpose, laser chemical machining is compared with micro milling regarding both the dimensional accuracy and the surface quality. Therefore, square micro cavities exhibiting side walls between 100 μm and 400 μm in length and 60 μm in depth are machined with both manufacturing processes into the cobalt-chrome alloy Stellite 21. The geometrical features are investigated using laser-scanning confocal microscopy and scanning electron microscopy. On the one hand, laser chemical machining is more suitable for manufacturing cavities with dimensions < 200 μm due to higher shape accuracy with stable mean edge radii of (11.2 ± 1.3) μm as a result of roughing and finishing steps. On the other hand, the finish quality of micro milling with mean surface roughness Sa of 0.2 μm could not be achieved with laser chemical machining due to in-process induced waviness. Finally, the metallographic analysis of the surface-near layers reveals that both manufacturing processes ensure gentle machining without any noticeable micro structural impact.