Investigation of the Cavitation Micro-Forming Mechanism and Forming Characteristic of 1060 Aluminum Foil Between Parallel Walls

This study systematically investigates the dynamic behavior of laser-induced cavitation bubbles and the micro-forming mechanism between parallel walls. The bubble is produced in the middle of the gap. Through integrated high-speed imaging, hydrophone detection, and numerical simulation, the dynamic behavior of cavitation bubbles under parallel-walls confinement is analyzed. The results reveal that bubble oscillation, collapse patterns, and jet formation are governed by the dimensionless parameter ρ (the ratio of bubble diameter to gap distance). Distinct regimes are identified: bubble splitting and dual-jet formation occur when ρ ≥ 0.6, while shock waves exhibit multiple peaks due to inter-wall reflections. Both the plasma shock wave and the first collapse shock wave generally increase with gap distance. Material deformation characteristics are evaluated under varied laser energies and gap distances. Specimens formed at 40 mJ with D ≤ 2 mm display clear fillet features. Surface roughness first decreases and then increases with gap distance, reaching a minimum of 1.82 μm at D = 2 mm. Forming depth increases with laser energy and decreases with gap distance, achieving a maximum of 88 μm at D = 1.2 mm. The most pronounced thinning occurs at the bottom area. These findings establish a theoretical foundation and provide a practical process window (ρ ≈ 0.79–1.03) for optimizing parallel-walls cavitation micro-forming of ultra-thin materials in confined spaces.