It has been reported that shear angle, specific cutting force, and cutting temperature have exponential relationships with cutting speed and uncut chip thickness as experimental equations based on shear plane theory. However, previous reports have mainly studied steel materials, and there have been few reports on nonferrous metals. In this study, we conducted two-dimensional cutting experiments on pure titanium to investigate the relationship between machining conditions. Therefore, this study conducted two-dimensional cutting experiments on pure titanium and investigated its relationship with cutting conditions. The shear angle was derived from the experimental chips, the specific cutting force from the measured principal and back forces, and the temperature from the previously developed constitutive curves. A clear exponential relationship was found between shear angle, cutting speed, cutting thickness, and the product of these parameters (referred to as the parameter "Vh"). On the other hand, specific cutting resistance and cutting temperature were not related to Vh clearly but were related to speed and thickness alone. From these relationships, an experimental equation was developed.

Shear angles must be estimated to obtain cutting temperatures and other data from shear plane models. The shear angle is known to be affected by the cutting speed and hardness of the work material, however there is no equation that takes these factors into account. Therefore, this study describes an experimental equation for shear angle that takes into account cutting conditions and material properties. In the experiment, the experimental equation for shear angle proposed in the past for quasi-orthogonal cutting on a lathe is verified to be valid in actual orthogonal cutting. The coefficients of the experimental equation are expected to depend on the hardness of the material and the cutting conditions. Therefore, the coefficients were calculated by performing orthogonal cutting on S55C whose hardness was changed by heat treatment under several different cutting conditions, such as cutting speed and cutting thickness. As a result, it was found that the relationship between various cutting conditions and shear angle that was established in quasi-orthogonal cutting was also established in actual orthogonal cutting. Experiments also revealed the values of the coefficients of the experimental equation.

Until now, Pb added bronze has been used to improve machinability, but various regulations are in place due to the harmfulness of Pb to the human body and the environment. For this reason, Bi-based Pb-free bronze has been developed, but it has the problem of being inferior in machinability to Pb-containing bronze. In this study, the effect of Bi addition on the machinability of Pb-free bronze was investigated. In the experiment, a two dimensional cutting test apparatus was used to perform cutting experiments on bronze with different concentrations of Bi added, and friction and shear yield forces were investigated. In addition, a SEM was used to observe the cutting chips and the state of the Bi. As a result, it was found that the addition of Bi reduces the friction coefficient between the tool and the chips and the shear yield force of the chips, improving machinability. It was also found that the effect increases when the amount of Bi added is increased up to 1.0%.

This study aims to achieve alcohol lubrication, a novel lubrication technology in the machining of aluminum alloys. Initially, the machinability was evaluated by supplying alcohols with different wettability to the machining area, and the key factors influencing alcohol lubrication were identified. Subsequently, to stabilize alcohol lubrication, textured tools were developed. The results showed that compared to conventional tools, textured tools significantly reduced cutting force in a wide range of cutting conditions.

In the field of machining with special shape tool with curved edges, it is recognized that the posture of the tool effect of the cutting surface properties. However, the specific effects of this posture are not yet fully understood. The tools are known for their high efficiency in machining, but the shape of the cutting edge imposes limitations on the tilt angle. Consequently, our study concentrated on the lead angle, which offers a relatively high degree of freedom. We conducted a series of cutting experiments in which the lead angle was the only variable and developed a cutting model using a 3D CAD system. Observations of the cutting surface and cutting chips revealed that when the lead angle was positive, the cutting process became unstable, and a deterioration in surface properties. The cutting model demonstrated that the crosssectional area at the commencement of the cut is reduced under these conditions. Furthermore, during one complete rotation of the tool, the cutting edges are disengaged from the cut within the range that remains on the cutting surface. Therefore, when the lead angle is positive, the cutting mechanism is more susceptible to unstable cutting and burr formation.

The effects of various machining conditions on cutting force and surface roughness during aluminum alloy cutting using a barrel tool were investigated. Because the shape of the barrel tool is special, it was found that changes in the machining shape due to the contact position of the tool have a large effect. It was confirmed that the machining conditions that set the tool posture unique to 5-axis had the greatest influence on cutting force and surface roughness. I compared the machining time with a ball end mill under the optimized conditions and confirmed that machining can be done 7 times more efficiently.

Recently, hobbing using a multitasking machine has been investigated as a method for machining arbitrary tooth profiles in hobbing. However, the use of cantilevered hobs is expected to reduce machining accuracy due to reduced tool rigidity. To prevent this, it is necessary to create a machining path that takes tool deformation into account or to perform cutting under machining conditions that do not deform the tool. In either case, it is important to know in advance how cutting forces change when machining conditions are changed. There have been several studies in which cutting forces have been predicted by numerical calculations using computers. However, these studies did not consider tool or workpiece deformation, and it is unclear whether the same model can be applied to the use of a cantilevered hobbing tool. Therefore, in this study, we developed a method for predicting cutting forces that takes tool deformation into account. The developed system was verified by machining experiments using multitasking machine and rotary dynamometer. A comparison of the prediction accuracy between the cutting force calculation system that takes tool deformation into account and the cutting force calculation system that does not take tool deformation into account showed that the error was reduced by up to 3% compared to the cutting force calculation system that does not take tool deformation into account. However, the prediction error remained due to the use of a simplified cutting force calculation model.

Various cutting-force estimation methods based on different disturbance observers have been proposed. However, each method has a modeling error, decreasing the estimation accuracy in a certain frequency band. In order to compensate for the modeling error and improve the performance, we have proposed that three different cutting estimation methods are integrated by using a neural network. In this study, the influence of friction compensation and input data on the cutting force estimation is analyzed. The results showed that estimation accuracy remarkably decreased when friction compensation was not implemented, and the accuracy decreased including the experimental conditions of interpolation and extrapolation experiment conditions when directly inputting servo informations to a neural network.

High performance cutting requires the selection of optimal conditions for the appropriate machining process. Identification of the appropriate model parameters in the cutting process is essential in achieving highly accurate cutting simulations, which are effective for the process optimization. During end milling, tool damage deteriorates the geometry of the side cutting edge as well as localized damage on the corner cutting edge as the cutting distance increases. The conventional model does not consider the effect of corner edge damage on the cutting force. When tool wear occurred, the accuracy of the cutting force estimation deteriorates. Therefore, we proposed a model and parameter identification method for the corner edge damage. We used the averaging method and the discrete method for parameter identification. The tool life test verified that the corner edge model improves the accuracy of cutting force estimation significantly. In addition, performances of the parameter identification by the averaging method and discrete method are compared. Analytical investigations clarified the highly accurate identification ability of the discrete method that enables the accurate identification from the reference data measured at only one axial cutting depth condition. The proposed model is expected to attain highly accurate prediction of chatter stability.

This study proposes a method for estimating surface hardness and residual stress in turning of carbon steel. The machined surface properties depend on the strain, strain rate, stress and temperature fields generated during cutting. Therefore, the strain, strain rate, stress and temperature fields are estimated from the cutting force using shear angle theory and a three-dimensional cutting model, and the hardness and residual stress are estimated using a linear regression model. The accuracy of the residual stress and hardness estimation was analyzed through validation experiments. In addition, the effect of modelling errors in the turning process simulation on the accuracy of hardness and residual stress estimation was analyzed. In the verification experiment, the cutting force, flank wear width, chip thickness, hardness and residual stress were measured. The analytical results clarified that the hardness and residual stress could be estimated accurately. The influence of the modelling error in the shear angle prediction is negligible on the estimation accuracy.

Difficult-to-cut materials, which are increasingly used in the aerospace and energy industries, cause significant tool wear and high tool temperatures during machining. Turn-milling is one of the machining methods that are currently attracting attention as a solution to these problems. The main feature of turn-milling is that the milling tool cuts the work material rotating at a low speed, and the intermittent cutting by multiple cutting edges has the advantage that cutting heat can be dispersed to each cutting edge and chips can be broken up reliably. In turn-milling using a 5-axis machine, there are various options for tool posture, which makes it difficult to understand the cutting status. In this study, a point cloud model is used to simulate machining with tool postures such as tilt and lead angles of the tool rotation axis. The surface roughness is to predict the effects of cutting conditions and tool posture parameters in 5-axis turn-milling, focusing on the generated cut trace shape and surface properties.

High-hardness steels, which are often used as materials for machine element parts, are considered to have poor machinability because they are quenched and tempered and have excellent mechanical properties and wear resistance. In this study, we experimentally examined the effect of micron-level depth of cut on the hardness of chrome molybdenum steel using commercially available PVD-coated cemented carbide tools. The results showed that the change in hardness varied greatly depending on whether the tool was quenched or not, and that the hardening was more pronounced in the quenched area.

The occurrence of chatter vibration during machining can cause a reduction in dimensional accuracy and surface quality, which can hinder highly efficient machining. A method to avoid the occurrence of chatter vibration is to derive a stability diagram that clearly shows the relationship between spindle speed and depth of cut in the stable and unstable regions. To derive the diagram, it is necessary to identify the modal parameters of the system. Impulse response testing, a common method of identifying modal parameters, may not be suitable in actual industrial settings due to variations in operator skill and limitations in sensor mounting. In this study, we propose a method to identify the modal parameters by inverse analysis based on the properties of the Lissajous figure, which represents the reaction force and displacement of the system. In addition, through cutting experiments, the applicability of the proposed theory to real cutting environments is investigated and the results are presented.

PI resin is non-thermoplastic. Compared with thermoplastic PEEK resin, it has higher heat resistance, dimensional stability, and wear resistance. Therefore, it is a component material in various aerospace, automotive, and semiconductor industries. However, in the cutting process of PI resin, burrs generated during the machining process cause deterioration in product quality and obstacles in subsequent processes. This study investigated the effect of cutting conditions on burr generation in small-diameter drilling for the machining of PI resin parts. As a result, within the experimental conditions, drilling at a step of 0.05 mm and a feed rate of 100 mm/min and removing chips adhering to the tool by air before the final step were the optimal machining conditions for burr suppression in the drilling of PI resin. This enables high machining accuracy and efficiency of small-diameter holes in PI resin.

Currently, WC-Co sintered carbides are the most common cutting tool material, and they have excellent hardness and wear resistance. However, W and Co are rare metals, and they have disadvantages such as being expensive due to limited resources and being harmful to the human body. So we have been studying TiCN-FeAl tools, which are rare metal-free sintered tools. In a previous study, we reported that the TiCN-FeAl tool was more wear resistant than commercially available tools but was prone to chipping. In this study, cutting tests were conducted on a pure iron alloy with high ductility, and the effects of sintering conditions of cutting tools on tool wear were investigated through wear and edge observations.

Under ideal conditions where no adhesion wear occurs at all, cutting at the cutting speed just lower thermal wear becomes dominant is considered to be the machining condition that achieves both high removal rate and long tool life. This paper proposes a method to search for suitable cutting conditions by measurement of the tool wear at the same cutting distance at three cutting speeds V, V/2 and 2V, and, if necessary, by conducting another cutting experiments at cutting speeds of 4V or V/4 and so on in order to estimate the lowest cutting speed at which thermal wear dominates. The effectiveness of the proposed method was also verified for dry turning of austenitic stainless steel (JIS SUS304) with cemented carbide tools (K, M, P grade CNMG inserts and a M grade newly developed commercial insert). The experiment was conducted at the cutting speeds 40, 80,160, 320m/min. Notch wears on major and minor cutting edges, and wear width of relief face were measured at the cutting length around 500m. Although the method is simple, it provides a guide to search cutting conditions. The newly developed insert had better cutting performance than CNMG insets from the viewpoint of tool wear.

In machining process of rolled aluminum material, residual stress is generated on surface of product during rolling and cutting, resulting in deformation of the product. In this study, deformation due to residual stress was predicted. Specifically, the following methods were used. First, residual stresses on the surface of the material after rolling and machining were measured for the object for which displacement is measured. Furthermore, by referring to the internal residual stress in the material for which displacement is not measured, the residual stress inside the material for which displacement is measured was assumed. Next, the assumed residual stresses were analyzed by converting them to the effect of thermal stress on the geometry after machining. Finally, to account for the anisotropic nature of the residual stress, the analysis was performed for each direction of the residual stress, and the displacements were added together. The results of the analysis were verified by comparing the Z-axis displacements with the analytical values after cutting and deformation measurements were taken. Similar trends to the analytical and measured values were observed in the short material direction, and different trends were observed in the long material direction. As a result, the influence of shape error due to residual stress generated during rolling and cutting was analyzed, and the deformation was partially predicted.

When serrated chips are generated, the average chip thickness becomes thinner, and thus cutting resistance can generally be reduced. The generation of saw-tooth chips can sometimes be accelerated by grooving the surface of the workpiece with a fine pre-cracked groove in front of the cutting point. This saw-tooth chip formation enhancement in ductile materials and in low-speed cutting, which deteriorates machinability, reduces cutting resistance and improves machinability. This paper investigates the optimum pre-cracked groove shape and size conditions through numerical analysis and experiments. Experimental results showed that the best reduction in cutting resistance was achieved when grooves were applied to the workpiece surface with a groove width of about 0.5 to the depth of cut. The maximum reduction in cutting resistance was 70% compared to that without pre-cracked grooves. Numerical analysis was performed to investigate the difference in cutting resistance reduction with groove width, but no difference was observed in the analysis results. It is considered that factors not taken into account in the numerical analysis are actually occurring.

In recent years, gear skiving has gained attention as a highly efficient machining method for internal gears used in reducers. This process involves the synchronized rotation of the workpiece and tool, enabling the continuous machining of multiple teeth and thus achieving high machining efficiency. However, a significant challenge with this method is the reduction of tool life. To address this issue, it is necessary to calculate tool wear conditions and cutting resistance. Previous studies have estimated the cutting thickness of various parts of the cutting edge and predicted cutting resistance during gear skiving through numerical analysis. In these analyses, the intersection of the region where the tool's cutting edge passes once for each groove of the workpiece and the region where the cutting edge passed previously is determined by sequential processing. However, this method imposes a high computational load due to the numerous intersections that need to be derived, resulting in calculation times several times longer than the actual machining time. To overcome this challenge, I developed a method to reduce calculation time by replacing sequential calculations with parallel processing. The developed method utilized a GPU, an ultra-parallel computing device, to achieve high-speed computation. As a result, the execution time of the program was reduced to approximately 50% compared to previous studies, and similar cutting force data was obtained.

In recent years, five-axis machine tools have been widely used for machining complex-shaped parts. However, in simultaneous 5-axis machining, which involves rotational movement, the speed and movement paths of each axis vary depending on the workpiece holding position, even with the same machining method. Additionally, significant acceleration and deceleration in the axis movement can lead to synchronization accuracy issues and consequently poor machining accuracy. In this study, by utilizing the fact that acceleration is controlled by jerk, a program was developed to explore the workpiece holding position where the jerk remains below a certain value. This was achieved by converting the movements of each holding position candidate within the machine tool for the given machining data into coordinates, approximating their trajectories, and differentiating them to derive the jerk values. The results confirmed that it was possible to compare the magnitude of acceleration and deceleration associated with the movement for each holding position by comparing the derived holding position with other holding positions.

Prediction of tool edge wear and loss can be an important technology in ultra-precision machining. Especially in ultrasonic elliptical vibration cutting of steel materials, where diamond tools can be used, the need for this technology is even greater because of the dynamic cutting environment. For this purpose, it is necessary to know the loading state of the tool cutting edge, but it is difficult to measure the stress field directly. However, it is relatively easy to measure the deformation field due to the recent development of image correlation methods. Here, we present the results of a trial measurement of the deformation field near the tool edge during ultrasonic elliptical vibration cutting and discuss the loading state of the tool edge.

This study investigates high-precision micro-machining of difficult-to-cut materials using polycrystalline diamond (PCD) blade tools. Conventional electroplated blades face limitations in achieving fine grooves due to buckling deformation. To address this, the research focuses on using PCD blades, which offer superior strength and hardness. An electrical discharge machining (EDM) devices was designed and tested to further thin the PCD blades. The EDM process was applied to shape and sharpen the PCD blade edges, resulting in visible discharge marks along the blade periphery. Blade thickness was reduced from 21.6 μm to 18.0 μm through EDM on both sides. The modified PCD blade was then used to machine grooves in PMN-PT piezoelectric crystals. While the blade thickness was 18 μm, the resulting groove width was 25 μm, likely due to blade vibration and misalignment issues. The groove bottom surface roughness was measured at Ra 110 nm, with some grinding marks and micro-cracks observed. The study demonstrates the potential of PCD blades combined with EDM for ultra-fine groove machining, while highlighting areas for further improvement in blade stability and alignment to enhance machining precision.

RISA grinding method using cerium oxide slurry has been proposed for grinding optical glass lenses. While the surface quality can be maintained at high feed rate and depth of cut, there is a problem that the profile error increases toward the center of the workpiece. The workpiece is SSG and the grinding wheel is a resin diamond wheel. In this study, the relationship between dwell time and depth of cut is experimentally investigated, and dwell time control method is proposed to achieve a uniform depth of cut. This method changes the rotation speed of workpiece to keep the slurry dwell time constant regardless of the distance from the center of workpiece. The effectiveness of this method was evaluated through orbicular machining tests. With conventional RISA grinding, the grinding trace becomes deeper as it gets closer to the center of the workpiece. By using dwell time control, the depth of the grinding trace is almost the same regardless of the distance from the center.

The relative motion between the tool and the workpiece is transferred in machining, making the precise identification of their relative positions essential for achieving high-precision machining in addition to ensuring the motion accuracy of the machine tools. This identification process, typically conducted before machining, is crucial for setup. Although several on-machine identification methods for tool-workpiece relative positions have been suggested, they are often either indirect or costly. Consequently, none combine high precision, high efficiency, and automation capabilities. In this study, a method for detecting contact between the tool and the workpiece surface during the milling process is developed, allowing direct identification of the relative positions between the tool and the workpiece used for actual machining. A conduction circuit is installed between the tool and the workpiece, and regression analyses of the conduction signal are performed to identify precise contact positions using a duty-ratio-based model and an integral-value-based model. The effectiveness of the proposed method is evaluated through experiments, demonstrating that the proposed method successfully identifies the relative position between the tool and workpiece with high accuracy, achieving less than 1 μm precision.

Thermal errors account for 70% of machine tool errors. Most of the studies for estimating thermal errors are based on a single point where thermal displacement is measured. In this study, the thermal expansion of a ball screw shaft was determined from nut and bearing temperatures for a 3-axis machining center, and the effect of the ball screw was considered in a finite element analysis based on multi-point temperature mapping of the structure. The spatial error was calculated using two methods: a finite element analysis and a simultaneous transformation matrix created using the calculated thermal expansion of the ball screw. This resulted in a spatial error map for the machine tool.

Chatter is a type of vibration that occurs during machining on a machine tool. Active vibration control has attracted attention as a method for suppressing chatter vibration. In the active vibration control based on vibration measurement, a controlled excitation force is input via an actuator in response to the measurement signal. Actuators such as electromagnetic type and inertial type have been used for vibration control.[2] However, these actuators are not responsive enough to control the high-frequency vibration that occurs in machine tools. In addition, to increase the output, the actuators have to be larger in size and installed farther from the tool tip. In this study, an active vibration control with multiple piezoelectric actuators was verified by numerical simulation to suppress chattering vibration. Piezo actuators are highly responsive, small, and capable of large outputs. As a result, 94% vibration suppression was numerically achieved with four piezo actuators. This result suggests that vibration control by multiple piezo actuators is effective in suppressing chattering vibration of machine tools.

In cutting process, chatter vibration is a problem that deteriorates machining accuracy. Self-excited vibration is one of the most common types of chatter vibration, and it must be suppressed because it can suddenly become large vibrations. In a previous study, a method was proposed that changing the rigidity of the machine tools for suppressing chatter vibration without changing the machining conditions. However, the method for changing machine tool stiffness was by manual setting. In this study, the stiffness changes of a brace bar attached to a desktop machine tool is performed automatically by using a servo motor. We developed a new device to change the stiffness controls and attached to the machine tool. The effectiveness of the automatic stiffness control is evaluated through hammering and machining tests.

In recent years, production has shifted from low-mix high-volume production to high-mix low-volume production and variable-mix variable-volume production. In order to realize variable-mix, variable-volume production, it is necessary to actively promote process integration using multitasking machines and automation using robots. However, there are still issues in the automation of setting optimal cutting conditions and tool life management in response to changes in workpiece types. In a previous study, we developed a system that enables measurement of the minor flank wear width using image processing by photographing the minor flank face a camera mounted on a lathe, and found that the system is effective in measuring different coated tools under dry environments. In this study, the availability of this system for different cutting environments was examined. As a result, it was found that the measurement of the minor flank wear width by image processing was sufficient even in a wet environment.

In micro-welding of glass by using a laser, tightly focusing of high intensity ultra-short pulsed laser causes a nonlinear light absorption phenomenon inside the glass in the vicinity of focal point, and the micro-welding of glass is possible by locally internal melting. However, a large stress generates by the sudden change in the temperature during melting according to the concentration of laser energy in the vicinity of the focal point, and cracks formed inside the glass would deteriorate the bonding quality. In order to avoid the occurrence of cracks, it is important to control the energy distribution of laser beam. Thus, in the micro-welding of borosilicate glass using a picosecond pulsed laser, the energy distribution was controlled using a spatial light modulator (SLM). The separated laser beams by SLM were focused inside the glass at the multiple-point to control the energy distribution, and the shape of molten area and the welding characteristics were investigated. The separated laser beams at the multiple-point could form a rounded molten area, and the dispersion of laser energy from one beam to multiple beams enables the relaxation of energy concentration, which would contribute to suppress the occurrence of cracks during the welding process even by using a large energy condition. In addition, the arrangement of separated laser beams in the scanning direction has a possibility of functions as pre- and post-heating, which can reduce the generation of large stress by avoiding the sudden temperature change.

Lead zirconate titanate (PZT) is a piezoelectric ceramic material widely used for sensors and actuator components in the industry. There is an increasing demand for fabricating high aspect ratio microgrooves in PZT. However, conventional grooving methods make it difficult to fabricate such grooves due to the formation of wall tapers, which leads to functional defects in devices. In this study, we proposed a method to fabricate high aspect ratio microgrooves by femtosecond pulsed laser irradiation, which produces low thermal effects and generates high-quality grooves with a minimized taper angle. The fundamental processing characteristics were investigated by changing the laser fluence, the number of scans of the laser, and the laser scan pattern. It was found that the taper angle converged to a specific value by increasing the number of scans, and that the aspect ratio increased and the taper angle decreased when using a rectangle scan pattern. Based on these results, high aspect ratio grooves with an aspect ratio of 3.25, a taper angle of 1.8°, and a surface roughness of Ra 0.5 μm were successfully processed by using favorable processing conditions. The result of this study shows the potential of processing high-precision high aspect ratio grooves and slits with steep or perpendicular walls on PZT and other ceramic materials.

The microchannels have many advantages, such as reagent saving, energy saving and improved reaction efficiency due to shorter reaction time. For example, the microreactors with the microchannels can generate mixed reactants in a short time. In this study, the microchannels were formed by scanning the CO₂ laser beams on the fused glass substrates. Then, it was considered to generate the turbulence flows in the microchannels, since the fine continuous dimples on the bottom surfaces of the microchannels are generated by varying the overlap rate of the pulsed laser. As a result, it was found that the turbulence flows tended to occur, since the bigger dimples were formed due to the longer pulse width with the lower overlap rate. On the other hand, the turbulence flows were unlikely to occur, since the smaller dimples were formed due to the shorter pulse width with the higher overlap rate. Therefore, the mixing effect and the reaction efficiency of the microreactors would be improved by forming the larger continuous fine dimples on the bottom surface of the microchannels with the lower overlap rate, since there is a relationship between the size of the dimples and the turbulence flows in the microchannels.

The flow and solidification processes of molten metals occur in many processes, such as casting and welding, and understanding the quenching and solidification process is important. However, it is difficult to observe these processes under high magnification in close proximity because of their high temperature. In this study, glass was used as a mold to fabricate microchannels inside. The molten metal was filled into the channels and observed with a high-speed camera with high temporal and spatial resolution. Flow behavior was classified with single step flow (SSF) and double step flow (DSF); DSF was obtained up to the end of the channel, which was about 1000 μm long, and was fast due to it flowed away from the wall surface. In addition, cross sectional observation of the metal after filling revealed multiple internal voids. It is thought that solidification of the root stops the supply and rapid cooling at the wall surface stops the flow.

In recent years, there has been increasing interest in Additive manufacturing (AM) as a processing method that consumes less material compared to machining. Among AM techniques, Directed energy deposition (DED), which locally melts and solidifies material to continuously stack beads and create three-dimensional structure, has been gaining attention. This method is characterized by low equipment and material costs, and high construction efficiency.

However, one issue with DED is the low shape accuracy of solid structures. Therefore, this study aims to tackle the correction of the shape of build structure by devising a torch feed rate plan, with the goal of smoothing the top surface of the construction. In this research,wire-arc directed energy deposition (DED-arc), a type of DED, was employed. Experiments were conducted to investigate the trends in layer height based on XY positioning, dual-bead on-plate experiments, exploration of suitable feed rate conditions, and evaluation of shape accuracy. In this experiment, there was no improvement in flatness with the proposed feed rate planning method. Parameters such as layer height and width of adjacent beads are crucial for controlling the layer height in solid shapes.

Particle method, which represents fluid as groups of particles, is one of the fluid simulations. In this study, the process of additive manufacturing (AM) using gas metal arc welding was modeled by particle method in which Marangoni effect, the heat input and pressure of the arc are taken into consideration. Vertical wall building was analyzed to investigate the difference in the built shape because of cooling between passes. As a result, the vertical wall with cooling became taller and narrower and its width remained constant even after repeated building. This trend was also observed in the actual building results.

L-PBF (Laser-Powder Bed Fusion) is a kind of AM (Additive Manufacturing) process in which a part is bult in a layer-on-layer manner. In this study, the mechanical properties of maraging steel (Fe-18Ni-9Co-4.8Mo-Ti-Al) manufactured by L-PBF (Laser-Powder Bed Fusion) using powders with different oxygen content were investigated. As a result, nitrogen content of specimen manufactured remained unchanged compared with that of powder, while oxygen content of specimen increased compared with that of powder. In the tensile test and Charpy impact test,ultimate tensile strength and 0.2% proof stress of specimens were equivalent with regardless different oxygen content . However, the ductility and impact toughness of the specimen were significantly decreased with increasing oxygen content. In addition, fractured surface of caused by oxide inclusion was sometimes confirmed in specimen with high oxygen content. Thus, it is suggested that ductility and impact toughness of the specimen manufactured depend strongly on the increase oxygen content.

Friction surfacing based on solid phase welding requires finishing process owing to the relatively low dimensional accuracy of the deposited layer. The friction welding machine with numerically controlled pressure are commonly used in friction surfacing, indicating that deposition and finishing processes are not integrated. Therefore, this study conducted friction surfacing by a vertical machining center and investigates the effects of machining conditions feed distance along forward (X) and axial force (Z) directions, and spindle travel speed on the controllability of friction load (along Z-axis) and material efficiency. Friction load increased with an increase in spindle travel speed even when Z/X (the ratio of Z-axis feed amount to X-axis feed amount) was decreased, and the best load stability was obtained when Z/X = 0.4. Friction loads were unstable at Z/X = 0.2, 0.8. When the spindle travel speed was increased, material efficiency evaluated from mass of depositions decreased, and material efficiency evaluated from the cross-sectional area of depositions increased. Total material efficiency was not affected by spindle travel speed.

Wire and Arc Additive Manufacturing (WAAM) uses active cooling methods such as water cooling to prevent crystal grain enlargement due to high heat input. However, water cooling of magnesium (Mg) alloys in a high-temperature state is not suitable because of the risk of combustion and explosion. In this study, we propose an active cooling method in which two copper blocks with internally circulating cooling water is brought into direct contact with the fabricated wall component. The effect of active cooling on the temperature and strength anisotropy of the Mg fabricated wall components was investigated. As a result, the temperature during fabrication was lowered by active cooling. The crystals became smaller and grew into equiaxed grains because of the reduction in temperature. The mechanical properties in the build-up direction were improved due to grain size reduction. The strength in the torch feed direction was higher than in the build-up direction. Active cooling reduced strength anisotropy.

Wire Arc Additive Manufacturing (WAAM) offers significant advantages such as low cost and high build speed among additive manufacturing techniques. However, it suffers from cumulative height errors leading to poor shape accuracy and slag formation from deoxidizers causing arc ignition failures. To address these issues, this study explores a hybrid process combining WAAM and machining, specifically proposing interlayer cutting. Using a 5-axis machining center equipped with a welding torch, we employed mild steel wire on SS400 base plates. Comparative evaluations reveal that interlayer cutting effectively reduces arc ignition failures and improves shaping accuracy. Tensile tests confirm that interlayer cutting contributes to enhanced mechanical properties, with increased frequency of interlayer cutting further amplifying these improvements. This research demonstrates that integrating WAAM and machining offers a viable solution for achieving high-precision and high-quality manufacturing, addressing both the shape accuracy and mechanical property challenges inherent in WAAM.

The metallurgical structure of martensitic stainless steels changes with temperature transition. It is difficult to get the desired hard structure with fabricating by using conventional manufacturing way in Wire and arc-based additive manufacturing (WAAM). The reason is that WAAM repeats heating and cooling. In this study, We propose a new manufacturing method: thin layers are continuous manufactured at high speed without stopping between passes. Objects were made hotter and had simple temperature history. In addition, we used two different water cooling processes for the new method. As a result, the objects manufactured by conventional methods not only had uneven hardness as in other studies, but also had bad corrosion. In contrast, the objects manufactured by proposed method had uniform hardening and good corrosion resistance comparable to rolled steels. In particular, the hardness of objects cooled by simultaneous water cooling during manufacturing was close to expected max. hardness. However, when water cooling was applied to the proposed method, the tensile strength was low and varied. This is thought that be influenced by hydrogen. SUS420j2 is known as a material that is easily embrittled by hydrogen. It is necessary to pay attention to delayed cracking and to perform low-temperature tempering treatment.

Wire and arc based additive manufacturing (WAAM) has the advantage of fabricating with multiple types of materials, and localized material changes. Therefore, it is expected to be a means to realize multi-material fabrication. The objective of this study is to fabricate stainless steel and copper alloys as dissimilar metals and to impart arbitrary thermal anisotropy to the fabricated structures. In this experiment, a composite structure containing air layers was devised and fabricated using WAAM. The fabricated composite structure was heated using a rubber heater, and the temperature changes of a measurement surface was photographed with a thermography camera. In the 100-120 °C range, the composite structure transferred more heat in the vertical direction (A), but less heat in the horizontal direction (B). Specifically, the heat transfer was 2.23 times greater in the vertical direction (A) than in the horizontal direction (B) through air layers. It was clarified that the composite structure has thermal anisotropy.

Wire and arc additive manufacturing (WAAM) is one of the metal additive manufacturing methods. It can be used to deposit dissimilar metals. However, it is sometimes difficult to deposit dissimilar metals because their physical properties are different. So, we observed molten pool by using high-speed camera and measured the temperature field of molten pool with two-color thermography to investigate the effect of physical properties of each material on the temperature and size of molten pool.

This study investigates deposition of different aluminum alloys and the influence of added elements on their mechanical properties. Focusing on wire and arc additive manufacturing (WAAM), this study aimed to address the constraints of conventional fabrication, particularly in the context of multi-material applications. WAAM was utilized for the precise deposition of 5000 series aluminum alloys onto robust 7000 series counterparts, and the results were analyzed to characterize dissimilar aluminum alloy interactions. The deposition process employed an advanced WAAM system equipped with an industrial robot, dual-axis positioner, and cold metal transfer welder, coupled with A5356 wires and A5052/A7075 plates as materials. Elemental analyses, hardness tests, tensile testing and Corrosion Testing were performed, revealing a distinct transition layer, which indicates an interplay between dissimilar alloys during deposition. Heat treatment not only restored the hardness of the 7000 series alloy, but also increased its corrosion resistance. The resulting tensile strength surpasses common 5000 series aluminum alloy benchmarks. The study evaluates interfaces under accuracy considerations, highlighting the practical applications of dissimilar aluminum alloy additive manufacturing.

In recent years, the need to reduce CO2 emissions from transportation equipment in response to stricter global warming gas emission regulations has attracted attention to the use of dissimilar metal deposition of steel, the main structural material of automobiles, and Al alloys, which are widely used as lightweight metals. However, dissimilar metal deposition of steel and Al alloys have a problem that a brittle intermetallic compound layer (IMC) is formed at the interface, resulting in a decrease in bonding strength. In this study, we investigated the feasibility of improving the bonding strength between mild steel and Al alloys by using a mechanical interlock structure. Tensile test piece ruptured at values between 30 and 60 MPa. In the 10- and 20-layer cases, the mechanical interlock structure exceeded the tensile strength of the Al alloy. In the case of the 15-layer specimen, the mechanical interlock structure worked for about 25 mm, and the strength was 0.78 kN/mm.

Fused Filament Fabrication (FFF) in the Additive Manufacturing (AM) is a widely popular method in which thermoplastic resin is melted and extruded through a nozzle. However, it has issues such as anisotropy and the inability to produce smooth curved surfaces. Robotic AM, which uses a vertically articulated robot with more redundant degrees of freedom than conventional AM systems, has been investigated to fabricate curved surfaces while changing the orientation of the layers. One of the effective uses is conformal AM, in which curved layers are arranged along the original geometry. In addition, a method using two vertically articulated robots has been proposed for Robotic AM to avoid singularities. In this study, we propose FFF method for arbitrarily shaped curved surface deposition with avoiding singularities by simultaneously controlling the nozzle-side arm and bed-side arm of a dual arm robot. A system with redundant degrees of freedom was developed using ROS2, and the effectiveness of the method for winding continuous fibers without cutting them was confirmed.

Silver was doped by the solid-state ion-exchange method to glass surface that previously doped with potassium by salt bath method. The results of cross-sectional elemental analysis show that silver-doped depth after potassium doping was smaller compared to that without potassium doping. In contrast, the silver-doped area was much larger than that of silver foil used for the doping, indicating that the silver ions diffused rapidly in the direction perpendicular to the applied electric field, i.e., parallel to tha glass surface. Thus, the effect of silver doping duration on ionic distribution of potassium, sodium and silver in the area outside the silver foil was examined. As a result, it was found that potassium and sodium moved in the depth direction, while silver moved to horizontal direction. Furthermore, silver migrated not only in the horizontal direction but also in the depth direction, albeit over short distances. And as the doping time increased and silver caught up with the doping depth of potassium, the doping rate of silver in the depth direction increased. These result suggests that potassium acts as a barrier against silver migration.ion.

In recent years, the number of patients with osteoarthritis of the knee has been increasing with the aging of the population, and knee joint replacement surgery is a treatment for this disease. A high carbon content Co-Cr-Mo alloy (HC-CCM alloy) with excellent wear resistance has been developed as a material used for this treatment. However, there have been no reports on the cutting characteristics of HC-CCM alloys by milling. In this study, the cutting performance of binderless cBN tools in the high-speed cutting region at cutting speeds of 5.0 m/s or higher. As a result, a surface roughness of 0.6μmRz was obtained even under high-speed cutting conditions, but tool damage on the side cutting edge was significant at a cutting speed of 20 m/s. Therefore, a cutting speed of 10 m/s was the most suitable condition for machining HC-CCM alloys.

Meticulous manipulation is required for bone resection performed in the vicinity of critical organs, such as in spinal surgery. On the other hand, it is also important to perform bone resection in a shorter amount of time, as the longer the procedure, the greater the burden on both the patient and the physician. Until now, two types of tools have been used in bone resection depending on their purpose. One is a cutting tool with high removal efficiency but poor operability. The other is a grinding tool with excellent operability but low removal efficiency. However, it is undesirable to extend the procedure time to switch tools during surgery. Therefore, a tool combining both cutting and grinding mechanisms was used for orthogonal cutting experiments to investigate whether this tool could achieve both high operability and removal efficiency. In the experiment, porcine cortical bone was cut using an SUS440C tool with a diamond grinding wheel electroplated on the tip. The workpiece was tilted and fixed on a table driven by a linear motor so that the cutting depth would increase monotonically. By examining the state of the chips and the cutting force, we found that transitioning from grinding to cutting is possible by increasing the cutting depth. However, a cutting depth of 60 µm required for transitioning to cutting is quite large, and considering the conditions of the rotating tool, the operator would have to handle the tool at speeds several times faster than conventional methods. Therefore, it was found that for adaptation to endoscopic surgical tools, a mechanism that allows the transition from grinding to cutting under more practical conditions is necessary.

Demands of micro catheter parts made of titanium (Ti) are increasing in medical devices, because Ti is light, tough, and has low aggression. However, melting point of titanium is high and it is easy to adhere to the cutting tool, and then the tool life is short. In this study, the ultrasonic vibration assisted coolant was applied to cutting in order to reduce the cutting force, to increase preciseness, and to increase the tool life. In the experiments, a microtool made of cBN of Φ 0.3 mm diameter was produced in trial and Ti plate was drilled using the ultrasonic vibration assisted coolant system and the effects of kinematic viscosity coefficient of the coolant on the vibration performance and tool life.