Development of a micro-punching machine and study on the influence of vibration machining in micro-EDM

This paper describes the development of a novel micro-punching machine that is capable of producing precision micro-holes. A significant feature of this machine is to fabricate the micro-punch and then the micro-die in the same machine, totally eliminating the eccentricity between the punch and the die when punching is proceeded. By applying vibration machining technique, we can decrease the possibility of electric short-circuiting during the micro-EDM process. The utilization of a proportional solenoid as the power unit of the micro-punching machine and as the source of vibration is found to be a successful attempt. Experiments to punch micro-holes with diameters of 0.1 and 0.2 mm on an SUS 304 stainless steel strip with 0.1 mm in thickness were carried out. The results show that the performance of this machine and the geometry of punched micro-holes are satisfactory.     

Development of a micro-forming system for micro-punching process of micro-hole arrays in brass foil

Micro-forming technology poses much higher demands on positioning accuracy, velocity and mass production, and the common forming machines cannot satisfy these requirements using traditional drive methods. Micro-forming equipment using novel drive methods with high speed and high precision has become an important research field for industrial application. In the paper, a novel drive mechanism was designed with a symmetric distributed double linear motors and a micro-forming system was developed with micro-punching tools and automatic feeding apparatus for metal foil. The servo control system of this micro-forming system was designed using SIMOTION D445, and a parallel control model was adopted with a single motor module to solve the synchronous control problems of double linear motors. Micro-punching process of brass foil was studied with the micro-forming system, and micro-holes of 600 μm, 300 μm and 150 μm in diameter were manufactured with high dimensional accuracy. An array of 50 × 4 micro-holes, each 600 μm in diameter, was manufactured using an automatic feeding apparatus guided by a microscopic visualization system for assisted localization. The results indicate that the micro-forming system with high-accuracy and high-speed is suitable for the mass production of micro-scale parts.     

Study on vibration-EDM and mass punching of micro-holes

In this research vibration-EDM is realized by the vibrating worktable designed, which is employed in the micro-punching machine we had already developed. It is found that larger feed and better surface finish can be achieved in micro-EDM with vibration machining. Circular and noncircular micro-electrodes of diameter below 200 μm were fabricated with vibration-EDM and the setup of u-axis. Experiments to punch micro-holes of diameter 200 μm on SUS304 stainless steel and brass strips were carried out. Mass punching of micro-holes on brass strip was performed successfully, using the automatic feeding system developed. The capability of micro-punching and effects of parameters on the quality of punched micro-hole are studied.     

Punching of noncircular micro-holes and development of micro-forming

In this paper, vibration-EDM technology was introduced by the vibrating worktable designed to fabricate noncircular micro-electrodes and micro die-openings using wire electro-discharge grinding (WEDG). Micro punches and micro die-openings with different clearances were fabricated by controlling the spark gap in micro electrical discharge machining (micro-EDM). The micro-punching experiments include producing triangular and hexagonal micro-holes with a side length of 200 μm on brass strip. Punching of successive hexagonal micro-holes was also carried out successfully. The micro-forming experiments were conducted on copper and brass, producing cup-shaped protrusions with a diameter of 300 μm. All the experimental results show that the modified micro-punching machine is able to perform both micro-punching and micro-forming operations.