Papers by Author: Di Zhu

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: Pinhole defect in the deposit is one of the ticklers which have not yet been solved fundamentally when micro-electroforming nickel into high-aspect-ratio (HAR) micro-molds. To obtain void-free micro-components, a new micro-electroforming technique, which was carried out under the complex circumstance of vacuum-degassing and temperature-gradient, was developed in this paper. Mechanisms of this micro-electroforming process were introduced using graphic and simulation methods. To investigate the feasibility of the exploited technique, a series of experiments were performed using special equipment developed by authors, followed by the evaluating of surface morphology of nickel micro-electroforms using a scanning electron microscope (SEM). Experimental results showed that, comparing with the conventional electroforming practices, a significant reduction in pinhole defects of the samples electroformed by the novel process was achieved.

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.