The Effect of Cavitation Water Jet Shock as a Newly Technology on Micro-Forming Process

Abstract

This article proposes a novel technology called water jet cavitation shock micro-forming to fabricate micro-features on 304 stainless steel foils with a thickness of 100µm, using a cavitation nozzle with an incident pressure of 8 to 20MPa. This study investigated the surface morphology of the formed part, the influence of incident pressure, target distance, and impact time on the forming depth, and analyzed the punching phenomenon of the formed components. The experimental results after the water jet cavitation shocking indicated that the surface morphology of the formed part of the 304 stainless foil sample had good quality and no conventional defects such as die scratches and cracks. Furthermore, when the incident pressure was 20MPa, the height of the uniform-shaped spherical cap exceeded 262µm. The forming depth increased with increasing incident pressure and impact time. Under an incident pressure of 20MPa, with the increase of target distance, the average depth of the formed part increased at first and then decreased. Finally, the analysis of the blanking phenomenon indicated that when the incident pressure increased to 30MPa, the workpiece was completely blanked. This is mainly because, under this incident pressure, the shockwave pressure generated by the collapse of the bubble deforms the workpiece beyond the stress limit of the material itself.