Nanosecond Laser Shock Microforming of Thin Metal Components

Laser shock microforming is conceived as a non-thermal laser forming method based on the high intensity laser induced shock waves capability to modify the tensional state of thin targets. The technique has the advantages of laser thermal forming (non-contact, tool-free and high precision), but, additionally, its minimally thermal character allows the preservation and improvement of mechanical material properties by inducing appropriate residual stress fields. In particular, the induction of compressive residual stress fields on the target surface is a desirable feature introducing additional protection of the formed parts against corrosion and fatigue crack propagation. The use of ns laser pulses provides a suitable parameter matching for the laser forming of an important range of sheet components used in MEMS that, preserving the short interaction time scale required for the predominantly mechanic (shock) induction of deformation residual stresses, allows for the successful processing of components in a medium range of miniaturization particularly important according to its frequent use in such systems. In the present paper, a discussion is presented on the physics of laser shock microforming and the influence of the different effects on the net bending angle. The experimental setup used for the experiments, the sample fabrication procedure and experimental results on the influence of repeated laser pulses on the net bending angle are also presented.