Fabrication Of Micro Punch Molds By Micro-EDM

In nowadays, high precision, high speed and miniaturization of products are required in industries. Micro punch process, as one of micro machining technology, has the characteristics of high machining efficiency, good performance and high precision. It is very suitable for low-cost and mass production of miniature components. However, micro molds used in micro punch process have the characteristics of small-size and high hardness, which is a challenge in mold manufacturing. Micro electrical discharge machining technology removes material by high thermal energy. There is no direct contact between the electrode and the workpiece without consideration of material mechanical properties such as hardness and strength. The high machining accuracy can also be achieved by micro EDM. Therefore, it is very suitable for machining molds used in micro punch.In this paper, micro punch molds were prepared on a vertical micro EDM machine. Micro EDM control program was based on the Lab VIEW software. In 3D micro EDM milling, due to the tool radial wear and secondary discharge between the tool and workpiece, the entrance size of the cavity was larger than the exit size. The difference is called taper for short. Square cavities were machined by 3D micro EDM milling to study influence factors of taper and find the improvement of machining accuracy. The way of increasing feed depth of the tool was adopted to reduce taper, and contrast experiments under two kinds of tool feed depths were conducted. In order to increase machining stability, ultrasonic vibration was introduced and applied to machining fluid in the experiments. Experimental results showed that the introduction of ultrasonic vibration can improve to the removal of debris and reduce taper to a certain extent. By increasing feed depth of the tool, taper decreased from 3.0563μm to 0.6935μm, which proves that the increases of feed depths could effectively reduce the taper of the mold.Micro dies and punches were machined by micro 3D EDM milling technology, with ultrasonic vibration applied to machining fluid and the increase of electrode feed depth. Micro punches were machined by reverse-EDM technology. Experimental results indicate that the taper of micro dies and punches were reduced.This paper provides a new method of mold manufacturing with complex shapes. Micro punch molds are successfully machined by selecting proper machining parameters. This paper provides a foundation for the optimization of processing technology to improve machining quality and accuracy of micro die in micro EDM.