Cutting force in drilling of Ti-6Al-4V is studied with simulation based on a predictive model. In the force model, three-dimensional chip flow is made by piling up the orthogonal cuttings in the planes containing the cutting velocities and the chip flow velocities, where the cutting model in each plane is made using the orthogonal cutting data. The chip flow direction is determined to minimize the cutting energy. The cutting force is predicted in the determined chip flow model. The force model is verified in comparison between the predicted and the measured cutting forces. In the rolled titanium alloy, anisotropy is observed in the cutting force. Because the cutting edges rotate in drilling, the cutting force changes periodically with the cutting direction with respect to the rolling direction. Hardness change in subsurface is also measured with a nano indenter. The hardness of the titanium alloy increases around 10 µm underneath the machined surface. Meanwhile, hardness of 0.50% carbon steel does not change. The strain hardening effect is considered by the shear stress on the shear plane in the orthogonal cutting data in the force model.

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A micro-probe based on laser trapping has been proposed for the probe system of a nano-coordinate measuring machine. This study focused on the “shadow effect,” which is the case wherein a partial beam for laser trapping is shaded by the specimen. A radially polarized beam was introduced to improve the shadow effect. As the result of increasing the trapping efficiency by 3.2 times, this high-efficient laser trapping made it possible to extend the measurable range of the vertical surface under the shadow effect.

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The ultrasonically assisted machining is suitable to achieve sub-millimeter drilling on difficult-to-cut materials such as ceramics, hardened steel, glass and heat-resistant steel. However, it is difficult to observe the high-frequency and micron-scale phenomenon of ultrasonic cutting. In this report, high speed camera based on photoelastic analysis realized the visualization of stress distribution on drilling process. For the conventional drilling, the stress distribution diagram showed the intensive stress occurred under the chisel because the chisel edge of drill produces large plastic deformation. On the other hand, the ultrasonic drilling produced spread stress distribution and stress boundary far away from the chisel. Furthermore, chipping or cracking of inner wall of silica glass was influenced considerably by cutting fluid.

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The purpose of this study is to clarify the relationship between the dynamic motion errors of feed drive systems and the machined surfaces. To achieve this purpose, a simulation method for a machined surface by peripheral milling is proposed. In the proposed method, the motion errors of a feed drive system and the machined surface are simulated based on tool diameter, number of flutes, spindle speed, and feed speed. In addition, to clarify the correctness of the proposed method, actual cutting tests are carried out. In the cutting tests, the control parameters of the machine tool are intentionally changed to obtain the motion errors. As the results of the cutting tests, it is confirmed that the influence of the motion errors of feed drive systems on machined surface can be predicted by the proposed simulation method. The relationship between the motion errors and machined surfaces is also examined based on the simulations.

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This study aims to discuss an application of self-assembled particles to a polishing tool. Self-assembly of fine particles is obtained by drying colloidal suspension on a substrate. Using a dispenser and a motored stage, an assembly can be obtained along specific profile like spiral. The assemblies are transferred to another substrate on which ultraviolet curing resin is spin-coated and cured while pressing the substrate each other. Silica particles of 1 µm diameter were assembled over 10mm square and applied to polishing to evaluate the performance. It was found that the glass plate was polished with smooth finish. However, the particles dropped off under severe conditions.

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This paper describes the machining characteristics of electrolysis-free micro EDM in water using the electrostatic induction feeding method. With the electrostatic induction feeding method, if deionized water is used for the working liquid, electrolysis can be prevented because bipolar voltage is applied to the working gap. Results of micro-holes drilling showed that the material removal rate with deionized water is higher than that with oil, and the oversize of holes machined in deionized water is smaller. Moreover, micro-holes could be drilled successfully even in a tap water with the oversize of several micrometers using this method.

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In this paper, we investigate the effects of short-circuiting on machining in order to discuss material removal in EDM of CFRP. Sinking EDM of CFRP using deionized water was carried out, and waveforms of gap voltage and current, pulse frequency and servo feed fluctuation, were measured for classifying machining situations, electrical discharge and short-circuiting. The cause of short-circuiting and the relationship between the short-circuiting ratio and material removal rate were investigated. In addition, the potential drop and temperature of short-circuiting carbon fibers were estimated with a simple model. Experimental results show that short-circuiting due to frayed carbon fibers frequently occurs in sinking EDM of CFRP. It is found that the short-circuiting contributes to the material removal in EDM of CFRP.

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This paper proposed a high speed and a high accuracy measurement method for the cutting edge height of a rotary cutting tool with respect to the reference surface on the tool by using a laser triangulation displacement sensor. In the measurement, not only the displacement output but also the light intensity output of the laser displacement sensor, which corresponds to the intensities of the laser beam reflected from the cutting tool surface, are acquired when the laser displacement sensor scans across the cutting edge. To remove the influence of the width of the cutting edge, the cutting edge height is determined from the sensor displacement output when the sensor light intensity output reaches to the maximum. It has been confirmed by theoretical analysis, computer simulation and experiment that the proposed method is effective even when the width of the cutting edge is smaller than the diameter of the laser spot of the sensor.

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In this study, a TiN/HfN-coated tool (THN-HF(L)) was developed to improve the processing efficiency of machining austenitic stainless steel. Using scratch tests, this tool was compared with other film-coated tools, and its critical load showed the highest value. The THN-HF(L) tool, whose film was formed in the low bias voltage condition, has a longer tool life than conventional tools. In high-speed cutting (4 or 5 m/s), its tool life is over 20 km. Even though the THN-HF(L) tool's cutting distance surpasses that of conventional tools, adhesion is controlled, and flaking of the film coating on the cutting edge is not observed.

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Thermal stress cleaving is a prospective technique for separating thin plates of brittle materials such as silicon, ceramic and glass. This study, deals with a new method which provide the initial fracture on the edge of workpiece. The initial fracture such as crack, scratch and groove is the starting point of crack propagation in laser cleaving and the crack propagates along laser scanning path from the initial fracture. In previous study, the initial fracture is created by Vickers indenter. Since shape of Vickers indenter is pyramid, the unnecessary cracks propagate. In addition, lateral cracks are created at the surface. Because of cracks, the quality of thermal stress cleaving is poor. In this study, a pre-groove is used as the initial fracture. The pre-groove is formed on the workpiece surface by pulsed Nd:YAG laser irradiation through a cylindrical micro-lens. The cylindrical micro-lens is made by the irradiation of Er:YAG laser to the surface of acrylic board. Silicon wafer is used as a workpiece. Continuous Nd:YAG laser is used for laser cleaving. By using this method, there is no unnecessary cracks happen, and subsequently improve the quality of thermal stress cleaving.

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The purpose of this research is to produce micro parts reinforced by unidirectional short fibers using laser stereolithography. Ferromagnetic short fibers are added to a liquid photopolymer and a magnetic field is then applied to the liquid photopolymer, aligning the axes of the short fibers along the magnetic field direction. Then, the photopolymer is solidified by UV laser irradiation in a desired shape. Solidified photopolymers containing the unidirectional short fibers are layered until the desired height is obtained. The surfaces of the solidified layers are observed and the possibility of a reinforcing effect between the layers is examined.

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This paper discusses the influence of heat treatment condition of aluminum alloy upon cutting mechanism. The orthogonal cutting experiments of A2017-T3 and A2017-O with a cutting speed of from 0.5 m/s to 160 m/s are conducted. The experiments obtain the following results: A2017-T3 forms discontinuous and serrated chip, while A2017-O forms continuous flow-type chip, regardless of cutting speed. The tendencies of the changes in shear angle, cutting forces, friction angle and the shear stress on the shear plane with the cutting speed are the same between A2017-T3 and A2017-O, when the cutting speed is less than 80 m/s. The significant dissimilarities in the cutting mechanism, however, between A2017-T3 and A2017-O come to appear gradually, when the cutting speed exceeds 80 m/s. For A2017-T3, the shear stress on the shear plane is steady, and the friction angle at the tool-chip interface increases slightly in such a high-speed cutting condition. In contrast, for A2017-O, the shear stress on the shear plane rises gradually, while the friction angle keeps decreasing with the cutting speed. An analysis based on the simple shear model shows that the shear strain rate at the shear zone reaches up to 10⁷ 1/s when the cutting speed is beyond 80 m/s. The appearance of these dissimilarities in the cutting mechanism due to the difference in the heat treatment conditions will depend on the characteristics of dynamic plastic behavior and dynamic friction property of aluminum alloy appearing at high-strain-rate fields.

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This paper describes a two-degree-of-freedom (two-DOF) controlled electromagnetic actuator guided by an elastic hinge mechanism to realize off-axis laser beam cutting. In the laser beam cutting process, a focused laser beam melts and vaporizes part of the workpiece, and the molten material is blown away by an assist gas jet. The cutting speed and quality are related to the flow of the assist gas jet. In order to improve the removal capability of the molten material and to reduce gas consumption in off-axis laser beam cutting, the lens is driven radially by the proposed two-DOF actuator to generate relative motion between the assist gas nozzle and the laser. Experimental results show the prototype actuator possesses a positioning stroke of ±500µm within 3µm of tracking error and bandwidths more than 150Hz in the two-DOF directions. In the acceleration test supposed at a maximum acceleration of 2G, the prototype actuator maintains the relative displacement between the lens holder and the laser head within 10µm. Off-axis laser beam cutting by using the prototype actuator achieves high speed and less dross processing.

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The purpose of this study is to investigate the effectiveness of thrust force signals for estimation of the burr occurring at the outlet of a drilled hole and the prefailure phase caused by tool wear in drilling holes through thin stainless steel plate (JIS SUS304). Micro-drilling tests, using feed rate, step feed length, and the micro-drill diameter as experimental parameters, were carried out to measure the thrust force during peck drilling operations. Tool wear of the cutting edge and burr occurring at the outlet of drilled holes were measured at intervals of a constant number of drilled holes to consider their relationships to thrust force. As a result, the thrust force caused by tool wear during peck micro-drilling is related to the height of the burr occurring at the outlet of the drilled hole and the prefailure phase of micro-drills.

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Micro-grinding is one of the methods to create submillimeter-structures, and it has been applied to many processes such as finishing of internal surface of fuel injector valves and dental technique. Micro-grinding has recently been required to improve ground surface roughness. Slant feed grinding is a machining method to improve finished surfaces, but the mechanism of improving ground surface roughness of slant feed grinding has not been completely clarified yet. This paper proposed a theoretical method for calculating ground surface roughness of slant feed grinding by using a statistical approach. This method can clarify the mechanism, and it can also optimize conditions of slant feed grinding. A self-developed micro-grinding device was then employed to confirm the calculation method experimentally, and the experimental results agreed with the theoretical calculation.

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In electrical discharge machining (EDM), workpiece is machined using heat of the arc-plasma generated in the discharge gap after dielectric breakdown. The characteristics and behavior of the arc-plasma during a single discharge have a great influence on the formation of the discharge crater. In order to improve the machining accuracy and surface roughness of the workpiece, it is quite necessary to research on plasma behavior and its characteristics. In this study, light intensities radiated from the plasma which are considered to reflect the material removal behavior were measured using a spectrometer under different machining conditions. It was found that the starting moment when light intensity was detected had a time delay after the dielectric breakdown. It is because of the time needed for the material to be evaporated before its temperature reaches the boiling point. Besides, the time delay increases accordingly by slowing down the rise speed of the discharge current because of lower heat flux flowing into the surface of the workpiece. In addition, heat conduction analysis was conducted to compare the time delay calculated with the experimental ones. It was found that plasma expanded in a rapid speed within about 180ns right after dielectric breakdown and remained constant with the diameter of about 20µm after that under a roughing condition of micro EDM.

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In this paper, the measurement method of tool edge temperature using a two-color pyrometer with an optical fiber in wet cutting is proposed. Using the proposed method, the high pressure air supplied from the small hole where an optical fiber is inserted prevents coolant from adhering to the optical fiber edge and makes temperature measuring possible. The influence of this supplied air pressure on the tool edge temperature is negligible in the 0.05Mpa to 0.6MPa range. In this way, the temperature of CBN and PCD tool edge is measured in wet cutting of Ti-6Al-4V. As a result, the tool edge temperature increases rapidly with the increase of cutting speed. In dry cutting, PCD tool edge temperature is almost 100 °C lower compared with CBN tool edge temperature. By coolant supply, PCD tool edge temperature decreases greatly. For example, when cutting speed is set at 300m/min, PCD tool edge temperature decreases by 350°C, while CBN tool edge temperature decreases by only 70°C.

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A new method was proposed for replicating snow crystals that uses light-curing resin containing no harmful substances, as the replicating material, and the 3D reproduction of a snow crystal by stereolithography was conducted. It was found that a UV light irradiation density of at least 0.6 mW/cm² was required to complete the light-hardening reaction within 15 min when polyene/polythiol resin (NOA81) was used as the light-curing resin. When the atmospheric temperature was 0 °C, the maximum temperature rise due to the light-hardening reaction was 4.2 °C at an irradiation density of 1.0 mW/cm². This suggests that the initial temperature of the light-curing resin must be approximately -5 °C to prevent the snow crystal from melting when an irradiation density of 1.0 mW/cm² is applied at an atmospheric temperature of below 0 °C. This replication method has sufficient accuracy to reconstruct the 3D shape of a snow crystal. The 3D reproduction of a snow crystal by stereolithography was conducted by transforming the CSV-formatted 3D profile height data to STL-formatted CAD data.

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A measurement system is presented for the surface form measurement of a cylindrical workpiece with periodic microstructures generated on the outer surface of the workpiece. The main components of the measurement system are a spindle to rotate the workpiece, and an air-bearing displacement sensor with a diamond micro stylus to detect the surface form of the workpiece. The surface form of the micro-structured workpiece was measured in different rotation speeds and the relationship between the measurement repeatability and the rotation speed was investigated. The Fourier transform analysis and the wavelet transform analysis were employed to analyze the measurement results in the time-frequency domain for the identification of the error sources with specific frequency characteristics.

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Recently, micro holes processing on glass were focused on chemical and biological filed. Authors focused on Electro-Chemical Discharge Machining (ECDM) to machine micro holes on glass, and developed the ECDM device. This paper reports about feedback circuit for machining-stop system and two-step machining which were developed to reduce the smallest diameter of micro hole. Additionally, the tool electrode of which diameter was 20 µm was produced using Electro-Chemical Machining (ECM). As a result, the diameter of micro hole was reached to 12 µm.

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This paper reports in-process detection of tool wear by using tool-work thermo-electromotive force (E.M.F.) as a sensor signal in face milling. In the case of using a single cutting edge, E.M.F. at the beginning of cut increased slowly corresponding to the width of tool flank wear. We assume this phenomenon is due to variations in electric resistance by increase of the contact area between the workpiece and the tool, so electric current between tool and workpiece was also detected. The variations of contact electric resistance calculated from both the E.M.F. and the electric current reveal that the electric resistance decreases as the tool flank wear progresses because contact areas between tool and workpiece increase. We developed a measurement system of variations of the contact resistance during face milling process. By monitoring the contact resistance using this system, the real-time detection of the width of tool flank wear can be achieved stably during intermittent cutting operations.

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We propose a flexible circular saw for high-speed cutting of curved lines in carbon fiber-reinforced plastic (CFRP). A conventional circular saw is appropriate for straight line cutting, but it cannot be applied to curved line cutting because of the interference between the saw body and the machined surface. To eliminate this problem, the flexible circular saw is deflected into a bowl shape by circular forced displacement, and the cross-section of the saw becomes a circular arc. A curved line can be cut by the bowl-like-deflection. The deflection shape is very important to realize the curved-line cutting without interference. We investigated the deflection of the flexible circular saw by a finite element method (FEM) analysis. Suitable slit shapes for the saw body are also proposed, based on the FEM results regarding stress in the saw body, the minimum radius of curvature, and the effects of cutting force and centrifugal force and eigenvalue. We also conducted a curved-line cutting test on a CFRP plate, and we found that the flexible circular saw can cut curved lines with high accuracy and high speed without interference between the saw body and the machined surface.

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Recently, high-speed micro-milling has attracted considerable attention for effectively manufacturing fine and precise machine components with lower cutting resistance. However, as the tool diameter is reduced, higher rotational speeds of the spindle become necessary for machining components at the optimal cutting speed. We propose a new machining method in which an end mill cutter is directly supported by aerostatic journal and thrust bearings, and driven by air turbines to achieve high rotational speeds. We found that the proposed micro end mill spindle with a 4 mm shank could rotate at 400,000 min^-1 and cut grooves with depths of 30 µm to 40 µm on an aluminum alloy surface.

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This paper aims to evaluate the sustainability performance of machining operation of through-hardening steel, AISI 52100, taking into account the impact of the material removal process in its various aspects. Experiments were performed for dry and cryogenic cutting conditions using chamfered cubic boron nitride (CBN) tool inserts at varying cutting conditions (cutting speed and feed rate). Cutting forces, mechanical power, tool wear, white layer thickness, surface roughness and residual stresses were investigated in order to evaluate the effects of extreme in-process cooling on the machined surface. The results indicate that cryogenic cooling has the potential to be used for surface integrity enhancement for improved product life and more sustainable functional performance.

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Numerical error compensation is a cost-effective way to further improve the accuracy of high precision CNC machine tools. This paper discusses the major techniques for numerical error compensation on high precision machine tools. First, the high accuracy 2D holographic scale system and the dedicated measurement software are introduced. Then, the mathematical modeling of repeatable machine tool errors and the synthesis of volumetric error model are presented, followed by a description on the procedure of NC code modification. Error compensation experiments have been performed on a ballscrew driven machine tool and a linear driven machine tool. The experimental results show that numerical error compensation is generally effective on machine tools with both drive systems, while the linear driver system provides better dynamic performance for further improvement when the control precision is increased.

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