Katsuhiko Sakai

Generation of three-dimensional micro structure using metal jet

In recent years, various micro machining processes have been developed to meet the demand for micro machines. However, the material is limited to silicon or plastics. In this study, the authors developed a method to form micro models by a metal jet. This method is similar to an ink jet printing system. A thin layer is first formed by molten metal drops ejected through a nozzle, and a second layer is formed on the first layer. The repetition of this process produces 3-dimensional models. The diameters of hemispherical metal dots adhered on a base plate were about 400 μm. To perform forming, a computer-controlled X-Y-Z stage was used to move the base plate based on 3-dimensional CAD data. Suitable conditions for the metal jet head such as actuating voltage, temperature of molten metal, ejecting frequency and so on were studied to perform accurate and stable forming, and some typical examples of 3-dimensional electric circuits and functionally gradient material were shown.

Study on Cutting Characteristics under a Nitrogen Atmosphere

In the existing circumstances, a lot of oil is used in the cutting process and almost all oil is finally incinerated. One of the problem is that dioxin may be produced when the oil is incinerated. Therefore, we have to make a new cutting process to reduce these oils. A ideal solution to this problem is dry cutting, but the tool life is probably shortened because of the lack of cooling factor. Without the cooling factor, tool temperature increases significantly. About this heat process, we can surmise that, there are two factors in it. One of the factors is frictional heat between tools and work, and the other factor is generation of heat by oxidation. Then, the cutting in nitrogen gas can control the generation of heat by oxidation and increase the tool life. However in nitrogen cutting, higher, the concentration of nitrogen, more, the adhesion occurs. In this study, we tried to solve the adhesive problems by changing the cutting condition and tool materials. As a result, we can increase tool life such that high speed dry cutting is possible, which has been infeasible. Furthermore, Nitrogen cutting has the possibility that oxygen concentration changes the cutting characteristics by the lubricating effect of metal oxide film. In this study, we also turned our attention to that and examine the concern with nitrogen concentration.

Generation of Three-dimensional Structures using Metal Jet. Application to Electric Circuit.

Recently the authors have proposed the metal jet technique which can make 3-dimensional micro structures made of metal drops. In this paper, solder jet was used to generate 2- and 3-dimensional electric circuit. Typical examples of 3-dimensional circuits are demonstrated and the electric resistivity and bonding strength between metal drops were measured. Further, some post processes are proposed to improve the resistivity of circuit made in the laboratory air.