This paper presents an in situ process using a micro-tool in micro-electro-discharge-machining combined with co-deposited Ni–SiC composites to drill and finish micro-holes. During the machining process, a micro-tool is fabricated by wire electro-discharge grinding and electrodeposition. The experimental result shows that the suitable parameters obtained for fabricating micro-tools for Ni–SiC composite coatings are a current density of 7 A dm−2, positive ring hole diameter of 5 mm, SiC particle size of 4 µm, SiC particle concentration of 10 g l−1, rotational speed of 15 rpm and surfactant cetyltrimethylammonium bromide concentration of 150 ppm. When using this method, the micro-tool is provided with a smooth Ni layer, uniform particle distribution and suitable particle adhesion quantity. Then, circular micro-holes are machined in high nickel alloy. Scanning electron microscopy micrographs and atomic force microscopy measurements show that micro-grinding can improve the surface roughness from 1.47 µm Rmax to 0.462 µm Rmax.

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The purpose of this study was aimed at the evaluation of the mechanism of magnetic finishing with gel abrasive (MFGA), during which the performance of MFGA was compared to that of magnetic abrasive finishing (MAF). Of importance is that MFGA performs better than MAF based on the polishing-efficiency criterion. Silicone gels, however, are semisolid polymer gels with deforming properties that are temperature dependent, ultimately influencing significantly the polishing efficiency in MFGA. Therefore, taking as examples cylindrical rods which were polished using silicone gels with different plasticities to determine the corresponding temperatures of abrasive media in the working area, this study evaluated the MFGA mechanism to elucidate the properties of silicone gels and attain both the finished effect and effective gel abrasives in MFGA to produce a highly efficient polished surface. Next, circulating effects of abrasive media were identified to ensure the efficiency in MFGA and establish the relation between the concentrations of abrasive media and circulating effects in the working area. Experimental results show that silicone gels with low plasticity produce high temperature of abrasive media in MFGA; high temperature of abrasive medium makes excellent circulating effects in the working area, inducing high material removal and fine surface roughness.

Abstract:The aim of this paper is to improve the quality of surface roughness of precision molds, which is difficult to control in the traditional polishing technology, and to provide a kind of equipment which is simple and easy to operate in order to obtain a high precision in surface finishing and polishing. The combination of magnetic force polishing and electrophoretic polishing is mainly to combine the magnetic grinding mechanism with the electrophoretic deposition method to conduct finishing and polishing experiments. From the experimental results we can see that the combination of magnetic force and electrophoretic polishing can make the original roughness of the discharge surface of 1.7µm down to 0.08µm which is mirror effect after improving for 20 minutes. The experimental results show that the precision polishing combined with electrophoresis and magnetic grinding can effectively improve the surface roughness and therefore reduce technical and personnel training costs, shorten the production cycle time, and thus improve production efficiency. It can be concluded as a quite competitive technology in the industry.