To investigate the influence of the WC and Co contents, the cutting of five kinds of cemented carbides was carried out with the PCD tool. Moreover, one of them was the cemented carbides whose binder was Ni, and the influence of the binder was also found out. The tool wear width and the cutting forces were measured, and the worn flank was observed. Summary of results are shown as follows. (1) It was found that the tool wear increased with increase of the Co content. (2) Not only the WC content but also the WC particle diameter influenced the tool life. (3) The adhesion could be found out in cutting every cemented carbides regardless of the content and composition. (4) The thrust forces were concerned with the flank wear.

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The machining forces, tool wear relationship of an Al-SiC (MMCs- Metal Matrix Composites) has been studied in this paper using K20 carbide cutting insert and results being discussed with artificial neural network. This paper presents the optimum machining condition of machining Al-SiC (MMC) by considering cutting force, power consumed, heat generated, MRR (Metal Removal Rate) and surface finish. The worn out tool is also analyzed under optical /Scanning microscope and the parameters are correlated with ANN (Artificial Neural Networks) by giving three input parameters and predicting three output parameters by training the network using back propagation neural network. The result provides some useful information.

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This paper reports on a new machining device developed for experimental study on machining property of hard-brittle material under external hydrostatic pressure. The machining device enables two dimensional machining tests under hydrostatic pressure, and in situ observation of a machining process by an optical microscope. Detail of structure of the device is reported in the paper. Some results of machining tests using a soda glass is also reported.

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A new approach to the improvement of cutting tool life by multilayering structure of tool materials is proposed instead of traditional one which uses mainly homogenous tool materials. The simplest multilayered structure of tool material, which is consisting of thin rake layer of conventional sintered carbide of type K10 and base material supporting the rake layer, was developed by using the hot isostatic press method (HIP). The study was aimed at determining proper base material and proper rake layer thickness. As a result, it was found in case of stainless steel machining that low carbon steel was the most suitable material as base material supporting the rake layer of sintered carbide within the materials tested in this study.

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In the present study, we have attempted to draw attention to the influences of pre-treatment and plating conditions on the cutting performance of cBN-coated tools. The pre-treatment evaluations are of the profile, the chemical cleaning and the bombardment conditions of the cutting edge. The plating condition evaluation concerns the influence of TiN and cBN plating conditions, respectively. Here, TiN plating is the pre-process of cBN plating. Moreover, using developed cBN-coated cutting tools, we carried out the cutting experiments for hardened die steel and austenitic structure stainless steels. As a result, it could be seen that the new cBN-coated cutting tools demonstrated effective performance for practical use in industrial fields.

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Usually the burnishing process is used to achieve small surface roughness. Surface roughness and residual stress also can be improved by the burnishing process. In this study, the burnishing tool that rubs on the machined surface with high rotating speed is proposed, and the enhancement of the material/mechanical properties on the surface is reported. The tip of the burnishing tool stirs within the thin surface layer under rather high strain rate in this process. Two kinds of tool tips were employed, which are the cemented carbide and PTFE (Teflon). Firstly, after the friction stir burnishing on 0.45% carbon-steel with the carbide tip, very hard layer over 800HV was appeared. The thickness of the hardened layer is 20μm〜30μm. Secondly, aluminum alloy 7075-T651 was burnished with the PTFE tip. Then the PTFE could be coated on the aluminum and the frictional coefficient of the surface was decreased. In addition, the surface hardness increased from 173HV to 215HV.

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Investigation on the drilling of two alpha beta titanium alloy series, Ti-6Al-4V and Ti-5Al-4V-0.6Mo-0.4Fe was conducted using uncoated WC/Co carbide drill. Tool life, tool failure mode and surface integrity were examined when drilling both alloys at various cutting speeds. Results showed that Ti-6Al-4V exhibited a more superior machinability property in the drilling tests when compared to the Ti-5Al-4V-Mo/Fe alloy system. The tool wear progression when drilling Ti-6Al-4V was significantly lower than that of Ti-5Al-4V-Mo/Fe. Non uniform wear and chipping on the drill were the main tool failure modes when drilling both alloys. Examination on the microstructure of the sub-surface of the drilled surface, indicated that both materials suffered significant plastic deformation at all cutting speeds.

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It is necessary to optimize the supply of oil mist and compressed air in the drilling case of long distance and small diameter using MQL (Minimal Quantity of Lubrication) method. In this study, firstly the total energy for deformation process and distributions of cutting heat were analyzed, then under the condition that a steady-state compressible adiabatic turbulent flow is assumed based on the ordinary MQL cutting conditions, the relationships of main parameters were obtained through the analysis of the calculation software, such as the thickness of oil mist, the flow speed, the temperature of the compressed air, and the average temperature of tool. Finally, the optimal volumes of oil mist and compressed air of MQL in drilling were presented for the cutting process.

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A new method of obtaining high-quality bamboo fibers with a machining center (MC), including a numerical control (NC) is proposed. This method allows for the manufacture of a wide variety of products. NC programs are designed according to a cutting theory based on a geometrical tool path for cylindrical work in bamboo pipes. The experimental results verified that the fiber length can be controlled by selecting the appropriate depth of cut along the bamboo fiber direction. Therefore, the desired fiber lengths can be obtained with consistently high accuracy using end milling with an MC.

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Ultrasonic machining (UM) is considered to be a very effective and relatively accurate way to engrave fine patterns and drill holes on brittle materials. This study aimed to investigate the feasibility of utilizing UM technique to fabricate parts of brittle materials in micrometers scale. Although brittle fracture (micro chipping) is the dominant material removal mechanism involved in the micro-ultrasonic machining process, poor surface roughness and deep penetrated cracks are the consequences if the machining parameters are not properly controlled. To ensure the quality of the generated surface and to improve the process efficiency, efforts have been made in this study to correlate the material removal mechanisms, surface integrity and tool wear involved in the micro-ultrasonic machining process to the machining conditions. The ultrasonic vibration frequency was kept at 20kHz and the feedrate was kept ranging from 0.1mm/min to 0.5mm/min. The effects of machining parameters such as types of abrasives, grit sizes and feedrate were investigated. It is found that by dividing the machining process into several stages, from coarse to fine, good surface integrity can be achieved without surrendering too much efficiency. Micro-components of various brittle materials such as glasses, Zerodure, fused quartz and silicon with dimension smaller than 100μm and surface roughness better than 0.15μm were successfully produced in this study.

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In order to extend the life of an artificial hip joint, it is necessary to reduce the amount of UHMWPE cup wear. One of remedies to reduce the wear is to improve surface roughness and roundness of the femoral head. Its surface roughness was successfully improved by ultra-precision finishing by means of abrasive in the previous paper. Furthermore, in order to improve roundness of femoral head, a machining model of the proposed method was developed. In this paper, to improve roundness of a femoral head, a nozzle feed speed planning method is proposed. The feed speed planning can be conducted by feed-forward calculation of machining amount according to the machining model. Nozzle feed speed control experiments showed effective improvement of the roundness, and thus the machining model and feed speed control method were verified to be feasible in practical use.

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YAG laser drilling is a very efficient method to drill fine holes on multi-layer aramid fiber composites. Aramid short Fiber Reinforced Plastics (AsFRP) consists of the high-strength and high-modulus fibers and the heat-resistant and corrosive-resistant plastics. In some cases, AsFRP laminates is required to be machined in order to apply it to the electronic parts, especially Printed Circuit Board (PCB). Therefore in this study, hole drilling of FRP laminates with YAG laser is carried out and its machinability is investigated. Irradiating time and flash lamp voltage are changed in wide range and both a hole configuration and an extent of Heat Affected Zone (HAZ) are examined. The optimal machining conditions of YAG laser for drilling fine holes on multi-layer aramid fiber composites are proposed. Furthermore, temperature distribution in AsFRP laminates and thermal shear stress between the matrix layer and the sheet layer are analyzed by Finite Deferential Method (FDM).

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Ion beam etching becomes more and more established in high precision surface processing for advanced optical, electronic and mechanical products. In optics fabrication IBF is able to overcome physical constraints of the conventional full lap and small tool abrasive polishing processes. This together with an accurate control of the removal rate results in an efficient correction of long spatial wavelength errors with almost no or minimum surface or subsurface damage, respectively due to the gentle beam surface interaction.

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To simulate cutting with abrasive grain in grinding, a random grain shape is modeled. The statistical distribution of the effective rake angles of abrasive grain is obtained by applying Usui's four models of kinematically admissible velocity fields. The material is removed in the case of complete chip or incomplete chip formation, but is not removed when wall of partial chip or plastic upheaval is generated. Next, residual stock removal by bulging, which occurs due to effect of cutting speed, is presumed. A critical undeformed chip thickness, under which chip forms with great difficulty, is introduced. As a result, a new model of surface generation process in grinding simulation is proposed.

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The grinding process is dissimilar to other conventional machining methods such as turning and milling. The difference between them is due to not only the cutting edges of the grinding wheel don't have the uniformity but also the edges act differently on the workpiece at each grinding. In spite of many researches past decades, describing the grinding action between the grinding wheel and the workpiece was not made clearly. So statistical models and computer simulations that could overcome the variety of the cutting edges were introduced. These complexities and difficulties of illustrating the grinding process also raised an obstacle to the optimization of the grinding process and to the verification of the interrelationship between the grinding parameter and the obtained grinding result. In present paper, the response surface models to predict the grinding power and the surface roughness in the external cylindrical grinding of the hardened SCM440 material and also to help the selection of grinding conditions by using the contour plot of the response surface were developed.

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The mechanical properties of the metal matrix composites (MMCs) are quite prior to conventional metal materials and they have possibility to be applicable to the wide scope of industrials. But there is insufficient to get fundamental information for machining these materials because of entering recent appearance. The study on machining these materials is essential. This study presented the grinding of the aluminum-based MMCs reinforced with SiC particles. The effect of the grinding parameters on the surface roughness and the grinding force was evaluated by design of experiments (DOE), and the second-order response surface models were developed based on the experimental data. Also the developed mathematical models composed of grinding parameters were optimized the genetic algorithm.

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This paper aims to estimate the fracture rotating speeds of grinding wheels by applying proposed mathematical model. Since the fracture of grinding wheels initially takes place in internal area of wheels, comparing the stresses due to the centrifugal force in this area to fracture stresses, fracture rotating speed of wheels can be estimated. From such a viewpoint, estimated results of fracture speeds coincide with the fracture test. As the results written above, it is clarified that fracture rotating speed can be estimated quantitatively by means of the proposed mathematical model.

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In the production process such as the semiconductor wafer slicing, the processing methods that used free abrasives wire saw are extensively adopted. However, these SiC grains after use are unfavorable from an environmental perspective, due to the fact that they become industrial wastes, and is also not very efficient. For these reasons, the development of the wire with fixed abrasives is required by industry. The major objects of this paper is to make the fixed abrasive wire saw apply to high cost production in semiconductor industries such as wafer slicing, and provide the industry with the effective processing parameter. Effects of processing parameters on the performance of fixed diamond wire sawing processes are investigated by using the Taguchi method for this design of experiment (DOE). The performance discussed in this paper includes machined surface roughness of the wafer, material removal rate and wear of the wire and kerf width. The processing parameters are grain size, wire tension, slurry, wire speed and feed rate. An L_9(3^4) orthogonal array, signal-to-noise (S/N) ratio are employed to analyze the effect of these processing parameters. The analysis of the result shows that the optimal combinations for good surface roughness are small grain size, high wire speed, and low feed rate. Wire speed and feed rate are positively related to material removal rate. The use of slurry results in a larger removal rate and larger wear of the wire. Furthermore, it was determined that the wire tension does not have any significant effect on the performance.

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OD-blades are widely used for precision slicing of hard and brittle materials such as ceramic and other new materials. Now, in order to improve OD-blade slicing performance, the development of slicing method for a high efficiency and accuracy has become important, and various research studies such as low-frequency vibration slicing have been performed. In this paper, we will discuss the principle of elliptical vibratory OD-blade slicing and the spindle mechanism produced elliptical vibration. Moreover, we will describe the effectiveness and practicability, as a practical method in the elliptical vibration slicing should be compared with those of the conventional method without using applied vibration. Several advantages of the vibration slicing method have been shown through basic experimental examination.

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This paper describes ultrasonically assisted grinding for injection die steel using diamond abrasive tools. In this study, a 3D positioning machine equipped with an ultrasonic spindle carried out grinding experiments. Generally, diamond tools cannot grind steel because of the terrible wear due to chemical reaction between diamond and steel. However, ultrasonically assisted grinding can make fine surface (roughness Rz is 0.4〜0.84μm) of die steel, without severe tool wear. Effects of tool feed rate, radial depth of cut and axial depth of cut were investigated.

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The use of the ultrasonic activated coolant improves ground surface roughness compared with the use of ordinary coolant. From the evaluation of change in the working surface condition, it has been clarified that the ultrasonic activated coolant suppresses loading and wheel wear, and keeps the working surface condition well. Since the ultrasonic vibration increases the kinetic energy per width of the coolant, the activation makes the coolant easy to overcome the airflow following wheel rotation and to reach the grinding point. Furthermore, the flushing effect of the vibration acceleration prevents the deposition and weld of chips.

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In this study, the applicability to surface grinding of the semi-cold-air, whose temperature is higher than that of the air in the conventional cold-air machining, is experimentally examined from the viewpoint in the cooling effect. By the result, the followings are found out: In case of semi-cold-air grinding, the cooling fluid is gas phase similar to the airflow following wheel rotation and then is mixed easily with the airflow. This makes the cooling effect at the grinding point and the working surface of grinding wheel steady and prevents thermal shock of grains. As a result, breaking and falling off of grains are suppressed, and then wheel wear decreases. Since this improves the finished surface roughness, the semi-cold-air can be said to be suitable as cooling-method for grinding.

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This paper proposes an innovative development of a grinding-hardening technology using an inert cryogen-liquid nitrogen. This technology not only integrates precision surface grinding with surface hardening treatment, but at the same time, produces satisfactory surface integrity of ground components, including compressive surface residual stresses and fine microstructure with a high hardness and wear resistance. The technology is cost-effective and because of the inert nature of the cryogen, the grinding process becomes environmentally conscious.

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The electricity rust preventive machining method is proposed to effective prevents the workpiece from rusting in the cylindrical grinding only with water. The workpiece as a cathode is protected from rusting by supplying the electric current through the water. This method leads to the ecology machining because the water without extreme pressure agents, mineral oils and so on included in conventional machining fluid. Therefore, this method saves much work in a treatment of stale machining fluid. In this paper, the electric rust preventive machining method is developed and investigated its application to cylindrical grinding.

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Fine silica abrasives wheel by electrophoretic deposition phenomenon, EPD pellet, was fabricated and applied to mirror grinding of 3 inches quartz-crystal wafers for the purpose of evaluating the grinding performance. Then. EPD pellets made a mirror surface and the final roughness was 6.5nmRy. The time required for making the mirror surface was less than 10min. No residual strain was found on the ground surface.

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New technology that enables to re-generate grinding tool on the machine which is utilized for a machining process without any tool exchange has been developed in this paper. The technology can provide resinoid and vitrified bonded abrasive tools on a mandrel. Rapid heating furnace is utilized for attaching and detaching the abrasive layer to the mandrel. The developed process can produce and keep grinding performance of a mounted grinding point, and also it can re-generate the resinoid and vitrified abrasive layer within 30 min.

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In order to make clear the effects of the uniformity in wheel structure on the grinding performance of vitrified CBN wheels, cylindrical plunge grinding experiments have been conducted using the two types of CBN wheel manufactured by a newly proposed method and a conventional method. The improvement of uniformity in wheel structure is effective to reduce the wheel wear and the increasing rate of surface roughness with the progress of grinding. The variation in distribution of grain cutting edges decreases by improving the uniformity of wheel structure and it inhibits the reduction of a cutting edge density during the grinding process. Consequently, the estimated tool life of uniform wheel, based on the roughness of finished surface, is about 1.8 times longer than that of conventional wheel.

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This paper describes the formation mechanism of finished surface in ultra-high speed grinding under a peripheral wheel speed higher than 200 m/s. Grinding experiments using a grinding machine tool equipped with an active magnetic bearing spindle have been conducted over a range of grinding speeds from 60 to 300 m/s. Moreover, grinding tests for producing some individual grinding grooves by using a grinding tool having multi-point CBN grits have been carried out to make clear the effects of grinding speed on the swell-out residuals formed along the both sides of the grinding grooves. From these experiments, we have confirmed that the ground surface roughness tends to improve with an increase of grinding speed and it is closely related to the decreasing of the swell-out residual rate by increasing the grinding speed.

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In recent years, it is essential to adopt the non-traditional machining technologies to produce the products getting a miniature and a precision in many application areas such as electric, electronic, automobile, aerospace and mechanical industrials. But in the cases of using them, the production rate is very low and the initial investment cost is more expensive. Thus there is a need to develop the new technology or the competitive machining method by improving capability of the conventional machine, tooling system and tool in itself. This study focused on selecting the proper CBN wheel and testing the performance for the groove grinding of LM guide blocks. The grinding conditions were changed and, in each grinding, the surface roughness of the workpiece and the radius of the curvature at the groove were measured.

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The wheel surface topography in the grinding process with vitrified CBN wheels have been investigated on the basis of 3-dimensional analysis using a multi-probe SEM, and the relationships between these results and grinding characteristic parameters have been discussed. Moreover, the change of the wheel surface profile during grinding has been evaluated by fractal analysis. There are two regions; an initial wear region and a steady-state wear region, in the grinding process. The cutting edge density decreases with an increase of stock removal during both regions. In the steady-state wear region, the micro self-sharpening phenomenon based on a micro fracture as well as an attritious wear of cutting edge occurs. The change of fractal dimension of wheel surface is closely related to the change of grinding force dominated by the wear behavior of grain cutting edges.

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This paper deals with the grinding characteristics of newly developed polycrystalline CBN (CBN-U) abrasives in creep feed profile grinding of nickel-based superalloys. Experiments for producing a V-shaped groove on a flat surface in one pass by creep feed grinding have been carried out using the new polycrystalline CBN-U and representative conventional CBN (CBN-B1) grits. When grinding with CBN-U abrasives, both radial wear and profile wear are less, and hence the grinding ratio is around 10 times higher than with the conventional CBN-B1 abrasives. Grinding forces in grinding with CBN-U are reduced by 20〜30% compared with CBN-B1. The CBN-U abrasive is suitable for the applications with a high dimensional accuracy in creep feed profile grinding for nickel-based superalloys, because it gives less profile wear, and hence better form retention, than conventional CBN abrasive.

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ELID (Electrolytic In-process Dressing) grinding method is possible to achieve ultraprecision smooth surface of hard and brittle materials. To obtain ultra smooth surface required such as micro lens and its metal mold, final polish process which required long time after conventional grinding process was necessary. ELID grinding method using an ultraprecision grinding machine tool will be very effective in reducing the time required for finial polishing process, In this paper, a fabrication experiment using this ELID grinding process was studied for Gradient Index (GRIN) lens. Especially, as a nano-precision micro-ELID grinding machining for GRIN lens, we studies on conditions of ELID grinding using a desk-top type 4 axes machine for development of GRIN aspherical lens with paraboloidal form, and GRIN prism.

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A demand for the mold of micro-lens is on the increase. As a system for the machining of micro-lens mold, a desk-top machine tool is being expected. But, when the grinding wheel with the small diameter is used, the ELID grinding method has a problem about the installation setting place of the negative electrode along the wheel. In this research, we developed a system to electrolyze the small type ELID grinding wheel. This system was realized ELID grinding processing without using the negative electrode along the wheel, for the purpose of machining of micro lens mold. That result succeeded in the development of the ELID grinding system which uses nozzle type electrodes (new electrode less ELID grinding metthod). Then, the processing using this system could get the mirror surface of Ra 8 nm without electric discharge scar. There was a small abrasion of ELID grinding wheel and abundant volume of material removed.

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This paper proposes an in-process truing method for metal-bonded diamond grinding wheels in electrolytic in-process dressing (ELID) grinding. In general ELID peripheral grinding, dressing voltage is equally supplied on the periphery of a grinding wheel, so that it is uniformly dressed. In contrast, in this study, an attempt has been made to supply dressing voltage in proportion to the wheel radius by the pulse width control in order to improve the roundness of the grinding wheel. For this purpose, a wheel profile monitoring system and a pulse controllable power supply were developed and the in-process truing procedure was designed. Finally, its effectiveness was verified experimentally.

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This paper introduces a schmidt lens manufacturing process, focusing on its axis-aymmetric aspherical surface manufacturing by synthesizing ELID grinding and arc-enveloped grinding method. For test experiment, an off-axis spherical surface was ground to obtain suitable grinding and ELID conditions. Then, the large axis-aymmetric aspherical concave and convex were ground on the developed grinding system using #325, #1200 diamond cast-iron bond wheels. Grinding characteristics such as attainable form accuracy, surface roughness were investigated.

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The ELID-grinding R&D activities on development of large optics for astronomical observatory and semiconductor fabrication, have been accelerated in these years. The authors developed the large aspheric nanoprecision ELID-grinders such as "L-uaoe-GIC", "N-aou-VEL", etc. for those purposes. In this paper, the authors introduce the examples of ELID-ground large mirrors and the new turning grinding method with the exclusive large and indexable rotary table which was newly developed specifically for efficient fabrication of large telescope mirror segments. The developed rotary table was successfully mounted on a large aspheric ELID-grinder. A new additional finishing process method was also devised on the machine.

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In this paper, we proposed a complex finishing process of MRF and ELID grinding and applied this method to nano-precision finishing for glass lens. ELID grinding, as pre-finishing, was employed to obtain high form accuracy and good surface quality in high efficiency. And then, MRF, as the final finishing, was used for improve furthermore surface quality and figure accuracy. Several sets of finishing experiments for sphere glass lens have been performed to verify obtainable surface figure precision and surface finish by use of this new synergistic process. Surface accuracy of the λ/18 nm P-V and surface micro-roughness less than 10 Angstroms for spherical lens were produced in high efficiency.

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In this paper, we proposed a complex finishing process of MRF and ELID grinding and applied this method to nano-precision finishing of silicon mirrors. ELID grinding, as the pre-finishing, was employed to obtain high efficiency and form accuracy, and then, MRF, as the final finishing, was used to improve furthermore surface quality and figure accuracy. Several sets of finishing experiments for silicon mirrors have been performed to verify obtainable surface figure precision and surface roughness by use of this new synergistic process. Surface accuracy of the 0.333μm peak-to-valley and surface micro-roughness less than 10 Angstrom for silicon mirror were produced in high efficiency.

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We have already proposed a new surface finishing process for metal molds by large-area electron beam (EB) irradiation in the previous report, and the effects of EB irradiation conditions on surface smoothing characteristics were investigated. As a result, the surface roughness could be reduced to less than 1μmRz in just a few minutes under a proper condition. Furthermore, the surface roughness of tilting surface close to 90 degree also could be well improved, which indicated that in the case of small simple shaped mold consisting of relatively small tilting surfaces, the smoothing of the whole surface is possible without moving and tilting the mold. In this paper, the surface characteristics of the EB irradiated surface were discussed by TEM observation, XRD analysis, and corrosion test. The surface structure changed by large-area EB irradiation, and consequently, the corrosion resistance of metal mold surface could be improved well.

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Productive finishing of very smooth surface for dies and molds are still in huge demand in industries. The conventional method to obtain such high quality finished surface has mainly relied on the manual polishing in most cases. In some cases, concentrated energy flows such as intense pulsed laser, electron and ion beams and pulsed plasma flows have been tried or applied to treat workpiece surfaces in industries and academies. In this study, a large diameter electron beam (LDEB) with a maximum diameter of nearly 60mm was applied to treat very quickly machined surfaces of hardened alloys. The preliminary experimental studies performed on two difficult-to-machine materials, WC/Co and NAK80, have shown that surface finish could be significantly improved under optimized beam application conditions while over irradiation could worsen surface quality. The effect of EB irradiation on residual stress was explored. The defects induced by LDEB irradiation process were also observed and discussed. The mechanism of the modification mechanism, especially the interaction between the electrons and the material has also been discussed.

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This paper proposes a new technology method to deposit tool electrode materials on workpiece in air, which breaks through the constraint of traditional EDM. At first, the basic discharge condition to realize this method is expatiated by heat transfer analysis between electrode and workpiece, and then the experiments were carried out on a die-sinking EDM machine tool. Based on a lot of experiments, the processing laws of micro EDM deposition is systematically and thoroughly studied by analyzing the main machining parameters' effect on deposit. Finally, adopting brass wire as tool electrode on the surface of high-speed steel workpiece, the micro cylinder (0.2mm in diameter, 7.35mm in height) can be achieved. And with a certain machining parameters, the deposit with spiral structure can be obtained. The properties of the deposit, such as structure, hardness and so on, were obtained by SEM, X-ray diffraction and other instruments.

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We have performed EDM of reverse-tapered microholes with a diameter of less than 100μm and a high rate of taper. Two methods have been tested for drilling a hole in a 50-μm-thick copper sheet using tungsten electrodes: one uses an electrode moving in planetary motion with planetary-motion diameter gradually increasing; the other employs an electrode bent at a high angle to its original axis. A hole 35μm in entrance diameter and 42μm in exit diameter was drilled by the former method and a hole 50μm in entrance diameter and 115μm in exit diameter was fabricated by the latter.

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This paper describes a die-sinking EDM simulation which can simulate the wear of tool electrode with sharp edges. The simulation is based on the discharge location searching algorithm where the discharge spot is determined by the rule that the probability of discharge occurrence is higher where the gap length is shorter. The necessary minimum node interval for simulating the wear of sharp edges was obtained, and a triangular mesh whose node interval decreases with decreasing the distance to the edge was generated. Simulation results indicate that rounding of tool electrode edges occurs due to the wider opposing area on the work piece per unit tool electrode area at the edge than on the flat surface.

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This paper describes the development of a simulation method to evaluate the accuracy of rough cutting in WEDM. The simulation program is a repetition of pulse discharge cycle based on the rule that the point where the working gap is shortest is selected as the discharge location. As some of the parameters used in the simulation are difficult to measure from experiments, they are obtained by solving the reverse problem by parametric programming. Investigations were carried out to evaluate simulation accuracy by executing simulation under various machining conditions after substituting identified parameters into the simulator. The simulation results agreed with the experimental ones qualitatively in terms of cutting groove shape, machining speed, and discharge frequency.

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In order to understand electrical discharge machining (EDM) phenomena, the characteristics of transition arc plasma in EDM were investigated. The arc plasma was directly observed with a high speed video camera. In addition, to learn more about arc plasma expansion, plasma temperature was measured by spectroscopy. The arc plasma temperature was obtained by measuring the radiant fluxes of two different wavelengths from the arc plasma and applying the line pair method. Furthermore, a new expansion model for EDM arc plasma was proposed based on the observations, and validated by comparing experimental and computed results of the discharge crater.

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This study aims to develop a new coating wire electrode for higher performance wire EDM instead of the conventional wires. The effects of coating material and its thickness on the fundamental machining characteristics are investigated, in order to understand the optimum structure, using a high-tensile steel wire coated with brass and zinc whose diameter is 200μm. The experimental results showed that the removal rate increased with the thickness of coated brass on the steel wire in WEDM with the brass and zinc coated steel wire. The SEM observation and the element analysis of wires after machining made it clear that the coated brass layer was easy to be removed when the thickness was small, and high tension could be loaded during machining when the thickness of coated brass was large enough to keep the stable machining performance. Furthermore, the effect of zinc coating on the removal rate became remarkable when the thickness of coated brass was relatively small.

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A new slicing method of monocrystalline silicon ingot using wire electrical discharge machining was proposed for high efficiency and high quality slicing instead of inner diameter blade or multi-wire method. The effects of supply method of working fluid and wire speed on machining characteristics were experimentally investigated. It is clarified that the immersion method is superior than the nozzle supply method and the wire speed over 200m/min is desirable for stable machining. Besides, mounting of wire sub-guide is useful for obtaining better kerf shape.

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