Papers by Author: Hui Chen

Abstract: Electrochemical micro machining is a critical micro machining technology. The purpose of this paper is to study the effect of ethylenediaminetetraacetic acid (EDTA) complex electrolyte in electrochemical micro machining (ECM) of stainless steel. The micro machining of stainless steel is difficult by electrochemical machining, especially in machining deep micro holes, because of an oxide layer formed on the surface. In this paper, ECM of stainless steel in EDTA complex electrolyte was researched. The influence of electrochemical machining parameters such as pulse duration, electrolyte composition to machine stainless steel was investigated. The results showed that EDTA can enhance the stability of electrochemical machining and the electrolyte is eco-friendly.

Abstract: In this paper an electrochemical drilling method for machning micro holes using a flatted electrode instead of the traditional cylindrical electrode is presented. Both electrochemical drilling processes, in which the cylindrical electrode and the flatted electrode were used respectively, were introduced under same machining conditions. The taper of the micro holes between entrance and exit was reduced and machining speed was improved when the flatted electrode was used compare with cylindrical electrode. The flow field simulation was taken out to investigate the reasons for micro holes electrochemical drilling has advantage in taper reducing and machining speed increasing with flatted electrodes.

Abstract: . The purpose of this paper is to study the application of electrochemical machining (ECM) technology for the fabrication of micro structures. The stray current corrosion, i.e. machining localization is a critical obstacle to micro fabrication for ECM. To machine micro structures by electrochemical machining ultra short voltage pulse is used. The effects of electrochemical machining parameters such as voltage, pulse duration, pulse frequency, and electrolyte composition on the machining accuracy were studied. In experiments, a micro hole was machined on stainless steel with cylindrical and square electrodes to investigate these effects.

Abstract: The designing of a micro turbine for micro gas turbine engine is presented in this paper. Micro power system is becoming more and more important for micro- and nano-scale system. The fast development of MEMS (Micro Electromechanical Systems) has strongly enhanced the application of new harder work materials. The fabrication of metallic 3D microstructures has been one of the most attractive topics of micro machining. Currently the basic materials of Micro-turbine Engineering were nonmetal materials such as SiC, most of them are 2D or quasi-3D structures. As a low cost, flexible, good repeatable machining process with negligible process forces, micro-EDM milling is well suited for freeform metallic micro structures. A three-dimensional micro turbine was fabricated by micro-EDM milling. A major problem in micro-EDM milling of complex 3D structure by using micro-electrode is the electrode wear. For reducing the impact of electrode wear, A new CAM system based on the UG software platform is developed in order to get good accuracy 2and higher efficiency. A simple tool path generation by CAD/CAM software and a general electrode wear compensation strategy is presented. The wear compensation can be apart from the design of CAD/CAM systems, so existing common CAD/CAM systems can be used to generate milling tool path with an unequal thickness lamination. And then post process for wear compensation and EDM milling can be done to modify tool path by adding wear compensation. The micro turbine blades of which the material is nickel alloy (GH4169) were successfully fabricated by using this strategy. The diameters of turbine are 2.8mm, and the height of each blade is 0.4mm.

Abstract: The purpose of this paper is to study electrochemical micro machining (ECM) technology on stainless steel. The micro machining of stainless steel is difficult by electrochemical machining, especially in machining deep micro holes, because of an oxide layer formed on the surface. To machining stainless steel, HF is usually used in electrolyte to destabilize the oxide layer. In this paper, ECM of stainless steel by applying short pulses in less toxic and corrosive electrolyte is research. The influence of electrochemical machining parameters such as voltage, current, electrolyte composition to machine stainless steel was investigated. The results showed that the oxide layer can be reduced by adding chloride and complex.

Abstract: Based on the principle of micro electrical discharge machining (EDM), a reversible machining method is proposed, which can achieve depositing or removing selectively metal material for the fabrication of micro structures. It is easy to transform the machining process from deposition to removal in one machining system. The characteristics of the deposited material show that the components of deposited material are almost the same as those of the tool electrode, and the metallurgical bonding has formed on the interface between the deposited material and the base. Moreover, the deposited material has well machinability in different micro EDM selective removal process, including micro EDM die-sinking and micro EDM milling. As a result, a micro square column with 0.1mm in side length, 0.88mm in height and a micro cylinder with 0.14mm in diameter, 1.18mm in height were fabricated by using the micro reversible EDM process.