Electrochemical discharge machining (ECDM) is a machining method for inorganic insulators. In this repot, the relationship between applied voltage, which is a changeable condition during ECDM, and current waveforms was experimentally compared. The effect of the initial gap between a tool electrode and workpiece was also investigated. As the applied voltage was increased, lower frequency components of the current measured during ECDM of soda lime glass in NaCl solution were decreased. The initial gap did not affect the current waveforms. The mixture of long and short pulses accelerated removal at a low applied voltage.

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Demands for high precision machining of complicated shapes have recently increased with the miniaturization of mechanical and electronic products. Therefore, further development of fine wire electrical discharge machining (EDM) technology using a thin wire electrode has been also requested. However, the improvement in fine wire EDM performance using conventional wire electrodes seems to be limited only by optimizing discharge pulse conditions and gap control. Thus, it is essential to develop a new type of thin wire electrode for further improvement of the wire EDM performance. In this study, high zinc content brass (γ-phase brass) coated steel core wire as a new type wire electrode was trially made to improve the machining stability. In wire EDM, zinc content of wire surface would contribute to rapidly cool down the gap by the evaporation due to its low boiling point. However, the surface of γ-phase brass coated wire tends to become rough by its low-ductility in the wire drawing process. Thus, another type of the γ-phase brass coated wire with smoothed surface was also made by a finish drawing. The wire EDM characteristics using these wires were compared with those using conventional brass coated steel wire. Furthermore, the distribution of spark locations during process was evaluated by high-speed observation to investigate the influences of γ-phase brass and the surface roughness of wire.

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In current mechanical machining technology, it is not easy to form an internal space shape inside a metal workpiece through a small-diameter entrance hole. This is because it is necessary to insert a slender cutting tool with bending or curving function from the small entrance hole and to remove material in a direction different from the tool axis one under large machining force acting on the tool. On the other hand, the machining force acting on tool electrode is extremely small in electrical discharge machining (EDM). Therefore, it is highly expected that an internal space shape can be machined if an optimum electrode structure can be designed. This study proposes a new internal space machining method by EDM using a revolution ball electrode consisting of a vertical rotation rod, a tilting rod, and an electrode ball. The bending angle between the vertical rotation rod and the tilting one can be controlled by the rotation speed of the vertical rotation rod, and the electrode ball position can be changed. The experimental results show that this method has high possibility to create axially symmetric spatial shapes inside the metal.

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A curved-hole drilling by electrical discharge machining (EDM) using a suspended ball electrode composed of a metal ball and flexible thin foil has been developed, and it was clarified that curved-holes and bended-holes with various curving and bending angles into various workpiece materials could be machined by controlling the tilting angle of workpiece during the process. However, bended-hole with bending angle over 45° and curved-hole with drilling hole depth over 80 mm have not yet been tried so far. For further wide practical application of this method, the curved hole EDM drillings with large bending angle and with hole depth were experimentally investigated in this report. In EDM drilling of a straight hole into aluminum alloy using a electrode ball of 10 mm in diameter, the drilling performance was very stable. Bended-holes with large bending angle, such as right-angle (90°), could be accurately formed by using a foil-supporting jig. Additionally, various bended holes with large bending angles were suceeded by controlling the tilting angle of workpiece. Furthermore, when a suspended ball electrode with very long foil over 600mm was used for drilling deep curved-hole, a very deep curved-hole of 500 mm length with 16° curving angle was successfully drilled.

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Carbon fiber reinforced plastics (CFRP) are widely used in the aerospace and automotive industries because they have high specific strength. However, CFRP is a difficult-to-cut material, which causes high production costs. In this research, the electric discharge machining experiment was performed perpendicular to CFRP using the electric discharge machine Sodick K1C and several electrode wares tested. The CFRP work piece consists of unidirectional prepreg (Toray, T700SC) stacked in an orthogonal direction on each layer, sandwiched by plain weave prepreg (Toray, T300) layer. From this study, it was found that there is no effect on the machining time and surface roughness by the electrode materials, and the current value and the discharge pulse time are greatly affected.Also, it was found that the condition of a short circuit changes depending on the distance between electrodes and work piece, and it affects the diameter of the machined hole.

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The paper treats of the formability of the functional corrugated clad cup. Deep drawing, which is one of the pressing processes, is known as the most severe three-dimensional forming process. There are various types and shapes of products produced by this processing technology. In the present study, in order to enhance the functionality of the drawn cup, the corrugated clad cup with a corrugated structure on the cup side wall was formed by deep drawing. Since the side wall of the cup had a wave shape, the wave shape was reproduced by using a unique die in which steel balls were arranged without the gaps in the shoulder of the die. In the experiment, the materials were low carbon steel SPCC, stainless steel SUS304, and pure titanium JIS-TP340. In the deep drawing process, the round blank was employed and a flat sheet blank was formed into a circle by a punch. The laminated sheets were successfully drawn without the cracks. It was found that the corrugated clad cups were successfully formed by using the roller die.

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Boriding is widely used as one of the hardening methods of pure titanium. In this research, the influence of boriding temperatures of pure titanium by boriding were examined. It was revealed that the thickness of diffusion layer increased gradually with the temperature increasing. As a result of the examination, with the processing temperature increasing, the surface hardness was increased gradually. And the hardness of the diffusion layer became higher when the processing temperature at 1050°C and higher. In summary, when the processing temperature at 1050°C and higher, the boriding of pure titanium can improve the comprehensive properties.

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In recent years, the application of ceramic end mill has been studied for the purpose of improving the efficiency of end milling of difficult-to-cut materials such as Ni-base heat resistant alloys. However, although there are cases of application in simple shape and continuous cutting, there are few cases of application in groove shape and intermittent cutting.In this study, the relationship between the tool path and the tool edge condition was verified by the cutting test of the groove shape of Inconel 718 with a ceramic end mill. As a result, it was found that the damage state of the tool was greatly different depending on the tool path. In particular, the tool life was the best among the test conditions under the condition that the ramping process was applied to the axial cutting with a 4-flute tool.

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The purpose of this study is to obtain a turning performance of various types of diamond tool in cutting of TiAl alloy. TiAl alloys are difficult to cut because they have poor thermal conductivity and high strength in high-temp atmosphere. Generally, diamond tools with high thermal conductivity and high hardness are effective for titanium alloys. Cutting performance was evaluated using various diamond tools in the experiment. From the results obtained in this study, it is suggested that anti-wear or anti-failure performance of diamond tool in cutting of TiAl alloy is correlated with the TRS of the tool.

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Titanium alloys are widely used in aerospace applications due to their excellent material properties. Nevertheless the low machining speed and short tool life represent the high cost of machining titanium alloys. Laser assisted machining (LAM) has been developed to be an advanced technique to machine this kind of hard-to-machine material and to improve machinability. Most researches in this field are conducted to assess the effect of various cutting parameters to optimize cutting condition and maximum benefits of LAM. Therefore, the primary objective of this study is to evaluate the influence of laser power on the surface quality and tool life during LAM of Ti-6Al-4V alloys. The surface roughness was decreased with the application of LAM, while tool life was increased 1.4 times comparing to conventional machining (CM). A laser power between 20 and 40 W was best suited for LAM of titanium alloys at cutting speed of 100 m/min. Furthermore, a cutting temperature between 240 and 310 °C was proved to be optimal.

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Inconel 718 is known as a difficult-to-cut material because it has high strength and high corrosion resistance in high temperature range. As a means to improve the intractability of this Inconel 718, in the cutting process, high-power laser of kW class is irradiated near the cutting point. It has been reported that it can reduce the cutting force and extend the tool life. However, high power lasers are difficult to install at the production site because they have problems such as high cost. Thus, in this research, in turning of Inconel 718, the cutting force and the tool life were investigated about the cutting force and tool life by irradiating about 100 W low power laser near the cutting point. As a result, it was found that although there was no significant change in cutting resistance in carbide tools, changes such as chip division were observed even without using a high-power laser.

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This paper describes the effect of amplitude of longitudinal ultrasonic vibration on tightening miniature screw threads in terms of tightening torque, bearing surface friction torque and thread torque. Miniature screw threads of S1.4 are tightened with the ultrasonic vibration of 4 different amplitudes of 60 kHz longitudinal vibration. The experimental results indicate that the amplitude of 2.6μm reduces the tightening torque by 25%. In the case of the amplitude of 1.8μm, the largest depression of the contact surface of specimen was formed. These experimental results suggest that the amplitude of vibration should be optimized.

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When a three-dimensional shape such as mold is machined by NC machine tool, the quadrant glitch occurs around the motion direction changing point of the translational axes, which has a big influence on the quality of the machined surface. A lot of results of the study to improve the quality of the machined surface with a quadrant glitch by NC machine tool are reported until now. However, the study on the transcriptional characteristics to a machined surface of the quadrant glitch of the translational axes has not been yet investigated enough. In this study, for the purpose of the investigating the influence of a quadrant glitch to a machined surface, the transcriptional characteristics of a quadrant glitch to a machined surface were investigated by actual machining experiments.

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High machining accuracy is required for precision components of optical, aircraft and other various parts. In precision machining, thermal deformation of machine tool is one of main cause that deteriorates the machining accuracies. Accordingly, controlling temperature of the spindle and other components of the machine tool is significantly important to achieve desired machining accuracy. In general, forced fluid cooling is used for removing generated heat in the machine tool. It is desired to change appropriately the cooling conditions for the target component such as spindle according to heat generation that depends on the various machining conditions. However, conventional chiller for machine tools does not have appropriate temperature control resolution and response. In this paper, we propose a new method of fluid temperature control that achieves precise temperature control and better responsiveness. In this proposed method, temperature of cooling fluid is controlled by mixing cooling fluids that are different temperatures. Then, we develop temperature control system for machine tools depend on this method. Control performances of this system are evaluated experimentally and theoretically. Finally, further to improve control performance of this system, we investigate effectiveness of disturbance observer incorporated into this system.

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In order to achieve both high stiffness and light weight of the machine tool structure, ribs and partitions are installed into the main body structure such as columns and beds. However, evaluation of thermal characteristics combined with mechanical characteristics of the structural bodies has not been studied so far. Therefore, this study evaluates thermal and mechanical characteristics of various column structures by simulation with the finite element method. In addition to static and dynamic stiffness of various columns with ribs and partitions, thermal structural stability can be evaluated. The result confirmed that thermal stiffness of columns differs by arrangement of ribs or partitions even if columns have same mechanical stiffness, and thermal stiffness of the entire structure can be expressed by the sum of the thermal stiffness of the basic structure and each rib or partition.

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In recent years, the surface quality requirement in die and mold has become increasingly severe. In addition, die and mold that difficult to polish are increasing, and hence mirror finishing by cutting is required. In order to obtain mirror surface by cutting, it is necessary to reduce influence of tool non-repeatable run-out (NRRO) on machining surface. In this study, we confirmed effectiveness of a prototype excitation system that extracts NRRO component from measured tool run-out signal and reduce it using voice coil motor added to the spindle head.

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Demand for generating functional surface with micro texture to the large scale and complex structure has increased in industries. In order to meet such demand, it is important to develop a fast tool servo technology for milling process to generate fine pattern on freeform surface efficiently. This paper presents a newly developed machining system equipped with a fast tool servo driven by giant magnetostrictive element (GME) and its basic machining performance. The developed 3 axis machining system has aerostatic spindle equipped with the GME-driven tool servo mechanism and feed axes of a workpiece. Through actual machining experiments, the results confirmed that the developed system has capability to position a tool during milling process and can generate micro structure precisely.

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Several 3D printing technologies have been proposed for rapid prototyping or rapid manufacturing of CFRP. However, shell shape forming is difficult because of low adhesion strength between layers in 3D printing, and it cannot keep enough stiffness. Therefore, the authors focused on incremental forming, which enables shell shape forming from the sheet materials. In our previous studies, the rapid prototyping method using incremental forming for CRRTP has been proposed, and fundamental forming experiment has been carried out, and the formability of incremental forming under appropriate temperature conditions was demonstrated. However, Local heating is required to achieve high controllability. In the study, a fundamental experiment of the laser-assisted incremental forming method has been conducted.

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Directed Energy Deposition (DED), one of the metal additive manufacturing processes, can produce large-sized and complex-shaped parts using difficult-to-cut materials. From this aspect, DED starts to be used in airplane and turbine productions these days. DED is a process forming a melt pool on the deposition point by irradiating laser and supplying metal powder simultaneously. However, the cooling condition at deposition point drastically changes in DED because the exhaust heat depends on the shape and thermal property of deposit. Therefore, the quality of DED-produced part is difficult to keep stable because the bias of mechanical properties easily appears according to the deposition condition. In this research, the coolant supply system for DED was prepared, and the influence of temperature change on the mechanical properties was evaluated. Furthermore, a preferable cooling condition was experimentally identified to obtain a uniform mechanical property in the deposit through Vickers hardness measurement and metallurgical structure observation.

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Wire and arc-based additive manufacturing (WAAM) is a kind of the additive manufacturing process using the arc welding technology; where the molten metal made by the arc discharge is accumulated successively in this process. A plasma welding method was applied for the additive manufacturing using Ti-6Al-4V wire. A welding torch was attached to a 5-axis machining center and the WAAM process using Ti-6Al-4V was made possible by controlling the movement of X, Y, Z and C axes. During the WAAM process, Ti-6Al-4V should be protected from oxygen because Ti-6Al-4V easily react with oxygen. So, a local shield was used for protecting melting bead from oxygen. The shape of local shield was decided by flow analysis and process parameters for fabrication were revealed. In addition, it was shown that the fabricated object had enough mechanical properties compared with the same bulk material for Vickers hardness test.

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Weld-overlay cladding requires fabricating several layers to ensure a surface layer with a wire material in conformity with the standard because a molten material is diluted by a base material. In this study, we developed a novel method to ensure an undiluted surface layer with a wire material on a second layer of the fabricated object by TIG-MIG hybrid welding. A combination used was a stainless for TIG welding and Ni-based alloy for MIG welding. By the proposed method, a welding circumference of a stainless pipe was conducted, and the pipe was added with Ni-based surface layer. It provided good welding penetration and there was no defect. In addition, mechanical properties near the interface such as hardness and the distribution of Ni, Fe and Mo on the cross-section of the fabricated object were investigated. As a result, it was found that the mechanical properties of the manufactured alloy were comparable to those of a bulk material. Furthermore, Fe was uniformly distributed in the stainless layer, and Ni and Mo were uniformly distributed in the Ni-based layer. Ratios of the components in the surface layer were equivalent to the used wire material.

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In FDM technology, which is performed by extruding a material from a heated nozzle using an MIM material, generally uses a resin material as a binder. This process requires degreasing and sintering steps to remove a binder after molding. The degreasing process is carried out in a dedicated apparatus using an organic solvent. In this study, using agar as a binder, it was possible to carry out degreasing and sintering processes continuously in the same furnace. In this report, the effect of material mixing ratio of metal powder, agar, and water on the density and hardness of shapes was clarified.

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Powder Bed Fusion (PBF) is one of the process of Additive Manufacturing. In PBF process, 3D structure is built by repetition of selective melting and solidification of layered metal powder by laser. The melting and solidification process of PBF is depend on specification of metal powder. In this paper, the thermal conductivity of two types of metal powder which have different particle diameter range and bulk density was measured. In addition, the melting process of one-line building was visualized by the high-speed camera and the influence of thermal conductivity on the building characteristics was evaluated. As a result, the deposited metal powder with a high bulk density had high thermal conductivity. Many spatter particles and metallic jets were scattered from the metal powder including the fine particle powders. The thermal conductivity of metal powder also affected the building characteristics.

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In complex parts machining, workpiece shape and stiffness change greatly during a rough machining operation, and they induce workpiece displacement and vibration that strongly affect machining accuracy. However, it is difficult to automatically determine parameters of operation planning by using a commercial CAM software because there is a large number of combinations. Therefore, in order to improve the machining efficiency of complex parts, a determination method of workpiece shapes during a rough machining operation is proposed based on topology optimization. On the other hand, tool paths are not generated automatically to create the obtained workpiece shapes in the previous study. In this study, a generation method of tool paths is proposed by using the design variable to ensure workpiece stiffness during a rough machinig operation. By conducting a case study assuming complex parts machining, it is found that tool paths can be generated based on the design variable obtained in the calculation of topology optimization.

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Manufacturing industry tends to high-mix low-volume production in recent years. In the field of machining, it is strongly required to develop a computer aided process planning (CAPP) system to shorten the preparation time. On the other hand, it is expected that more efficient and rough machining would be achieved by 5-axis indexing that effectively utilizes the flexibility of the tool posture of 5-axis machine tools. However, it is difficult to automatically determine the tool postures to remove the unmachined area during a rough machining operation. Therefore, this study aims to establish a determination method of suitable tool postures according to the directions detected based on machining primitives that are divided from the removal area. According to the unmachined area, plural tool postures are allocated to the original machining primitive and respective machining feature is recognized for process planning. A case study is conducted to verify the usefulness of the proposed method to improve the efficiency of a rough machining operation.

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The appearance of various kinds of machine tools enables to manufacture complicated shapes and integrate manufacturing processes. However, the increasing of machine tool types, especially multi-axis control and multi-function machine tools forces heavy labor to select a suitable machine tool. Therefore, it is required to automate the machine tool selection to improve production efficiency. This study aims to automate the machine tool selection by evaluating and comparing machining processes based on form-generating motions. A system to recognize machining features considering the description of form-generating function of machine tools is developed as the first step in this study. In addition, process analysis is achieved depending on recognized machining features that the shapes are a hollow cylindrical shape or a solid cylindrical shape. Case studies are conducted to confirm the usefulness of the developed system. From the results, machining features are recognized based on the description of form-generating function and the results of process analysis are obtained successfully to support the machine tool selection.

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The cutter location data of 5-axis controlled machining can be easily generated by the intuitive operation of a cutting tool in a virtual space with a haptic device, which considers the collision between a cutting tool and a workpiece shape and the depth of cut into a target shape. However, the continuity of cutting points and tool postures may be disrupted by the vibration of the operating hand. In this report, the tool path generation method that is optimal for rough cutting is developed by smoothing cutting points and tool postures obtained thorough the haptic device.

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In this research, I will present a high precision grinding technique of cutting edge of punch. This method performs finish grinding process planning method by simultaneous three-axis control of a conical grindstones on a machining center. Cutting edges of punch are tools used to cut out thin-walled shapes, it is necessary to limit the thickness of the tip of the cutting edge to 10 [µm] or less and to suppress a surface roughness of cutting edge, because the thickness and the surface roughness affect the generation of chips and cutting quality at the time of material cutting. I try to apply to an irregularly shaped cutting edge of punch processing condition of a straight blade that the surface roughness of the edge is suppressed by carrying out truing and the surface roughness can be further suppressed by grinding by a path tilted along the edge. As a result, it became possible to generate cutting edges of punch with complicated shapes by processing condition and tool path.

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Smart manufacturing using IOT technologies such as collaboration with high-level production systems, feedback of machining information to upstream processes, and pre-verification is attracting attention. In this context, the construction methods of so-called digital twin machines and various applications are beginning to be discussed. However, the current situation is that the application is limited to scheduling in the shop floor and the whole factory. In this research, we propose a digital twin that realizes machining motion function of multi-axis machine tool in cyber space by multi-axis machine tool model and machining shape simulation. In addition, as an application example of digital twin, we propose an application system for process planning by real and virtual machining cases created by real machine tool and digital twin.

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In this study, we will improve production by reviewing the production line. In order to realize improvement, we will develop a system to decide the layout of assembly production line, with several workers involved. In this study, we define this system as System of Production-line-layout Decision by Chameleon-code and Genetic Algorithm (PDCG). PDCG decides a layout of production line using GA and work-flow-line acquired from Chameleon code and machine failure data. Specifically, PDCG calculates and evaluates the worker's walking time for repair of the machine failure generated in production line from the line layout operated by one worker per line. Then PDCG decides the good layout which operates multiple production lines with one worker. We compared the layout obtained by PDCG with parallel layout. As a result, PDCG layout reduced walking time by about 63 minutes from parallel layout. Therefore, PDCG is effective for layout arrangement in which one worker manages multiple production lines.

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In recent years, photovoltaic power generation has spread around world as the performance of solar panels has improved. Although, small islands such as Japan which does not have enough space to install solar panels desire to use of the exclusive economic zone. In this paper, we investigate the possibility of solar power generation under the sea water by demonstration experiments. In order to investigate the possibility of solar power generation under the sea water, preliminary experiments were conducted using a single crystal silicon solar panel. As a result, 1) The power generation efficiency does not decrease until the water depth reaches 200mm. 2) The power generation efficiency is greatly influenced by the water temperature. The lower the water temperature results the higher the power generation efficiency. 3) Electric power generation efficiency is not affected by salinity up to 5w%.

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Mechanical system has a lot of joints and each joint has coupling surfaces. The maximum fixing resistance of them is depending on static friction coefficient, and it effects static, kinetic and thermal characteristic strongly. There are many research regarding the static friction coefficient, however, they are not applicable for combination of the parameters of the coupling surfaces because of the problems of their measurement device. Therefore, in this paper, we developed new measurement device for static friction coefficient between fixed coupling surfaces which solves problems of the former devices. The new device enabled surface contact and uniform surface pressure by deploying the bearing unit with aligning function at loading part. It was confirmed that there's no moment force by generating the frictional force on same plane of the contact face of the specimen. Additional points were also checked that sampling rate is enough to catch the peak of the frictional force and there's no extra component force except load and frictional force. Finally, through verification test, the new measurement device proved that is able to evaluate the influence of surface roughness given to static friction coefficient.

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Using the electric field-assisted solid-state ion exchange method, metal ions were doped into a borosilicate glass surface. Especially when silver was used as a dopant material, a buried silver precipitation layer was formed in the ion-doped area by additional voltage application. For the industrial application of the precipitates to internal electrical circuits, it is necessary to control the shape of silver doped/precipitated area. In this study, we investigated the influence of shape/location of used electrodes on the shape of silver-doped area. When the upper and lower electrodes were located in opposite direction, the silver-doped area with uniform depth was formed. On the other hand, the inclined doped area was formed with diagonally located electrodes to the glass. This result shows the silver ions tend to move toward a neighboring cathode plate. In addition, it was suggested that the cathode plate played a role of outlet of sodium ions ejected from glass substrate.

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The interaction between nm-scale metal structures and light has the property which cause strong light absorption and electric field enhancement. This phenomena, called LSPR (Localized Surface Plasmon Resonance) is expected to be applied to various optical devices, for example biosensor and SERS substrate. To make optical device efficient, we apply a fabrication method of gold nanodot array combining nano plastic forming (NPF) and metal self-organization by annealing. In this research, we got various size gold nanodot array about 130~460nm in diameter and confirmed they caused interactions with visible light and near-infrared light. Finally, we measured optical properties of gold nanodot array and examined the possibility of application to optical device such as a biosensor or a SERS substrate.

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Recent years, artificial optical functional materials are collecting attention. However, it is necessary to produce huge number of metallic nanostructures of several 100 nm or less in order to realize such functional materials. In order to address this problem, the authors aim to develop an efficient nanofabrication process of metallic nanostructures utilizing nanoembossing technique. In this paper, the embossed height of nanostructures that can be formed on metal thin films by nanoembossing was examined from both experimental and numerical study. Experimentally, a diamond mold having nanohollows of various shapes and sizes was pressed onto thin gold films coated on quarts substrates. Analytically, a plane strain model was created, and analysis was conducted on various combinations of groove width and contact width of mold to derive a formula that enables to estimate the embossed height. As a result of experiment, it was found that the embossed heights depend on the position of hollows in the contact area of the mold. As a result of comparing the experiment and the analysis, it was found that the ratio of the embossed heights to the film thickness of the nanostructures arranged parallel to the outer side of the square mold show linearity to the analysis value. In addition, it was shown that the slope of the approximate straight lines vary depending on the film thickness, and it is suggested that the cause is the influence of the internal structure of the metal thin film and the adhesion between the substrate and the metal thin film.

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In order to improve the fuel economy of automobiles, the need for reducing the weight of vehicles has been drastically increased. By joining Al alloys which are light weight, high strength and excellent in productivity has attracted attention. In the previous research, we obtained a high strength joint which bonded in the N2 atmosphere because the oxide film on the surface of the Zn insert material was replaced and removed by using the Zn sheet subjected to the formate coating treatment. In this study, focusing on the mechanical destruction behavior of the superficial oxide film on the Al alloy side, the influence of the bonding surface roughness on the Al alloy side in the bonding in air was investigated. As a result, when the Al bonding surface was polished by SiC paper # 500, the bonding strength was the highest. This is considered to be suitable for mechanical destruction of the oxide film of Al and discharge of the liquid phase consisting of Zn and Al.

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Hydrothermal synthesis is a process that combines material synthesis driven by the reaction of aqueous solutions and the crystal growth at elevated temperature and pressure. Various materials and structures have been produced aiming at new sensors or actuators. However, the estimation of the structure or morphology after the synthesis is difficult because crystal growth and dissolution proceeds in parallel after indefinite nucleation. This study proposes an improved hydrothermal process to produce regular structures with controlled nucleation and crystal growth. First example is zinc oxide (ZnO) urchin-like structures. ZnO particles of φ100 nm were self-assembled on a substrate with dip coating method. Then, hydrothermal synthesis was carried out using these particles as nuclei. Urchin-like structures or hollow spheres were obtained. Second example is titanium dioxide (TiO₂) rods vertically aligned on a substrate. In this case, the substrate crystal structure is the key. Fluorine doped tin oxide (FTO) can be used not only for transparent electrode but for the special substrate for hydrothermal synthesis because the lattice constant of FTO is similar with that of TiO₂.

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In cutting of Ti-Alloys with extremely low thermal conductivity, the tool tip temperature rises significantly. Therefore, in high-speed cutting of Ti-Alloys, tool cooling using heat transfer by high pressure supply of water-soluble cutting fluid is carried out, but the cooling effect is small with respect to the supply amount. Therefore, in this research, we tried to suppress the heat generation during machining by utilizing the lubricating effect of the oil. In this test, high-speed milling with a very short cutting time realizes high-speed cutting of Ti-Alloys while securing the lubricating effect. And we confirmed the effectiveness of the lubricant by examining tool wear and cutting forces. In addition to the comparison based on the presence or absence of the lubricating oil, the comparison was also made based on the viscosity of the lubricating oil. As a result, when lubricating oil was used, it was confirmed that chipping and adhesion at the cutting edge were suppressed and the thrust force was also reduced. In addition, using a low viscosity oil agent maintained a better blade edge condition, suggested that a low viscosity oil agent with higher permeability exhibits more lubricating effect.

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Generally, in metalworking fluids including cutting oils, mineral oils are often used as base stocks. In addition, extreme pressure additives containing sulfur are blended to improve the cutting performance. Recently, in order to raise the flash point and to reduce the fire risk, there is an increasing demand for lubricants where esters having sufficiently high flash points, compared with those of mineral oils, are used as base stocks. However, little has been published regarding the effectiveness of the organo-sulur compounds in esters. In this study, sulfurized olefin and sulfurized ester in an ester base stock were evaluated based on both the cutting performance and the anti-seizure property. In the cutting performance evaluation, the tapping test results indicated that there was no significant difference between sulfurized olefin and sulfurized ester in ester, although the previous study suggested sulfurized ester were superior to sulfurized olefin in mineral oil. On the other hand, in the anti-seizure property evaluation, the results obtained by the Falex pin and vee block method demonstrated that the lubricating effects of those organo-sulfur compounds were depended on the type of the base stock, that is, mineral oil or ester.

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