Design and optimisation of micro forging system to reduce parasitic motion

As the demand for high reliability in mechanical parts increases, micro forging technology is drawing attention. In forging by a vibration tip, the straightness of the processing direction is important, and as the parasitic motion in the other direction is lower, the stress that is applied to the specimen is concentrated so that a stronger effect can be achieved. In this study, box-like, closed structure forging system to minimise parasitic displacement is designed and optimised by Taguchi method. A resonant frequency and a mode shape were analysed by means of a modal analysis. The processing direction displacement and parasitic displacement generated in the excitation horn was assessed by means of a harmonic analysis that actually added an excitation force. The displacement was measured to verify the design model and tested by very-high-cycle fatigue life testing. The results confirmed that the fatigue life was improved by micro forging.