Fabrication Of Micro Punch Tools By Micro-EDM

The concept of product miniaturization has greatly promoted the development of micro-machining technology, with the increasing demand for miniature products, social development also demands a higher micro-machining efficiency. As a micro-machining technology, micro punching machining shows huge potentials in low-cost and mass fabrication of miniature components. However, the hard fabrication of small-size and high-hardness precision molds used for those miniature components hinders the wide application of micro punching technology. Micro-EDM (Electrical Discharge Machining), one of micro-machining technologies, enjoys a big advantage in the processing of high hardness and conductive materials based on its special machining principle, which is particularly suitable for the fabrication of micro molds.In this study, micro punch tools were prepared on a vertical micro EDM. To make the punch by reverse-EDM, a reverse electrode, which is a through hole and has the same shape as the punch, was firstly machined by a micro tungsten electrode on a brass sheet. Then the punch blank moved slowly downward to the reverse electrode to implement the reverse-EDM of the punch. During this process, not only a large amount of material should be removed, but also a small discharge energy must be used to get a good surface quality, which lead to a low machining efficiency. To improve the efficiency of processing, this paper applied ultrasonic vibration to dielectric fluid. In this study, two different vibration modes were used. In the first mode, ultrasonic vibration was led by a metal ship into processing region above the reverse electrode in order to vibrate the machining fluid, and its effect on the efficiency of micro-EDM was analyzed. The results showed that the removal of debris and the machining efficiency were improved, and the discharge gap was reduced. It was found that the vibration distance and vibration transmission material also had a significant impact on the efficiency of processing. In the second mode, the dielectric fluid under the reverse electrode was vibrated by an ultrasonic vibrator. The comparison of the performance of reverse-EDM with and without ultrasonic vibration indicated that the efficiency of micro-EDM is improved, the discharge gap and electrode wear is reduced with the vibration of dielectric. After comparing the effect of the two vibration modes, it was found that the vibration of dielectric fluid under the reverse electrode has better machining efficiency.In this study, ultrasonic vibration was applied to machining fluid, special-shaped micro punch tools were fabricated by3D micro-EDM technology and reverse-EDM technology, and statistical analysis of dimension error of micro punch tools was performed. The final results showed that, with appropriate processing technologies, micro punch tools with precise dimensions and good surface quality could be fabricated by micro-EDM.