In order to automate and reduce the number of setups, a rotary table is added on a 3-axis machining center to increase the number of multi-axis machine tools. While the accuracy of the rotary table has been improved, the influence of the structure errors on the machining accuracy is too huge. The degree of parallelism and coaxiality between the three translational axes and the rotation axis of the rotary table affect to a serious problem of machining accuracy. In this research, the effect of structure errors of the rotary table on the machining accuracy is mathematically analyzed by FormShape-Function theory. Machining errors of cylindrical processing are expressed with structure errors in these series of simulations.

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The machining accuracy of the machine tool is not maintained constant level due to the thermal deformation of its component parts. To prevent the change in dimensional accuracy, it is important to prevent the heat transfer from the heat source. In this study, the thermal deformation of the CNC lathe machine caused by the heat generation from the spindle was analyzed. The analyzed thermal deformation was agreed with the measured result. By using the analyzed results, the oil that cooling the spindle was rapidly cooled to remove the heat generated from the spindle. It was confirmed that the change in the relative distance between the tool and the workpiece, that affected the dimensional accuracy of the machined workpiece directly, was reduced successfully by cooling the oil.

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In general, it is known that heat is a major cause of the dimensional inaccuracy of machine tools. In this research, we focused on the relation between a temperature distribution on a whole machining center and resultant displacement at a tool tip. We modeled an actual horizontal machining center for simulation and investigated the temperature of each part of the structure and the displacement of a tool tip by unsteady simulation, and showed the validity of the analytical model. We, then, investigated the relationship between the number of temperature sensors and the estimation error of resultant displacement at a tool tip by utilizing the simulation, and also the thermal influence of the cutting fluid hitting the structure. Finally, we confirmed that the influence of cutting fluid on the estimation error of the resultant displacement at a tool tip can be reduced as the number of sensors increases and we showed the number of temperature sensors for stable thermal displacement compensation despite the influence of the cutting fluid.

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During the cutting operations, it is expected that the vibration characteristics of the entire machine tool are influenced by the process damping and contacting stiffness due to the contact between the tool and the workpiece. In this study, excitation tests were carried out by using the motor torque command in the feed drive system. The frequency characteristics of the machine tool during the cutting operations were measured in both of with and without cutting operations and the influence of the contact between the tool and workpieces is investigated based on the changing of the frequency responses. As a result, it is confirmed that the natural frequency slightly increased during processing and the vibration amplitude decreased due to the contact. In addition, the influence of the contact between the tool and workpiece was quantitatively evaluated as the stiffness and damping coefficients by identifying the values through matching the measured and simulated frequency responses. The time domain coupled simulation between the machine tool dynamics and cutting force with the contacting effect are also carried out. As the results of the simulations, it is confirmed that the contacting stiffness and process damping have an effect to suppress the chatter during the cutting operations.

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In this research, a contactless loading device that can excite a rotating spindle was utilized to investigate the vibration of a spindle system. The vibration caused by an intermittent excitation force to a dummy tool attached to the spindle of a vertical three-axis machining center of a constant pressure preload type under the influence of the spindle rotation was investigated. It was observed that when the excitation force fluctuates intermittently due to the runout of the spindle, sideband waves occur. It was found that forced excitation is caused not only by the excitation frequency but also by the sideband waves.

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The intelligent system, in which machine tools autonomously monitor and optimize processes, has been attracted. In particular, autonomous suppression of chatter vibration, which hinders high efficient machining, is important, and the spindle speed variation (SSV) is an effective method. While SSV can be realized without additional equipment, its optimal design method has not been established. In this study, the optimal design of the SSV is proposed from the viewpoint of minimization of chatter-vibration energy based on the modulation index. The modulation index is introduced from the analogy with frequency modulation (FM) in radio engineering, and the proposed design methodology requires only the chatter frequency and spindle speed information. The proposed method was validated by a series of boring tests.

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In the NC moving table, especially in the case of reversal motion such as the circular are interpolation motion, the thrust force due to table driving torque becomes smaller than the frictional force generated on the sliding surface, the NC moving table stops, and the motion accuracy deteriorates. In this research, we measure the rotational force, which is the torque component of the AC servomotor in the NC moving table, and the radial force calculated from the drive current value, which is the field component to clarify the motion characteristics. Furthermore, based on the clarified motion characteristics, we devise a compensation method using the motor drive current value of the torque component to improve the reversal motion. Also the position of the NC moving table is measured using a rotary encoder attached to an AC servomotor and a linear encoder attached on the linear guide. From these results, we propose a torque compensation method of the NC moving table.

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This study aims to manufacture new desktop type 5-axis NC precision grinder for bioceramics artificial knee joint. The table-on-table type 5-axis grinder has been designed and manufactured. The specific axis arrangement have been three linear axis on the tool side and two axis on the workpiece side. Designing of the grinder were carried out using finite element method analysis and the grinder was prototyped. Performance evaluation tests were carried out for linear axis such as a static stiffness test, a straightness error motion test and a positioning accuracy test. Static stiffness of prototype was under 1 µm. Straight error motions of Z-axis were 1.59 µm in X-direction and 1.56 µm in Y-direction, respectively. Additionally, positioning accuracy of Z-axis shows less than 3.00 µm. From these results, There are no problems around Z-axis of the new grinder. However, error motion and positioning accuracy of X and Y linear axis were insufficient and future study.

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For aiming at deposition efficiency improvement of directed energy deposition (DED) type additive manufacturing operations, measurement and correction method of the head nozzle height was proposed. In the method, a melt pool formed on the deposited surface is monitored using a camera which is mounted offset to the laser nozzle. When the melt pool height position has been moved from the ideal position due to excessive or under deposition, the melt pool position shot on an image of the camera is also moved. Based on the triangulation method, the head nozzle height which is the distance between the head nozzle and melt pool has been measured from the displacement of melt pool position on the image. Using the proposed method, a thin wall shape consisting of 40 layers was deposited by measuring the laser nozzle height for every four layers and correcting the nozzle position for the next layer. Compared with the deposition result without correction, improvement of the deposition accuracy and powder efficiency using the method has been confirmed.

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In recent years, a demand of the high quality cutting surface of press die represented by a car is increased for shortening of polishing time. Cutting surface quality is strongly affected by tool path quality, and disturbance of NC data causes deterioration of cutting surface. However, it is difficult to judge tool path quality in advance and evaluation method becomes a problem. Various methods have been proposed in the past. The conventional method is to calculate and visualize the disturbance of NC data. However, with the conventional method, it is difficult to accurately analyze the influence on the cutting surface quality. Therefore, we have proposed a method of quantifying the quality of the tool path based on the information of the cutting conditions and the desired cutting surface quality. In this paper, report investigation of the method which quantify of tool path and predict of cutting surface condition to realize high quality cutting surface before cutting.

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Chatter vibration in cutting induces tool damage, large machining error, and deterioration of surface finish. The cutting conditions should be determined for the stable cutting process. The vibration analysis requires the modal parameters in the vibration model. Therefore, the modal parameters should be identified to predict the stability chart. In milling, the modal parameters might change corresponding to the tool-workpiece contact depending on the cutting thickness during a ration of the cutter. This study discusses the change in the modal parameters in milling. The impulse response tests were conducted with measuring the cutting force. The changes in the modal parameters were compared for the feed rates and the feed directions.

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Recently, manufacturing innovation have advanced all over the world by IoT and digital technology. Processing condition monitoring is attracting attention as an one of the most important technology. Research on processing monitoring has been conducted for many years. Various methods have also been proposed for monitoring of milling process. Semiconductor strain sensor is used in this study because it is inexpensive and highly sensitive. This paper aim to monitor of milling process using semiconductor strain sensor. In the first experiment, the strain of the clamping jig of the work material due to cutting force was measured by semiconductor strain sensor. In a second experiment, the strain on the thin part of the work material during micro end milling was measured by a sensor. The strain caused by periodically changing cutting force was successfully measured with high time resolution in each experiment.

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The propose of this study is to investigate the relation between tool flank wear and thermal dissipation on tool flank face. Tool flank wear and cutting temperature in dry cutting of Inconel 718 were analyzed. The temperature in the tool was measured by a sensor placed at the bottom face of the tool. The temperature field in the tool was estimated by using the inverse heat conduction method. The results show that there is linear relation between the tool flank wear and the measured temperature at the bottom face of the insert. Based on this result, the temperatures on tool rake face and on tool flank face were estimated. It is confirmed that tool flank wear plays a great role on the temperature rise and thermal dissipation on tool flank face.

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Residual stress in machining process affects the shape accuracy and the life of the product to be manufactured. Therefore, residual stress should be controlled to achieve the high quality of the product in the machining operation. This study discusses residual stress in milling in terms of the cutting force. The milling process in finishing surface consists of ploughing and cutting manners. The cutting tests were conducted to measure the cutting forces in up-cut milling with changing the feed rate. The minimum chip thicknesses were estimated at the change in the cutting force around the edge engagement process. Then, the resultant cutting forces and its directions in finishing a surface were determined to estimate the loading condition onto the workpiece surface. Residual stresses were measured in X-Ray measurement based on the principle of cos α scheme. Residual stresses are associated with the resultant cutting force and the cutting force direction.

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Cutting fluid has an influence on tool life in cutting in terms of lubrication and cooling. This study compares the cutting processes in milling of 0.45% carbon steel under dry and using 3 kinds of lubrications. The cutting force in dry is less than those of cuttings with lubrications due to thermal softening of material under high cutting temperatures. The dynamic component in milling with FGM408PR is different from those of millings in dry, with EC50T3 and Synthetic#880 due to the change in chip formation. The flank wear rates of bottom edges in milling with FGM408PR are lowest compared to the other conditions. In milling with FGM408PR, the burnt area on the flank face was not observed due to well penetration of the cutting fluid.

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Titanium alloy has excellent characteristics such as a light weight, high strength, high specific strength alloy with excellent corrosion resistance and biocompatibility, and is mainly used in the aerospace and medical fields. However, titanium alloys are known as difficult-to-cut materials because of their low thermal conductivity and their high chemical activity. Therefore, although it is common to use a large amount of cutting fluid agent at the production site, it is desirable to reduce the amount used in terms of cost increase and environmental impact. Therefore, in this research, the effectiveness of gas-assisted cutting of titanium alloy was experimentally examined by carrying out cutting tool wear tests and two-dimensional cutting experiments using nitrogen gas that can be expected to suppress oxidation heat generation. As a result, it was found that the tool wear was reduced at a cutting speed of 150 m / min or more and the oxidation reaction of tool rake surface was reduced by the EPMA in the nitrogen blow cutting.

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The propose of this study is to investigate the effect of built-up layer (BUL) on the tool flank wear rate and give the optimal cutting speed in cutting of difficult-to-cut material. Tool flank wear rate, machining efficiency and machining cost in cutting of Inconel 718 and Ti-6Al-4V with uncoated cemented carbide tools were analyzed. The results show that BUL has the tool protective effect and it can decrease tool flank wear rate. It is also confirmed that there is an exponential relationship between tool flank wear rate and cutting speed when cutting temperature is above 800℃. From the viewpoint of machining efficiency and machining cost, it can be concluded that the optimal cutting speed for utilizing BUL is 30 m/min for dry cutting Inconel 718, and 50 m/min for dry cutting Ti-6Al-4V when feed rate is 0.1 mm/rev.

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The turning of cemented tungsten carbide micropins was carried out using polycrystalline diamond micro turning tools and a microturning device. Fundamental cutting properties, which had not been previously reported in detail, were investigated. The cutting force increased with increasing cutting speed but did not show a clear relationship with the feed per revolution. The tool wear increased with increasing cutting speed and depth of cut, and saturated when the depth cut further increased.

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Cemented carbide (WC-Co) tools are widely used in industry as cutting tools. As a binder phase, cobalt has excellent wettability against tungsten carbide (WC), which makes the cemented carbide have very high transverse rupture strength. However, cobalt is rare metal, which is normally imported from a single country, and is concerned about having adverse effects on the environment and human health. It is becoming great importance that the development of novel tools and tool materials by using common metals of non-toxicity. As an alternative material of WC-Co, WC-FeAl of cobalt-free cemented carbide in which iron aluminide as intermetallic compound is used as binder material of WC powders has been proposed. In this research, we conducted machining tests of steel (S45C) by using commercial WC-Co tools and WC-FeAl tools manufactured by different sintering techniques (vacuum sintering or pulse current sintering), and cutting characteristics were compared. It was found that the vacuum sintered WC-FeAl tools were inferior in wear resistance to the WC-Co tools but excellent in adhesion resistance. The pulse current sintered WC-FeAl tools were excellent in adhesion resistance as vacuum sintered WC-FeAl tools. However, those tools had lower cutting resistance and finished surface roughness than the WC-Co tools and vacuum sintered WC-FeAl tools. Furthermore, the tool wear progressed in the pulsed current sintering WC-FeAl tools was larger than that of the vacuum sintering WC-FeAl tools.

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Recently, fields such as IoT, Industry 4.0 are eliciting significant attention. In cutting process, tool breakage detection and wear monitoring techniques are important to optimize tool change timing. Generally, in production sites, which is a method to manage tools, the replacement timing is often managed based on certain pre-determined period of time or number of workpieces finished. Thus, the tools are replaced in much shorter period than their actual service time, thereby increasing the tool costs. In particular, in cutting of a high hardness material using a diamond tool, it is important to monitor the damage state of the tool from the viewpoint of processing cost and processing accuracy. From this, in this study, a semiconductor strain sensor developed for IoT technologies was applied to cutting of cemented carbide by using PCD tool with the aim of developing the low-cost and high-sensitivity tool wear detection technology. As a result, it was found that the cutting force can be measured, and the increasing of the cutting force due to tool wear during cutting can be detected.

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Micro cutting technology is one of the important methods to fabricate micro-sized precision components in the semiconductor, electronics, and electro-mechanics industries. However, PEEK, which is a thermoplastic resin, has a problem that the hole accuracy is lowered due to the cutting heat. This paper describes drilling experiments with cooling on workpiece by cold air. As a result, it was found that cooling the workpiece is effective to suppressing the cutting heat and improve hole accuracy. Within the experimental conditions, the combination of non-step drilling and cooling enables high-precision drilling with approximately the same accuracy as step drilling.

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In this research, we have examined turn-milling, which has been attracting attention in recent years, using a multi-tasking machine. Turn-milling is a machining method in which cutting is performed while rotating a tool and a workpiece together. The experiment used a multi-tasking machine originally developed in the laboratory. The combined processing machine is constituted by four axes including a major axis in a vertical. In order to perform turn milling, processing experiments were performed at 1000 rpm for the main shaft and 130 rpm for the C-axis. The Y-axis feed rate was divided into six steps of 3, 6, 12, 24, 48 and 96 mm / min. Basically, the machining surface became rougher as the Y-axis feed rate increased. Moreover, when the linear motion axis and the rotation axis were compared, it turned out that a big load is applied to the rotation axis. By adding these, it is possible to perform high productivity turn mill processing.

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Recently, data acquisition and utilization techniques in production site such as IOT and industry 4.0 have attracted attention. In the drilling process, in order to avoid the breakage of the tool and the decrease in the processing accuracy due to the progress of the tool wear, it is required to establish the monitoring technology of the processing state during the cutting process that can be used at the production site. From this, in this research, a semiconductor strain sensor developed for IOT applications was attached to the surface of the drill, and measured the strain generated in the drilling process by the cutting force in NC lathe and attempted to monitor the machining condition of the drill during machining. As a result, it was possible to detect the strain of the tool during drilling without reducing the rigidity of the tool using a strain sensor which is easy to install.

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Cutting force characteristics were measured in cutting of a cross-ply carbon fiber reinforced plastic with a flat drill. Because the cutting is performed in a glass fiber, a carbon fiber or a bonding effect layer, the cutting force in each layer can be decomposed at the depth of cut. The effect of the cutting speed on the cutting force is evaluated at spindle speeds of 500 and 1000 rpm. The cutting force decreases when the cutting speed becomes high. The thickness of bonding effect layer is also estimated by the change in the thrust and torque. The cutting force in the carbon fiber layer gradually decrease around 0.02 mm from the bonding effect layer. In the presenting approach, the CFRP characteristics are evaluated quantitatively in terms of the cutting force.

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Generally, in ball end milling, it is effective to perform cutting by give tool tilt angle in order to obtain the cutting speed at the cutting point. However, because the micro-ball end mill has low tool rigidity, it is thought that tool deflection increases when the tool tilt angle is given, and processing accuracy decreases. From this fact, in this research, the effect of cutting with tool tilt angle in micro-ball end milling on the cutting characteristics were investigated. As a result, it was clarified that the cutting accuracy decreased in the cutting given the tool tilt angle in micro-ball end milling, and the cause was examined.

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In this study a new method of gear cutting is proposed. The principle of involute gear generation is as follows: the rack cutter moves in a reciprocatory manner and feeds to the tangential direction of the gear. In the proposed method, a taper endmill is used as the cutter, and the rotating cutter feeds in both the axial and tangential directions of the work gear. By using only a taper endmill, the machining of gears with various specifications including the module, number of teeth, pressure angle, and addendum modification coefficient can be realized. The commonly used gear-cutting method is that of hobbing or gear shaping. In these methods, dedicated tools such as a hob or pinion cutter are used; with them, only gears with a predetermined module and pressure angle are machined. In other words, when gears with different modules or pressure angles are machined, changing the tool is necessary. A formed tool is used as a gear-cutting method that employs an end mill. However, this tool can only machine a predetermined module, pressure angle, and number of teeth. The most important feature of the proposed gear-cutting method is that no restrictions are placed on the gear specifications. In this study, the geometric mechanism of an involute gear cutting using a taper end mill is described. An example of actual machining with a 5-axis machining center or a general-purpose milling machine is also shown, and the utility of the new method is discussed.

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In pathological diagnosis, it is necessary that the tumors are picked out by an operation, embedded in paraffin and sliced in thickness of around 2~5µm to prepare the slide glass. This slicing process is one of the important technologies that affect the accuracy of diagnosis. In this report, the mechanism of a micro slicing process of paraffin blocks was studied. As the temperature of paraffin blocks decrease, cutting force increases. Also, it doesn’t become zero where the setting depth of cut is zero due to tool edge roundness, and the model considering it was made.

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When estimating the effect of elastic deformation of a workpiece generated during machining on machining errors in machining of low rigidity objects, it is necessary to continuously carry out finite element analysis in the shape in the middle of machining and increase in calculation time becomes a problem. Then, in this study, was attempted to drastically reduce processing time by forming a data set obtained by making processing conditions and displacement distribution information after processing to two-dimensional image information, to develop a method guessing displacement distribution by machine learning. In this paper, we explain the results obtained for the shape of the blade.

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In recent cutting processes, 5-axis controlled machine tool has become essential as the shape of the work becomes complicated, and high efficiency by short-time machining under high feed conditions is required. However, in a machining plan based on a CAM system aiming to avoid interference, there is a problem that the actual feed speed does not reach the command value and the machining time becomes longer than expected. In this report, in machines with a trunnion stage type configuration, attention is paid to the jerk value of the turning axis, and propose the tool posture planning that restrain machining speed decrease by correction command value of turning axis.

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Laser hardening is not practically applied for thin workpieces due to difficulty of quick cooling. In this report, steel foils are successfully hardened by laser irradiation through fixing them on an aluminum base. A laser mark formed by a single laser shot shows circular hardened area and dimpled profile. Dot and space patterning by laser scanning sometimes shows braking of laser marks. This might be caused by laser deformation near preliminary hardened area.

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In the case of machining workpieces, the generation of burrs is unavoidable. Leaving the burrs on workpieces as they are will cause many problems, thus the deburring process is required. Deburring requires exclusive tools, which are not suited for removing burrs in narrow places. Laser machining is noncontact process thus it does not cause the deformation of workpiece and wearing of tools. Especially, fiber laser beam can be transmitted by using optical fibers so that it is easy to handle. The purpose of this study is to clarify the processing condition for achieving desired chamfering width with fiber laser. A series of experiments were performed by providing fiber laser beam to S50C block’s right angle edge. In the experiments, the beam diameter, the laser power and the processing speed were changed. Experimental results confirmed that defocused fiber laser could apply to chamfering ferrous materials. In addition, the results confirmed that the chamfering width could be controlled by changing processing parameters as the input energy per unit time and unit volume are kept at a constant. Furthermore, the burrs on right angle edge could be removed by fiber laser, and the shape of deburred edge becomes rounded.

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Carbon fiber reinforced plastics (CFRP) have been rapidly applied to many industrial fields including car manufacturing and aircraft manufacturing, because CFRP have excellent characteristics such as high mechanical strength and lightweight compared to other materials. However, it is difficult to deform CFRP sheet precisely due to composite materials. On the other hand, laser forming can deform materials by thermal stress without tools and dies, which would fabricate CFRP precisely. Therefore, the laser forming of carbon fiber reinforced thermoplastics (CFRTP) was experimentally investigated in order to apply CFRTP to precision products. Relationships between laser processing conditions and laser forming characteristics were discussed by line scanning of CO₂ laser beam on the CFRTP sheets. The measurement of processing temperature on the sheets revealed that CFRTP sheet was deformed by the thermal stress less than 225 ℃ as melting point of matrix. It was also found that bending angle increased with increasing overlap rate of pulsed laser beam.

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In thermal stress cleaving with laser, the substrates of brittle material are divided by crack propagation due to the thermal stress. Therefore, distribution of the stress is essential and should be controlled properly for high accuracy of process, but boundary conditions and unexpected disturbances sometimes cause asymmetry of the distribution. This paper concerns a photoelastic observation technique to investigate the asymmetry of thermal stress distribution, which provides the isoclinic fringe pattern and the isochromatic fringe pattern around the crack propagating in the laser cleaving process for brittle material substrates. The technique can visualize the asymmetry of the distribution and some results are reported in this paper for transparent substrates.

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Currently, the grind processing with a grindstone is commonly used for the removal processing of brittle materials including glass. However, this way is a direct contact processing by a grindstone. Therefore, it is difficult to process without micro cracks in the processing plane of glass. On the other hand, when a CO₂ laser was scanned on the glass surface under certain conditions, there is a phenomenon that the mirror surface groove and the curled glass fragment were generated on the glass surface. Therefore, the purpose of our study is to clarify the mechanism of occurrence of this phenomenon in other to develop non-contact processing technology by laser with high removal efficiency. For that purpose, we experiment with a groove processing under the various conditions for slicing processing condition. Then, the stress intensity factor at the processing depth obtained the experiment was conducted by FEM, and the crack opening region was considered.

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Microchannels on the polymer or glass substrate are generally formed by the microfabrication technology such as the semiconductor manufacturing technology. Although control of the shape is important for the microchannel formation, many processes are required to form the microchannels and it is difficult to control the shape on the semiconductor manufacturing technology. Thus, the microchannel formation on a quartz glass substrate by using a CO₂ laser were carried out. Then, relationships between microchannel shapes and laser processing conditions such as laser power, laser scanning speed and defocus amount were experimentally investigated. As a result, wide range of the microchannel shapes with the width of 150 - 400 µm and the depth of 100 - 1000 µm could be obtained by the CO₂ laser processing. Moreover, a microchannel shape with about 190 µm width and 250 µm depth formed by the laser processing enabled flow of pure water. Therefore, it was revealed that various shapes of the microchannels on the quartz glass substrates could be formed by the CO₂ laser, and the laser processing has possibilities for the generation of new microfluidic devices.

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The authors have been proposed metal sphere manipulation in glass by laser illumination. The metal sphere was implanted into a glass when the laser was illuminated to the metal foil through the glass. The metal sphere precipitated metal particles in silica glass. The metal sphere moved gathering metal particles with low power density of laser. This phenomenon could be used for removing impurities in glass. In this paper, we report the result that metal spheres absorbed same and different element metal particles. First, the metal sphere gathered metal particles as for same ingredient. As a result, the metal particles were gathered by metal sphere. Second iron sphere moved near by nichrome particles. As a result, the iron sphere gathered nichrome particles.

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The purpose of this research is to apply high efficiency microfabrication with low fluence by near infrared femtosecond laser by applying carbon film to synthetic quartz. In order to examine the effectiveness of the proposed method, a single pulse was irradiated on synthetic quartz coated with C film and synthetic quartz not coated. By applying the C film, the damage threshold of synthetic quartz decreased by 64%. In order to investigate the excitation effect in the proposed method, double pulse processing was performed on synthetic quartz coated with carbon film and synthetic quartz not coated. In double pulse processing, one laser pulse is used for the material of excitation and another pulse is used for processing. The damage threshold increased by laser pulse irradiation as pulse interval increased. As a result of this, one can see that excitation effect that converges over time has occurred. The convergence of the excitation effect of synthetic quartz coated with C film was different from that of synthetic quartz not coated. As a result of this, one can see that the excitation effect of quartz coated with C film is generated by ablation of the C film.

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Laser irradiation of yttria-stabilized zirconia (YSZ) was performed by ultrashort pulses to investigate the possibility for multiscale surface patterning. The fundamental characteristics of microgrooving and nanoscale periodic structure formation were investigated by the picosecond pulsed fiber laser (1030 nm, 100 kHz). It was found that the laser-induced periodic surface structure (LIPSS) formed inside microgrooves by increasing the number of line irradiations (10 irradiations) and over a large surface area more clearly under low scanning speed (1.0 mm/s). Furthermore, we evaluated the thermally induced phase transformation of YSZ from tetragonal to monoclinic phase. Monoclinic ratio was calculated by using micro Laser Raman spectrometer and it could be restrained by reducing the laser power or the number of irradiations. In addition, contact angle of water droplets on YSZ surface was measured and it was found that generation of LIPSS improved the surface hydrophilicity of YSZ. These results demonstrate the possibility of creating zirconia hybrid patterns with high functionality which may expand the applications of YSZ in industry.

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In this research, a surface texturing technique is applied on fine ceramic parts. An objective of this research is a technology development to achieve high-efficient flow of a solid-liquid two-phase flow in small gap between the parts. The solid-liquid two-phase flow has small solid particles of micrometers order in diameter in the liquid. As a surface texturing method, a laser was applied as a texturing tool because the laser processing independent on the strength of the material and the small laser spot is suitable to complete fine texturing on the fine ceramic parts. In the present paper, fundamental examination under various laser conditions was carried out. The effects of laser irradiation conditions on processing shape and size were investigated.

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A general-purpose three-dimensional thermohydraulics computational science numerical simulation code SPLICE was applied to laser welding processes for different kinds of materials to understand the phenomenological welding and solidifying mechanisms of both the materials. The SPLICE code was developed at JAEA (Japan Atomic Energy Agency) and designed to deal with gas-liquid-solid consolidated incompressible viscous flows with a phase change process in various laser applications, such as welding, piercing, drilling, cutting, etc. The solves mass, momentum and energy conservation equations simultaneously in finite different form to evaluate various complex phenomena, such as a laser light-material interaction, liquid metal thermohydraulics in welded pond with a mushy zone, residual stress characteristics in welding processes, etc. The result obtained from the numerical simulation of the laser welding process for different kinds of materials is very encouraging in the sense that the SPLICE code would be used as one of the efficient tools for the evaluation of thermohydrulic phenomena in the welded pond.

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In large-area electron beam (EB) irradiation method, metal surface can be uniformly melted by the large-area EB with the uniform energy density distribution of 60 mm in diameter. Therefore, highly efficient surface finishing of metal can be performed. Furthermore, when the EB is irradiated to the workpiece with convex part, the edge of convex part is rounded since material removal of edge is preferentially performed due to the difficulty of heat diffusion at the edge and the concentration of EB. Thus, it is highly expected that micro filleting at the edge of workpiece can be done by the phenomenon of preferential material removal of the edge of convex part. In this study, the possibility of micro filleting in large-area EB irradiation is experimentally investigated. Experimental results show that the curvature radius of edge increases with acceleration voltage of EB. However, resolidified layer thickness on the upper side surface of workpiece also becomes larger, and uniform resolidified layer cannot be obtained at high acceleration voltage. The micro filleting at the edge with uniform resolidified layer thickness and ideal curvature radius can be achieved by using large-area EB with low energy density and large number of irradiations.

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Ion beam etching is effectively used for the fabrication of high-precision optics. The main application of ion beam etching is to figure large optical surfaces to correct their shape errors remained on polished surfaces. To figure small or medium sized optical surfaces, the generation of ion beam with smaller diameter and higher ion current is required. In this study, we designed a magnetic lens with quadrupole magnets using permanent magnets to obtain ion beam with small diameter. The magnetic lens is installed between the outlet of an ion gun and a chamber, which enables the changing of the trajectory of ion beam in the chamber. Thus, the trajectories of ion beam were simulated when a doublet or a triplet magnetic lens was used. Moreover, ion beam distributions on a workpiece surface were simulated for both magnetic lenses. As a result, the simulations showed that the ion beams can be focused on a workpiece surface when a doublet or a triplet magnet lens is used: the distribution of ion beam on a workpiece surface was simulated to be shrunk from approximately 30 mm to 2.2-5 mm by the triplet magnet lens.

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