A study on micro hydroforming using shock wave of 355 nm UV-pulsed laser

Graphical abstract: In this paper, we propose a new manufacturing technology of microhydroforming using a 355-nm ultraviolet (UV) pulsed laser. Hydroforming is a technology well suited for manufacturing of metallic parts, especially in the case of mass production, because such parts are required in many industrial products. In addition, laser shock processing (LSP) has been developed to expand the applications of microdevices and equipment. Photochemical, photothermal, and photomechanical phenomena occur when a material is subjected to LSP. In particular, the photothermal effect due to pulsed laser irradiation makes accurate processing difficult. To reduce the thermal effect, we conducted laser irradiation experiments with the sample immersed in water. The underwater condition provides liquid pressure that can aid in the manufacture of the desired material. We also conducted simulations using the finite element method. Compared with conventional processing technology, our new method can provide high selectivity and efficiency while simultaneously lowering the manufacturing costs for parts with complex shapes. - Highlights: • New microhydroforming using a 355-nm ultraviolet (UV) pulsed laser was introduced. • Laser irradiation with the sample immersed in water to reduce thermal effect. • Underwater condition provides liquid pressure to manufacture the desired material. • We conducted simulations using the finite element method compare with experiment. - Abstract: In this paper, we proposed a new manufacturing technology of micro hydroforming using 355 nm ultraviolet(UV)-pulsed laser. Hydroforming is known as a well-established technology to manufacture metallic parts, in particular for mass production of sheet metal, for several industrial applications such as automobiles, battery and military products. In addition laser shock processing(LSP) has been developed as the expanded applications of electrical and mechatronic devices. When the material was exposed to laser beam, multiple phenomena like the photochemical, the photothermal and the photomechanical effect are simultaneously occurred at the spot area. Especially, the photothermal effect due to laser heat transfer makes it hard to improve the accuracy of laser processing. To reduce the thermal effect and to enhance the photomechanical effect, the laser was irradiated under water in this paper. Strong forming pressure of LSP was provided by the higher density of water than air, which could help directly manufacture the thin sheet metal materials like as laser direct writing. We also conducted computer simulation using finite element method(FEM) to demonstrate its deformation behaviour with and without the strain rate effect of 10⁴–10⁵ (sec⁻¹). Compared with conventional processing technology, this new method can provide high selectivity, excellent hydroforming efficiency and lower cost to achieve micro grooving pattern on the surface of thin metal sheet.