Electrolyte jet machining is carried out by jetting the electrolyte from a nozzle toward the workpiece while applying voltage between the nozzle and workpiece. This machining method can selectively process metallic materials regardless of their hardness. Therefore, difficult-to-cut materials, such as a tungsten carbide (WC) rod, which is used as a fine tool, can be machined effectively if a suitable electrolyte and power supply are used. In this research, a method for removing the material on a rotating cylindrical workpiece by using the side surface of an electrolyte jet was proposed. The purpose of this study is to determine the optimal machining parameters, such as the rotating speed of the workpiece and the machining time for the shaping of a WC alloy rod by electrolyte jet machining. First, machining experiments were carried out without a nozzle scan to clarify the machining characteristics by changing the rotation speed of the workpiece. Then, shaping characteristics were investigated by changing the scanning speed of the nozzle.

Micro-electrochemical additive manufacturing (μECAM) is reverse of electrochemical micro-machining (μECM) which is used for selective and localized deposition of material on a substrate. It can be used to manufacture small sized parts or deposit functional metal coatings on conductive surfaces. As the process is contactless and generates negligible joule heating, the deposited material is free from heat affected zones and has low internal stresses. This work presents a free-flow jet micro-electrochemical additive manufacturing (FJECAM) process that deposits material through a continuous stream of electrolyte. FJECAM can deposit accurate μm to mm scale features without the need for expensive masking and complex meniscus control as used in traditional μECAM configurations. This facilitates rapid surface modifications, surface coatings and deposition of 2D-2.5D shapes with high accuracy. In this paper, the deposition mechanism of copper (Cu) on stainless steel substrate (S.S.) during FJECAM is investigated through the characterization of surface topography and analysis of process current. The micro-deposits with FJECAM at different voltages and scan rates were observed to be without porosities and a minimum surface roughness of 0.38 ± 0.02 μm was achieved at a material deposition rate (MDR) of 16.06 μg/s which is 20 times higher than the traditionally used meniscus-confined μECAM (MECAM) at the same process parameters.

Al-Cu alloy has been widely applied to automobile and aircraft products due to its high strength and low density. However, pitting corrosion easily occurs at intermetallic compounds (IMCs) of Al-Cu alloy. Thus, improvement in corrosion resistance of Al-Cu alloy by refinement of IMCs has been required. On the other hand, large-area EB with 60 mm in diameter can be used for melting the wide area of metal surface uniformly and instantly. Then, surface smoothing of mold steels can be performed efficiently. In addition, re-solidified layer with fine microstructures can be formed on the metal surface after the EB irradiation. It is highly expected that IMCs on Al-Cu alloy surface may be refined in re-solidified layer produced by the EB irradiation. In this study, the possibility for refinement of IMCs on Al-Cu alloy surface by large-area EB irradiation was investigated. Then, improvement in corrosion resistance of Al-Cu alloy surface was proposed.

When machining deep holes with a high aspect ratio on high-hardness materials, small-hole electrical discharge machining (EDM) is often used. In small-hole EDM, it is empirically known that the machining speed decreases as the machining hole becomes deeper. Hence, it is assumed that the debris stagnates and machining becomes unstable. Therefore, we have found the effect of suppressing the decrease in machining speed by using the grooved electrode. However, at that time, there was a problem because it was a self-made groove machining. Because it was formed by draw-cutting, the groove depth was not uniform and burrs were formed groove edge. In this report, the effect of a custom-made cross-sectional shape electrode using mass production equipment was investigated. Furthermore, it was clarified that the machining fluid ejection pressure affects the machining characteristics even when a normal pipe electrode is used.

The state where the solid layer exists on the liquid, was simulated by placing a thin sheet of solid metal on the liquid one, and laser irradiation experiment was conducted by using the simulated setup. Moreover, thermal fluid analysis was performed to understand the detail of drilling phenomena during the laser irradiation for the solid layer on the liquid. The high-speed observation revealed the time when the penetration hole was formed for the solid metal, and the intensity of reflected laser from the specimen changed just after the formation of penetration hole for solid metal on liquid one. The thermal fluid analysis indicated that the specific change of reflected laser intensity related to the detection of liquid surface. It was suggested that the exposed liquid surface under the solid layer could be detected by measuring the specific change of reflected laser intensity.