Papers by Author: Yong Bin Zeng

Abstract: Manufacture of micro holes in difficult-to-machine material is very difficult, electro-chemical machining (ECM) is one of the more appropriate approach. However, micro holes fabricated using ECM can have different diameters at the entrances and exits and such tapering effect is not localized. In this work, a new ECM method named electro-chemical micro drilling (ECMD) for machining high quality straight micro holes in difficult-to-machine material was introduced, and the micro-spherical electrode fabricated by a hybrid technique combining micro-ECM with one pulse electro discharge (OPED) was used in ECMD process. Micro-spherical electrode and ultra short pulses (tens of nanosecond scale) were used to locally dissolve the area with the effect of voltage, pulse width and pulse frequency on the localization distance being studied. High quality micro holes with a diameter of 42 µm in a 70 µm thick nickel foil were drilled using micro-spherical electrode with a sphere diameter of 30 µm.

Abstract: Electrochemical discharge machining (ECDM), based on electrochemical machining (ECM) and electrodischarge machining (EDM), is an unconventional micro-machining technology. In this paper, with the use of water, the process of micro hole on ANSI 304 stainless steel machined by micro-ECDM with high speed rotating cathode is studied. The effects of machining conditions such as the cathode rotating speed and cathode diameter on the surface quality and accuracy of the shape are investigated. The results indicate that a relatively higher electrode rotating speed can improve the machining accuracy of the micro-holes and reduce the electrodes wear.

Abstract: This paper investigated the impact of area effect in the batch mode micro-EDM on shape accuracy and surface morphology of the machined microstructures, as well as electrode wear, using both the positive-type and the negative-type electrode arrays fabricated by the UV-LIGA process. Experimental results showed that ,with the increase of electrode-pair scale from Φ1mm, Φ2mm, Φ4mm to Φ8mm, the shape accuracy of the machined stainless steel microstructures increased, but the eroded microcavities of the machined area reduced in both the positive-type and the negative-type micro-EDM using the same electrical pulse parameters. It was also found that, with the same pulse energy and electrode-pair area, the electrode wear reduced as the electrode-couple area increased, and the wear ratio in the positive-type micro-EDM was larger than that in the negative-type micro-EDM.

Abstract: This paper introduces a method of machining free-form basis-NURBS curve into the field of micromachining. For achieving the optimization of the EMM (Electrochemical MicroMachining) process parameters, sets of experiments have been carried out to investigate the influence of some of the predominant electrochemical process parameters such as machining voltage, pulse on time, feed rate, and electrode peak shape on machining accuracy and quality. A complex shape with structures of several micrometers has been successfully obtained.

Abstract: In order to remove the reaction products generated from the interelectrode gap of the electrochemical micro-machining, an angle adjustable electrochemical micro-machining equipment has been developed, which consists of angle adjustment unit, feed system unit, etc. Small holes have been drilled on thin stainless steel 304 by using our developed equipment. The experimental results show that the adjusted cathode working angle and high speed of cathode rotation improves micro-ECM performance characteristics.

Abstract: High frequency acoustic agitation is known to improve mass transport in conventional electroplating and electroforming. To better understand the effect of ultrasonic agitation on microelectroforms with high height-to-width aspect recessed microstructure features, electroforming of Ni from a nickel sulfamate type electrolyte under the influence of high frequency ultrasound (33KHz) at different level of power intensity from 2W/cm2 to 16W/cm2 was investigated experimentally in this paper, and then optimum operating parameters were determined basing on surface topography. A number of microelectroforming experiments assisted with acoustic agitation were further carried out to demonstrate and revise the optimum process parameters and further some metal microdevices were produced. Experimental results showed that fewer drawbacks in the microelectroforms, such as nubbles, pits, blunt-edges, and collapses were observed in the microcomponents when sonication power 12W/cm2~14W/cm2 was drawn on. Microelectroforming with ultrasonic irradiation at appropriate power intensity was characterized by better surface morphology and better uniform filling behavior.