Journal of The Japan Society of Electrical Machining Engineers

In recent years, multitasking machines have been attracting attention in the manufacturing industry from the viewpoints of shortening lead time and cost reduction. However, in electrical machining, a special machining fluid is used, which makes it difficult to combine this method with other methods. Therefore, it is considered that compounding is possible by circulating the electrolyte in the processing equipment and suppressing its scattering. In this study, we aim to combine other machining methods and electrochemical machining (ECM) by circulating the electrolyte in ECM. We devised three sealing methods and also confirmed the performance of each sealing method. In addition, by using the most suitable electrolyte sealing method, we observed the characteristics of ECM and the machining phenomenon by pressurizing the electrolyte.

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In this paper, we describe the characteristics of electrolytic finishing for internal walls of cooling channels circulated in molds produced by metal additive manufacturing (AM). The surface roughness Ra is comparatively large at approximately 50μm owing to the partial adhesion of unmelted metallic powder especially at the upper walls of internal cooling channels when the molds are produced by AM. This surface roughness reduces the corrosion fatigue strength of the molds. Therefore, in this study, we attempted to reduce the surface roughness of internal walls of cooling channels by electrolytic finishing, and a developed novel tool electrode that can machine the internal surfaces of curved channels of 5mm diameter. As a result, the surface roughness Ra was reduced from 50μm to 15μm even without preprocessing by chemical polishing. Moreover, when preprocessing was performed, the surface roughness Ra was reduced from 18μm to 5μm or less. Thus, from the measurement of the corrosion fatigue strength, we expect that the fatigue strength of the molds will be doubled when the surface roughness Ra is reduced to 5μm or less.

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