The purpose of this study is to clarify the influence of motion error of feed drive systems onto machined surface generated by ball end-mill. In order to achieve the purpose, cutting tests and simulation of hemisphere shape were carried out. As a result, it is clarified that the innermost motion paths to the work piece are copied onto the finished surface. For example, even if a stepwise error exists on the motion trajectories, the error is not copied onto the finished surface when the surface is generated by bi-directional tool paths.
The study presents a novel approach to the fabrication of a biomedical-slide mold for in-situ producing convex platform quantitative cell-counting slides made of PMMA. The process incorporates three important procedures: 1) the development of a high-precision hybrid dual-spindle CNC machine tool; 2) the formation of a boron-doped polycrystalline composite diamond (BD-PCD) wheel-tool on the machine tool developed; and 3) the cutting of a multi-groove -biomedical-slide mold array using the formed diamond wheel-tool in-situ on the developed machines. The factors influencing formation of the wheel-tool and generation of the microgroove array are discussed in detail.
This paper presents an alternative way of producing a hole by using a helical milling concept on a CFRP/Aluminium stacks. Fiber delamination and burr formation which is the main defect occurred during hole making process on CFRP and aluminium were investigate throughout an experimental study. This study focused on the helical milling technique using four types of end mill geometries to produce a hole. Various levels of cutting parameter such as cutting speed, feed rate and depth of cut have been chosen to observe the effect of thrust force, temperature, delamination, burr and surface roughness. The result will be used to determine on which end mill geometry and cutting parameters give the best performance.
The purpose of this study is to improve real-time compensation of machining errors caused by deflection of two-flute end mills with small diameter like ball end mills. For this purpose, relation between tool deflections at cutting point and forces applied to cutting point was investigated, and then the measured machining errors was compared with the machining errors estimated from measured cutting forces. As a result, the estimated machining errors approximately coincided with the measured machining errors but the difference between the estimated and measured machining errors was larger at smaller axial depth of cut in down cut and it was larger at larger axial depth of cut in up cut.
Titanium alloys are excellent materials, but typical processing resistant materials. Laser forming is expected as new method of metal sheet forming, especially shape tuning. Laser forming can bend the Titanium sheets without the brittle cracks. The bended angle at free edge was different from the angle at center part, even if same laser processing conditions were applied. This research simulated deformation behavior at the free edge to investigate the influence of the free edge. It was confirmed that the ratio of the irradiated energy to the heat capacity of a free edge related to the bended angle.
The propagation of thermal stress in sheet glass during single pulsed laser irradiation was clarified using a one-dimensional model. A thermoelastic equation based on an equation of motion was applied. In the case of a 0.1 μs pulse width, a thermal stress cycle of propagation, reflection, propagation, interference, and separation was revealed. Upon the reflection of stress wave at the free ends, the polarity of the stress change. Alternating stresses of approximately 0.5 MHz appeared inside the sheet glass. Because a crack may propagate in the glass as a result of the stress, there is a possibility of high-cycle fatigue. It was found that the thermal stress generated by single pulsed laser irradiation exhibited wavelike properties.
Copper is widely used as an electric wiring material in electric and electronic industries because of its high electrical conductivity. However, high thermal conductivity of copper leads to the rapid diffusion of heat, which results in difficulties in micro-welding. Therefore, micro-welding of copper by a pulsed green laser of 532nm was investigated to control the heat input in micro-spot. 1.0kW peak power at spot diameter less than 200μm could perform a keyhole welding of 1.0mm thickness copper plate. Penetration depth increased with decreasing the spot diameter and increasing the pulse duration. The porosities could be reduced by extending the pulse duration and controlling the pulse waveform.
Micro-drilling characteristics of SiC by harmonics of Nd:YAG laser were experimentally investigated in the viewpoints of wavelength and the surrounding gas type condition. Moreover, plasma and processing behavior were observed to discuss micro-drilling characteristics of SiC. The debris was removed away in the opposite direction of laser beam along the flow field generated by laser irradiation. The behavior, the spectrum and the intensity of laser induced plasma were influenced by the surrounding gas condition. The appearance of plasma affected the surface integrity at the circumference of drilled hole, and the surface integrity could be improved under the reduced pressure condition.
In laser cutting and drilling process, molten material was scattered as spatters, which deteriorate the surface integrity of workpiece due to the thermal damage. It is expected that the control of assist gas flow can reduce the adhesion of spatter. In order to investigate the improvement method of thermal damage due to the adhesion of spatter, it is required to clarify characteristics of spatters. Therefore, the collection and the analyzing method of spatters with high-speed video cameras in the laser micro-drilling were developed, and characteristics of spatter movement were numerically investigated by CFD analysis.
This paper proposes a novel process to achieve high efficiency die and mold machining technology. The process consists of laser milling for rough process and micro end milling for finishing. In the present paper, reasonable pulsed laser irradiation method is investigated in advance. Some fundamental experiments were carried out to clarify influences of laser irradiation conditions on surface quality and material removal rate in case of hardened die steels for workpiece material. As a result, reasonable laser irradiation conditions including shorter pulse duration and higher peak power irradiation were derived.
Internal processing of glass was conducted by a femtosecond laser. The laser is irradiated repeatedly while the distance between pulses was kept constant. When the time interval of pulses was comparatively long, a narrow and long triangle-like pattern was obtained. On the other hand, a feather pen-like pattern was generated when the time interval is relatively short. It was estimated that the former pattern is obtained by two-photon absorption and the latter pattern is generated also by the temperature dependence of linear absorption coefficient due to heat accumulation effect. Validity of these estimations was confirmed by simple heat conduction analysis.
The inside of the molding die fabricated by additive manufacturing can locate cooling channels efficiently. However, the internal face of cooling channels has the problem that face roughness of the cooling channels is not uniform due to the partially melted powder. In this research, the method of finishing the internal face by free abrasive grain is proposed. As a result, the internal face roughness in the cooling channel was improved significantly by the removal of the partially melted powder. The cooling channel of smaller diameter has high processability due to the high velocity of flow by passing through the channel.
This paper deals with the formation of re-solidified layer on dental hard tissue by irradiation of a pulse Er:YAG laser beam. Extracted human enamel is used as a specimen, and titanium dioxide powder is applied to the surface of dental hard tissue as the absorbent. Er:YAG laser beam is led to the specimen with an optical fiber. The influence of powder thickness and laser condition on re-solidified layer is investigated experimentally. The result showed that the re-solidified layer was formed on the surface of dental hard tissue by irradiation of Er:YAG laser beam, and the sufficient layer thickness of titanium dioxide powder is 10-15 mm for formation of re-solidified layer.
Incubation effects in the material removal and the surface integrity of LN are investigated for damage-free, precious steric micro processing from the results of preliminary micro processing experiments of laser ablation via the multi photon process with controlled incubation effects in scanning laser multi pulse shots. Advisable process conditions are larger N and smaller for control of the incubation effects.
Fixed abrasive technology has been required. Plane honing is one of the effective fixed abrasive technologies for processing semiconductor wafers. The paper presents a method to simulate the process of plane honing on the basis of statistical analysis for grinding. To treat a pressure-controlled process, the reference curves of segments were introduced and removal material amount of each segment was assumed as constant. Plane honing experiments were then conducted and the results agreed qualitatively with the simulation results.
In this study, a pulsed Nd:YAG laser beam is used as a non-contact thermal dressing tool for a metal bonded diamond wheel. In order to efficiently remove the bond material, it is necessary to direct air on the spot irradiated by the laser so as to blow away the molten binder. The new integrated laser-air head makes it possible to make an appropriate chip pocket depth with less residual re-solidification layer of bond material. The grinding experiments of the hot-pressed SiC reveals that the laser-dressed wheel has somewhat better grinding performance than the conventional rotary dressed wheel.
The wafer grinding by use of a diamond grinding wheel is required to create a high-quality wafer surface in a short time. In general, it is known that high-quality wafer surface can be obtained by reducing the amount of material removal per abrasive cutting edge. In other words, an excellent surface quality is obtainable by an increasing in the areal density of effective abrasive cutting edge on the grinding wheel working surface. In this study, we aim to understanding of the three-dimensional distribution of abrasive grains on diamond wheel working surface, from both theoretical and experimental aspects, and evaluation its influence on the grinding performance.
Recently, fine ceramics are used at various fields for its mechanically, electrically and chemically useful property. However, processing condition cannot be used for conventional ceramics by changing of its property. In this study, the small holes open processing in the fine ceramics newly developed based on zirconia ceramics for mold instead of metal is examined. On the experiment of this study, grinding wheel is used and grinding force for each direction is measured by multicomponent dynamometer by finding a suitable processing condition in high precision and high efficiency.
In superfinishing, it is difficult to monitor the transitions of machining state during machining process. Therefore, to optimize the machining conditions, it takes a lot of time because many workpieces are machined as a trial. To solve this problem, it is necessary to monitor the transition of the machining state during process. In this study, an advanced in-process monitoring method of machining state in superfinishing is developed. We confirm that the transition of machining state can be monitored by calculating the machining force ratio during machining process experimentally.
To expose the material removal mechanism in ultrasonic assisted grinding (UAG) of SiC ceramics, the deformation features of SiC ceramics in ultrasonic assisted scratching (UAS) tests were investigated and compared with those in conventional scratching (CS). The results revealed that the scratching force varies periodically and the scratching trace appears to be sinusoidal in UAS. It was also found that the scratching groove generated in CAS is deeper than that in CS and the sizes of lateral cracks are increased owing to the impact of the tool generated in UAS process.
This paper aims to evaluate small diameter diamond grinding wheel surface topography in ultrasonic assisted grinding (UAG) process quantitatively and demonstrate the effect of the topography on grinding characteristics. In this study, a scanning electron microscope with four electron probes (3D-SEM) was used for 3D observations of the wheel working surface in on-surface UAG process. From these results, good wheel surface maintained in UAG process have been evaluated quantitatively by the number and the area of cutting edges. Additionally, these results are closely concerned to the low grinding forces and manufacturing of mirror workpiece surface easily, respectively.
In machining of carbon fiber reinforced plastic (CFRP), machining heat aflects an interface with matrix resin and carbon fibers to lead delamination of carbon fibers. In this study, the measuring technique of the grinding temperature of grain at grinding point and that at wheel contact area of CFRP is developed based on the Seebeck effect, and influence of grinding atmosphere, in which dry grinding, wet grinding supplying water-soluble coolant or that supplying liquid nitrogen, on grinding temperature of CFRP is experimentally investigated.
This study aims at developing the turning system that enable even beginners to do the easy and safe operation for turning machine by using a haptic device as a new operation interface. In this study, the system was developed to teach the machining movement for models in the virtual space by using the haptic device. The taught movement is output as the movement of turning machine, and the actual machining is performed. As the result of some experiments, the usefulness of developed method was actually confirmed.
Unskilled engineers have difficulty determining the appropriate end-mills and end-milling conditions for materials and shapes designed by CAD, even though end-mills are specifically designed for various purpose such as milling at high speed and milling of difficult-to-cut materials. Ball end-mills are usually the most suitable for die and mold milling since they can be easily adapted to workpieces with various complicated shapes. We previously reported an end-milling condition decision support system ("catalog mining system") that applies data-mining methods from square end-mill tool shape parameters listed in a cutting tool catalog. Our aim was to extract new knowledge by applying data-mining techniques to a tool catalog. We used both hierarchical and non-hierarchical clustering methods and principal component regression. We focused on the shape element of catalog data and visually clustered ball end-mills from the viewpoint of tool shape, which here meant the ratio of dimensions, by using the k-means method. Expressions for calculating end-milling conditions were derived using the response surface method. We have now conducted end-milling experiments using ball end-mills and compared the calculated values with the catalog ones to validate end-milling conditions derived from catalog-mining system.
Edge imperfections are often introduced on workpieces due to plastic deformation during machining. These imperfections are known as burrs. Since the deburring operation is costly, the control of burr formation is a research topic of great significance for industrial applications. This study introduces a system that focuses on the prediction of burr positions and dimensions in the end milling process as a preventive measurement method. This system is based on burr formation models, analytical cutting force models, and experimental validation. Both the predicted and experimental results were found to agree in some cutting conditions.
Current CAM systems are difficult for unskilled engineers to use and are still labor-intensive tasks because of too many conditions to select. In this research, the automatic machining process deciding system was developed. The system analyzes the shape of a 3D-model and extracts manufacturing features considering combinations of feature regions. Each manufacturing feature has the corresponding machining method, so the system decides machining method following them. The system also selects cutting tool considering the shape of manufacturing features and decides machining sequence considering combinations of machining tool. This system enables unskilled user to achieve more efficient machining process.
NC machine tools generate desired shapes by relative motion control between tool and workpiece. Since several tool paths exist in machining products with NC machine tools, it is difficult to plan the suitable motion path for the machining. This study investigates the energy consumption of feed drive systems of NC machine tools during the machining operation. In this study, an evaluation method to predict the energy consumption for a given motion path patterns is proposed. The results of this study confirmed that the proposed method can evaluate the power efficiency of each motion path based on its energy consumption.
In order to establish responsive information from design to support an autonomous machining operation, the generative automated process planning is proposed. The proposed concept has two main parts, a TRV extractor and a machine process planner. In this paper, pre-defined total removal volume (TRV) is used to recognize features which constitute the volume that needs to be removed in shaping features. In the process planner, the machining processes are planned using TRV geometry characteristics. In this proposal, vertical machining center is used for preliminary study of the applied concept. The robustness of the methodology is tested using several prismatic parts previously tested in related research on process planning.
A simulation model is proposed in the paper to estimate and to verify the geometry deviations of the machined surfaces in the machining processes of CNC machining centers and single point tools. The model proposed here represents the boring processes based on both the shape generation motions and the cutting tool geometries. The individual motions are mathematically described by 4 by 4 transformation matrices including the kinematic motion deviations. Emphasis is given to the modeling and analysis of the machining process of the single point tools.
This study deals with the development of an automatic system for measuring and evaluating the thickness of free curved plates, called Orthros. We proposed a method to generate a measuring path with high continuity of the measuring postures by using a quaternion to represent a change in posture with an interpolation algorithm, called squad. In this paper, a new method is proposed to determine the positions and postures of the representative points for interpolation that affect continuity of the measuring path. The validity of the proposed method was confirmed using evaluations of the continuity of a path according to changes in the joint angle of a robot.
This research describes an on-machine form measurement system of high precision ceramics parts. This system consists of a grinding machine and a laser displacement sensor. By using two horizontal axes of the grinding machine with sub-micrometric motion accuracy and the high precision laser displacement sensor which is mounted on the grinding machine, three-dimensional continuous form measurement with sub-micrometric accuracy can be realized in non-contact condition. In order to evaluate the stability and motion accuracy which influence the measurement accuracy of the system, the experiments to estimate stability and motion accuracy were conducted. And the form measurements were conducted.
The nanopipette ball probe is introduced for measuring three dimensional forms of micrometric structures. The shaft of the probe is made of glass pipette which has low Young's modulus in order not to damage the measurement object, and a micro glass ball is fixed to the tip of the shaft to measure in all directions. In addition, shear-force detection has been applied to detect approach of measurement object with low measuring force. In this paper, the basic property of the probe is evaluated, and dimensional form measurement is demonstrated by using the probe.
This paper presents a new measurement system for on-machine form measurement of surface edges. The system is composed of a laser displacement sensor and a cantilever, on which a mechanical stylus probe would be mounted. The displacement of the cantilever probe is measured by a laser displacement sensor. Tip radius of the stylus probe is smaller than the diameter of the laser spot and the cantilever is fabricated with a material with a low spring constant. The proposed system satisfies both the large measurement range and low measurement force, while it can be applied to on-machine measurements.
This paper describes a laser angle sensor with a femtosecond laser based on the laser autocollimation method. Instead of a semiconductor laser in the conventional laser autocollimation sensor, a femtosecond mode-locked laser is employed as the light source. The collimated beam from the femtosecond laser is projected on a target reflector. The reflected beam is received by an autocollimation unit, which is optimized for femtosecond mode-locked laser. Since the carrier frequency of the femtosecond laser is stabilized by an external rubidium frequency standard, the sensor sensitivity can be improved. The prototype sensor has been designed and fabricated, and the results of the evaluation experiments are presented.
This paper presents a new method for measuring straightness with high accuracy and wide range. A proposed method is based on a simple principle; motion errors are detected with angle sensors, and these errors are directly used for compensating the measurement errors. In this study, straightness measurement experiments are carried out for evaluating the performance of the proposed method. In consequence, the measurement error of the surface profile is 0.63μm with a measuring length of 160mm. Therefore, the experimental results confirm that the method can measure various surfaces with high accuracy.
Microfabricated structures continuing to shrink with development of nano-technology, an inspection technology which can be applied to sub-micrometer features is getting important. A super-resolution inspection method beyond the diffraction limit using the structured light shifts is one of the potential inspection techniques. In this article, in order to expand the application of this optical super-resolution inspection method to coherent imaging condition, a novel coherent imaging algorithm based on the special three-light-flux standing wave structured light was proposed. Numerical simulation analyses confirm that proposed method can be applied to coherent imaging condition such as general microstructured surface.
The Herbert hardness tester is a typical pendulum-type hardness tester. Hardness is measured based on the swing angle of the pendulum in relation to the specimen. In the present study, hardness was measured using a Habara-type Herbert pendulum hardness tester with a modified measurement system and a Brinell hardness tester, and we investigated the effect of each condition, such as the indenter radius of the pendulum tester, the swing cycle, and the surface roughness of the specimens. Moreover, we discussed the relationship between damping hardness and conventional Brinell hardness, and the Brinell hardness was found to be obtainable from the damping hardness.
A visualization method for micro flow using light interferometer to sense the change of refractive index in flow is proposed. In particular, the concept of this method is that noise is added to enhance the sensing resolution based on stochastic resonance. The feasibility of this method was tested by a fundamental experiment. By using scattered light derived from Brownian particles as the noise source, instead of refractive index change, the given displacement of 10nm in optical length difference was distinguished successfully with even 4-bits camera.
This paper describes the compensation methods of a commercial capacitive-based electronic clinometer for precision measurement of inclination with an accuracy of 0.007°. To measure the inclination more precisely and quickly, the linearity error of the sensor output was compensated based on the inclination angle and sensor output curve. It was confirmed that the residual linearity error after a third-order fitting was less than 0.007°. A compensation method, which is referred to as the delay time method for shortening the stabilization time of the sensor was also discussed. Experimental results have shown the possibility of reducing the linearity error and achieving the quick measurement with the delay time method.
This paper presents a novel method for the measurement of the contact potential difference (CPD) and material distribution over the sample surface using scanning electrostatic force microscope (SEFM). Since the intensity of electrostatic force generated between the probe and the sample surface is relied on the differences of the CPD, the CPD can be calculated by using the frequency shifts of the probe oscillation when two different bias voltages are applied between tip and the sample. The detection sensitivity corresponding to the experimental conditions has been confirmed by simulation. In addition, the basic characteristic of the CPD measurement system has been evaluated.
For measuring the surface profile of many micro-optical components with complicated shapes, which are made of non-conductive material, the electrostatic force microscopy (EFM) was recommended. The relationship between the polarization force and the tip-to-sample distance was analyzed based on dielectric polarization theory. The prototype of the scanning electrostatic force microscopy was built. The force curves of different samples with different materials and surface shapes were detected by the EFM prototype. Both theoretical analysis and the experimental results demonstrated that the EFM system can be used to measure the surface profile of non-conductor.
A fabrication process of a thermal element, which would be used as a contact sensor in the concept of defect detection on smooth surfaces, has been designed. The thermal element, which consists of thin-film resistance, would be used to capture small amount of frictional heat generated at the contact with nanometer-order defects. Therefore, feasibility of the designed process has been verified by developing a first prototype of the thermal element, while considering its thermal sensitivity. Experimental results revealed that the fabricated thermal element is functional for detecting small amount of heat on the order of several-ten microwatts.
The poor bonding strength between dental zirconia implants and resin luting cements limits the practical applications of zirconia ceramics. Better wettability is a prerequisite for strong bonding strength. A new surface treatment technology was proposed to improve the wettability of zirconia by creating micro/nano surface textures. The technology was referred as ultrasonic-vibration assisted slant-feed grinding (UASG). Three ultrasonic vibration modes were employed for surface texturing by UASG and different types of micro/nano surface textures were fabricated successfully. The contact angle measurement revealed that these micro/nano textured surfaces had better surface wettability than that of surfaces fabricated by conventional grinding.
The initiation and propagation of cracks generated on a work surface during ultrasonic machining (USM) were simulated using smoothed particle hydrodynamics (SPH). Different abrasive materials, tool materials and abrasive sizes were used in this simulation. The distribution and size of the calculated cracks are strongly influenced by these process conditions. Also, experiments were conducted to observe the cracks remaining on a work surface by drilling deep blind holes in soda-lime glass. According to the simulation and experimental results, using tools with a lower yield stress, slurry made of softer and smaller abrasives can decrease the crack size. This work could be very useful in studying the machining performance of the USM process.
A non-rigid micro/nano scale cutting mechanism that is capable to fabricate micro-grooves in a surface of some square centimeters with a constant cutting depth and even on inclined surfaces has been developed. This mechanism is based on the control principle of the nano-cutting technique using an Atomic Force Microscope, where a cantilever with a diamond tool attached at its free edge is used to remove the material from the workpiece. Using an optical lever, the angular deformation at the tip of the cantilever is measure, allowing us to grasp the total cutting force involved during the machining process.
When a Y-TZP workpiece is heated to 600 °C and is machined with a cutting tool, the shear stress on the workpiece does not induce transformation of the crystal. In this study, a precision cutting method for sintered Y-TZP, namely, ultraviolet-laser-assisted machining (UV-LAM), is proposed. This method benefits from a decrease in the fracture toughness of Y-TZP at high temperatures and its good optical absorption in the UV range.
A lot of micro machining has been reported in seeking for best condition and attempts in revealing new methods and materials. Tool size and contact surface became smaller as the materials have excellent mechanical properties and parts produced are in micro size level. In studying the processing parameters and their effects to processing characteristics, temperature measurement is crucially important. However, limited size of working area and temperature changes time frame has lemmatized the applicable temperature measuring tool. This study demonstrates an alternative method in obtaining and validating work piece temperature distribution irradiated using pulsed wave laser in Laser Assisted Micro Milling (LAμM).
Carbon-fiber-reinforced plastics (CFRP) are known as a difficult-to-cut material. We propose the use of a flexible circular saw in a novel machining process for CFRP plate cutting. Unlike a typical circular saw, it can cut curved lines by deflecting the saw body into bowl-like-shape to fit a target curved line. In this paper, we conducted a cutting test on CFRP plates using the flexible circular saw to evaluate its machining characteristics. As a result, the flexible circular saw showed excellent cutting properties compared with endmill cutting. Moreover, it was shown that the flexible circular saw could cut CFRP plates at a high feed rate of more than 3000 mm/min.
In this study, Frictional Stir Burnishing (FSB) was applied to 0.45% C steel plate using a tool with a flat tip. As the result, an enhanced layer of high hardness (650 HV) was formed on the material surface. The surface roughness was large (Ra 1.2 μm), and tensile residual stress (300 MPa) was induced on the processed surface. The FSB-processed surface was further machined by face milling to reduce the roughness, and burrs on the FSB-processed surface were effectively removed. It was confirmed that the surface roughness (Ra 0.2 μm) was reduced, and compressive residual stress (-400 MPa) was induced on the processed surface without decreasing the high hardness (650 HV) within the enhanced layer.
This study investigated the influences of cutting speed and rake angle on the cutting characteristics of natural rubber experimentally in order to explore the applicability of high-speed cutting of natural rubber. The experimental results reveal that the apparent stiffness of natural rubber around the shear zone is raised by high-speed cutting. This is attributed to the increase in the viscous drag. Much higher cutting speed, however, deteriorates the accuracy of the machined shape, especially when the cutting speed exceeds 70 m/s. This can explain due to the development of the shock waves in the shear zone.