Multidisciplinary study and practice of high-precision engineering, metrology, and manufacturing have made a direct contribution to industrial and economic development in the world, providing new value creation and enhancing productivity and product quality. This special issue focuses on the latest studies in the field of precision engineering. The special issue especially features advanced technologies in the manufacturing process, metrology, machine tools, machine elements, and nano/micro mechanisms. Besides these technologies, to enhance reliability and safety in the production processes, there is a need for usability and functionality based on IoT-related technology, which is represented by Industrie 4.0 or the Industrial Internet. Therefore, many researchers have now begun to focus on cyber-physical production systems (CPPS), which can detect anomalies and self-optimize the production process by comparing actual results extracted from sensors and simulation results. From this viewpoint, advanced research related to CPPS, such as simulation-based technique, sensor-based technology, and in-depth understanding and modeling of the manufacturing process, is covered in this special issue.
In this special issue of IJAT, there are 14 research papers on precision-engineering-related topics as mentioned above. The papers, revised and extended according to the editors’ request, were originally presented at the 17th International Conference on Precision Engineering (ICPE2018), held in Kamakura, Japan, in 2018. We express our sincere thanks to the authors and reviewers for their meticulous work in helping publish this special issue. We hope these articles will encourage further research on precision engineering.
Completely automated assembly sequence planning for control panels is proposed. The proposed algorithm generates the manufacturing bill of material for the assembly processes and total assembly sequence. The algorithm integrates the knowledge of assembly process into a near optimum assembly sequence generation.
Sintered tungsten carbide which has high hardness and high heat resistance, has been widely used in molds and dies. Research on the development of a cutting technology for sintered tungsten carbide (sintered WC-Co alloy) has been pursued mainly with the use of a turning process. We focused on building an efficient milling method for sintered tungsten carbide by using diamond-coated ball end tools, and have investigated their basic properties under specific cutting conditions. This study extends our previous work by enhancing cutting distance in the milling of sintered tungsten carbide, especially that with a “fine” WC grain. The surface roughness of cut workpieces is evaluated from the point of view of the quality of surface roughness. A series of cutting experiments under different cutting conditions were carried out, and the possibility of deriving a suitable cutting condition for the ball end milling of sintered tungsten carbide is discussed.
This study deals with shoulder cutting phenomena in micro-end-milling of hardened die steel. Demand for micro-end-milling for products in the medical, optical, and electronics industry is increasing. However, in machining with a small diameter end mill that has diameter of e.g., 0.5 mm, the rigidity of the tool itself is low; therefore, cutting conditions must be set to low values to achieve stable machining. We revealed that cutting phenomena became unstable because the end cutting edge was damaged early in shoulder cutting. Therefore, we experimentally prepared a left hand helical tool with a right hand cut to perform complete processing by improving the strength of the end cutting edge. Cutting experiments were carried out while measuring cutting force and observing cutting phenomena, end cutting edge, and machined surface via scanning electron microscopy (SEM). We determined the effects of such tools on fundamental phenomena in shoulder cutting with a small diameter end mill. The rake angle of the tool was improved based on experimental analysis of the damage mechanism of the cutting edge in the shoulder cutting. A result of the examination to investigate the influence of the difference in rake angle on chip evacuation showed that the chip discharge direction was affected by the rake angle; when the angle is blunt, the chips were discharged upward, and the chip discharge performance improved.
A contour line model for end milling simulation, which realizes high-speed arithmetic processing by reducing memory usage, is proposed. In this model, a 3-dimensional shape can be expressed by superimposing the contour lines of the cross-sections obtained by dividing the workpiece along any axial direction. Therefore, the memory usage is reduced compared to a Z-map model or a voxel model as the interior information of the object can be eliminated. The contour line model can also be applied to complicated shapes having overhangs. Furthermore, cutting volume can be calculated from the interference area enclosed by two contour lines of the workpiece and the tool cross-sections. The workpiece shape can be changed by eliminating the interference area. In the contour line model, cutting force can also be predicted with an instantaneous rigid force model using the uncut chip thickness for each cutting edge from the positional relationship between the interference area and the cutting edge. To validate the proposed model, cutting experiments were conducted, which confirmed that the predicted machining shape had good agreement with the actual machined shape. Furthermore, it was confirmed that the cutting force can be predicted accurately.
Optimum experimental conditions, that realize good surface roughness in feed direction, for a radius end mill against some inclined surfaces is obtained by the Taguchi method. Some cutting features due to the unique shape of the radius end mill are revealed via the degree of influence of various factors, which are calculated by the Taguchi method, and the geometric relationship of some contact states of the tool. The experimental conditions include cutting type, spindle speed, feed rate, depth of immersion, inclination angle, and corner radius. The results revealed that the contact states are highly significant, and can be categorized into three types. Furthermore, bottom and corner edges must be contacted simultaneously in order to obtain good surface roughness.
An angle sensor can be used to evaluate profiles without any shape references. We regard it suitable for evaluating a large profile and consider a gyro as an angle sensor for evaluating a profile larger than 100 m with an accuracy of better than 1 mm. A gyro can evaluate profiles without restrictions in span or direction; however, angles detected by a gyro typically fluctuate unacceptably for our purpose. We demonstrate that periodical reversal measurement by flipping a gyro is effective in reducing the effect of the fluctuation. Then, we rotate the gyro for continuously realizing the reversal, where the angles of the gyro’s rotating axis against the earth’s rotating axis can be derived without being affected by the fluctuation, and can be used as an angle sensor. Here, we consider a new method using gyro signals rotating around four orthogonally aligned axes. This can improve the accuracy of the derived angles by eliminating the effects of the gyro’s scale factor as well as the fluctuations.
This paper deals with the grinding energy distributions in wheel-workpiece contact zone and the wear behaviors of grain cutting edges in cBN deep grinding. By measuring the tangential grinding force distribution in the grinding zone, the grinding energy distribution form could be approximated to be triangular. However, the grinding energy distribution forms changed a little occurring workpiece burn. The wear behaviors of the grain cutting edges were observed by a Scanning Electron Microscope (SEM) and quantitatively evaluated in terms of attritious wear flat percentage. It is shown that the variation of the grinding energy distributions has an effect on the cutting edge wear characteristics.
The high-accuracy manufacturing of optical requires highly integrated ultraprecision cutting technologies. However, all sorts of small errors adversely affect machining accuracy because of the miniaturization and complexity of objects. Among these errors, slight setting errors critically impact machining accuracy because it is difficult to place a cutting tool accurately on a ultraprecision machine tool. The authors have conducted multi-axis control ultraprecision cutting based on tool setting errors compensation. In this compensation method, the workpiece must be removed from the machine tool after test cutting to measure grooves to detect actual tool positions and to calculate setting errors. However, after the workpiece is removed, it cannot be perfectly replaced on a ultraprecision machine tool. This makes it difficult to automate setting errors compensation. In order to solve these problems, tool positioning must be detected without removing the workpiece. Therefore, in this study, a novel compensation method is developed by means of non-contact measurement with a laser imaging device. Furthermore, in order to improve compensation performance, a laser imaging device is calibrated on an ultraprecision machine tool. The proposed method enables direct detection of actual tool position and calculation of the tool centerpoint coordinate on the machine coordinate system. By modifying an NC program, the tool setting errors can be finally compensated. The feasibility of the proposed compensation method is verified by conducting experiments of creating grooves.
Hydrostatic bearings are important elements that directly affect machining accuracy in machine tools. Although hydrostatic bearings using water can reduce environmental influence compared with those using oil, they have low rigidity and damping properties. By investigating the properties of water used for working fluid of hydrostatic bearings, there is a possibility that the characteristics of hydrostatic bearings using water can be improved. Therefore, in this study, the relationship between the properties of water used as a working fluid of hydrostatic bearings and the characteristics of bearings was investigated. For this purpose, a hydrostatic bearing characteristics evaluation system using water was constructed. The characteristics of hydrostatic bearings were examined by varying the components and temperature of water. The experimental results show that the composition and temperature of working water affect the performance of water hydrostatic bearing.
New energy saving methods are required in the industrial sector to address global climate change and resource depletion. Carbon fiber reinforced plastic (CFRP) has attracted considerable attention as a structural material that can improve energy efficiency by weight reduction. The application of CFRP to machine tools has already been realized; however, the dynamic characteristics of the position control system for CFRP machine tools have not been investigated. In this study, the mechanical properties affecting the positioning performance were experimentally evaluated using a rotary stage that could be switched to different structural materials. This study can be useful as a guideline for position control systems and the mechanical design of a CFRP stage and contribute toward achieving higher energy efficiency.
This study proposes a novel microprobing system for the surface detection of the side wall of micrometric scale workpieces based on the detection of the local surface interaction force. A spherical tip-shaped glass capillary tube with a micrometric scale diameter was employed as a micro-stylus. To obtain a low measuring force, the local attractive interaction force on the surface of the workpieces was detected by the vibrating micro-stylus and used as the probing trigger signal. The vibration in the main axis direction of the stylus allowed detection of the local surface interaction force in all directions around the stylus shaft. In this paper, the principle and configuration of the developed microprobe are mentioned. Probing detections around the stylus shaft were verified by the surface detection of a pin gauge. Repeatability of the probing by the developed microprobing system was evaluated.
Sliding mechanical parts working under heavy loads and at high speeds in harsh environments are often subjected to sand and dust, leading to abnormal wear and seizing. Although sliding surfaces can be hardened and textured, there is a need for even higher wear and seizure resistance. We therefore did this study to confirm the trapping effect of surface texturing on dust by finding a way to visualize the dust. As a result, we confirmed that the dust became trapped in the grooves of the texture during the sliding. In addition, to produce a sliding surface having both seizure and wear resistance, we produced a surface combining a diamond-like carbon (DLC) film and surface texturing, and we evaluated its tribological characteristics. In dusty conditions, the specific wear rate was about 1/20 on surfaces where DLC film and the surface texturing were used in conjunction, and its wear resistance was higher than that of a non-treated stainless steel substrate. On the other hand, a rise in the coefficient of friction due to a rise in contact stress on the corners of the texturing grooves was confirmed. Therefore, when the tribological characteristics were evaluated by changing the radii of the groove corners and the parameters of the groove depth, the coefficient of friction was the lowest, decreasing about 50% for the test sample with a corner radius of 7.1 μm.
Deterministic lateral displacement (DLD) based microfluidic devices have been developed for capturing circulating tumor cells (CTCs) from the peripheral blood. There was frequent and problematic channel clogging around the micro-post array formed on a microchannel of the device. In this study, various agents were dispersed into the blood specimen to avoid clogging. At first, platelet aggregation was considered to be the cause of the clogging, but even plasmin, which was assumed to decompose platelet aggregations, did not show obvious inhibition of the clogging. Then, enzymes used for cell detachment from tissue were examined and decomposition of the clogging residue was observed. Finally, dispersion of deoxyribonuclease into a blood specimen was found to be effective for the inhibition of clogging. The existence of DNA in the clogging residue was also confirmed by propidium iodide (PI) staining, suggesting DNA adhering to the micro-post.
This paper proposes a mechanism for preventing needle buckling and skin deformation by mimicking the mosquito’s labium and discusses a puncturing device with a jig-integrated microneedle, based on the proposed mechanism. A sheet simplifying this mechanism was attached to an artificial skin’s surface, and experiments to puncture this artificial skin and corresponding finite element method (FEM) analysis were conducted. It was confirmed that the deformation of the puncture target and the puncture resistance force decreased with the use of the sheet. Based on these experimental and FEM-analytical results, a puncturing device with a jig-integrated needle has been designed and fabricated with 3D laser lithography. Experiments have been conducted with the fabricated device to puncture an artificial skin and the skin of a nude mouse to determine needle buckling prevention and the reduction in skin deformation. The study successfully samples blood from the mouse without stagnation of blood flow.
A multiple-degree-of-freedom (multi-DOF) motor can constitute small-sized and lightweight systems capable of performing complicated motions. Furthermore, the prospects for applications to industrial instruments via a direct drive are promising. This study aimed to develop practical multi-DOF motors capable of performing high-power rotary and linear motions using conventional three-phase inverters. A motor that performs rotary and linear motions is proposed. First, a method is presented for installing a salient pole on a needle with magnets. The method facilitates the use of soft magnetic materials with low eddy-current loss as iron cores. This study demonstrated the effectiveness of the salient pole for increasing the electromagnetic force. The model is used to explain the interactive magnetic interference generated by the armature currents for rotational and translation motions.