Formability of micro-gears fabrication in laser dynamic flexible punching

Abstract

A novel laser dynamic flexible punching process is employed to fabricate micro-gears to address the difficulties in punch-to-die alignment in the conventional micro-punching process. In this process, induced shockwaves act as micro-punches and soft punch acts as the media to transmit pressure. The influences of laser intensity, foil thickness and grain size on dimensional accuracy and rollover diameter have been investigated experimentally. In addition, the changes in the hardness and elastic modulus of the workpiece after the laser shock effect are characterized by nano-indentation experiments. It is revealed that the dimensional accuracy is optimal when the laser intensity is 5.6GW/cm2, but the laser intensity has little effect on the rollover diameter. Punched gears of thicker foils result in worse dimensional accuracy and larger rollover diameter. Foils annealed at 350°C achieve the best punching accuracy but compromise with regard to the maximum rollover diameter. Furthermore, both the nano-hardness (9.92%) and elastic modulus (14.37%) are improved after the laser shock effect, as the evidence of an increase of surface strength and material stiffness. The proposed method, laser dynamic flexible punching, will potentially lead to new methods for micro-gears fabrication in the future.