This study analyzed acoustic emission (AE) signals generated during ultrasonic machining of SiC cathodes and evaluated classification performances of various machine learning models. AE data were collected in both waveform and hit formats, enabling signal characterization through statistical analysis and frequency domain examination. Various machine learning models, including XGBoost, KNN, Logistic Regression, SVM, and MLP, were applied to classify machining states. Results showed that XGBoost achieved the highest classification accuracy across all sensor positions, particularly at the upper part of the worktable with an accuracy of 98.35%. Additional experiments confirmed the consistency of these findings, highlighting the influence of sensor placement on classification performance. This study demonstrates the feasibility of monitoring AE-based machining state using machine learning and emphasizes the importance of sensor placement and signal analysis in improving classification accuracy. Future research should incorporate defect data and deep learning approaches to further enhance classification performance and process monitoring capabilities.
A lamb wave propagation behavior on a freestanding nanoscale membrane was investigated using a laser ultrasonic technique in the present study. A 110-nm thick aluminum (Al) layer was deposited on a rectangular 200-nm thick silicon nitride (SiN) membrane and the Lamb wave was launched using a pulsed laser. The transfer matrix technique was employed to obtain a theoretical dispersion curve so that material properties of the SiN membrane could be estimated through curve-fitting. In addition, picosecond ultrasonic measurement was used to characterize the Al film. Results showed that the dispersive behavior of Lamb wave in the fundamental antisymmetric mode could be clearly observed on the membrane. However, comparison of dispersion curves indicated that the effect of residual stress of the film became more influential at a low dimensional scale.
Chronic wounds necessitate periodic treatment and management due to their potential for serious complications. Recently, ultrasonic mist therapy has been introduced to treat chronic wounds efficiently. This therapy requires a noncontact spraying method to prevent side effects such as bacterial infections and pain. Therefore, research is needed on a spray nozzle tip that can effectively transmit ultrasonic energy to the wound target with misted cleaning solution mobility in a specific direction and at an appropriate speed. The performance of the nozzle tip is greatly affected by the flow characteristics inside it. Computational fluid dynamics (CFD) is a powerful tool to analyze these characteristics in detail. The behavior of the mist was analyzed in a simulation based on discrete phase model methodology in an unsteady state. Valid design parameters enabling noncontact cleaning were determined by setting the design parameters of the nozzle tip`s internal flow path and measuring the spraying speed of the mist using CFD analysis. Through the simulation results, information on the sprayed skin surface and spray characteristics are measured. Lastly, we present a nozzle tip design guide optimized for ultrasonic mist therapy.
A hybrid cladding technology was developed by combining direct energy deposition (DED) and ultrasonic nanocrystal surface modification (UNSM). This is an effective process to control the mechanical properties inside the metal-clad layer, but the scope to improve the internal properties is low. Therefore, in this study, the UNSM process was applied while heating at 300 and 600℃ to increase the effectiveness of this hybrid additive process. To validate the characteristics of this method, a study on the cross-sectional properties upon application of heating was conducted. Hybrid cladding at 300 degrees produced improvements- over a 40% larger area than the results at room temperature. At 600 degrees, the hybrid cladding improved mechanical properties over a larger area by nearly 2 times. In this study, the characteristics of the roomtemperature and the high-temperature hybrid cladding process were analyzed. The proposed method shows a high improvement effect and is a promising method to improve the internal mechanical properties of the cladded layer.
This study aimed to determine effects of ultrasonic nanocrystal surface modification (UNSM) as a surface pre-process on performance and surface characteristics of bolts manufactured through a screw rolling process. Surface roughness, hardness, and microstructural changes after UNSM treatment were examined. Results showed no significant defects such as cracks in all fabricated samples after screw rolling of bolt pre-processed by UNSM treatment. In addition, material flow was continuously maintained without disconnection. After UNSM treatment, surface roughness was improved for both body and screw parts. The surface roughness of the UNSM treated screw part was improved the most at 43%. Hardness test showed the greatest increase in hardness on the surface hit by the UNSM ball tip, with hardness improved to about 500 μm deep from the surface. The hardness at the screw part was the highest at 471 HV, which was attributed to the fact that grains near the surface were deformed and refined by UNSM treatment followed by screw rolling. Near the surface of the screw, refined grains and high dislocation density were clearly observed by EBSD mapping. These results confirm that UNSM treatment before screw rolling is effective in improving mechanical properties of screw rolled bolts.
Most of the consumables used in the CMP (Chemical Mechanical Planarization) process are discarded because it is difficult to reuse them. Slurry accounts for most of the consumables, so research is being conducted to reduce the amount of slurry used. A previous study explains that when the same amount of slurry is injected, the material removal rate is improved when the slurry is injected wide and thin instead of the tube nozzle, which is the conventional slurry injection method. However, there was no change in the injection method due to the problems of the injection method suggested in previous studies and the lack of follow-up studies. Thus, in this paper, an injection method through an ultrasonic spray nozzle is proposed to improve the problems of the injection method proposed in previous studies. Additionally, it is intended to calculate the slurry film thickness according to the spraying range and to explain the effect of the film thickness on the material removal rate.
Until recently, solar energy has been considered as a promising regeneration energy source in the future. Solar cell wafer production involves ingot cutting, cleaning, and packaging processes. In this research, design, fabrication, and testing of a batch-type midsonic for cleaning solar cell wafers were carried out. To reduce the damage compared to conventional systems, we decided to use 400 kHz in a midsonic wave range, and we used far-field to obtain a more regular acoustic pressure. Finite element analysis with Ansys software predicted an anti-resonance frequency of 458 kHz for an ultrasonic waveguide, and the measured result of the fabricated system was 454 kHz with a 0.9% error. Acoustic pressures were measured, and the result confirmed regular and high distributions. Finally, cleaning tests were performed, and a 90% particle removal efficiency (PRE) was achieved at 900 W. Thus, the newly developed midsonic cleaning system can be considered to clean particles on solar cell wafers efficiently while preventing damage.
The ultrasonic metal welding technique has been widely used because of the need to weld different materials for meeting high quality performance requirements. The key part in this type of welding is the horn, which plays an important role in the weld quality. Longitudinal vibration has so far been the most popular vibration mode for ultrasonic horns, but the longitudinal mode coupled with torsional mode is gaining a lot of attention these days owing to its better performance compared to the pure longitudinal mode. Although there are many studies on the performance of these two mode horns, comparative studies based on the performance of these two modes, particularly in ultrasonic metal welding, are very rare. This study focuses on the welding performance comparison of these two horns with 20 kHz resonant frequency. Experimental results show that the performance of the longitudinal-torsional horn is better than that of the longitudinal horn in terms of welding strength.
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Trade-off between dynamic recrystallization and material ejection during ultrasonic welding of cylindrical cell current collector plate and positive terminal Mounarik Mondal, Savyasachi Nellikode, Seong-Beom Park, Jun Mitsuyuki, Soomin Lee, Do-Hyeong Kim, Yeong-Do Park The International Journal of Advanced Manufacturing Technology.2025; 137(11-12): 5837. CrossRef
The application of ultrasound in Joining: Principles, processes and properties Zongkai Fan, Keran Bai, Chao Chen Journal of Manufacturing Processes.2023; 101: 269. CrossRef
Ultrasonic cutting is used not only for cutting various materials such as metals and non-metals, but also for bone cutting of the human body or for various surgical operations. In recent, ultrasonic cutting technology is being applied for cutting various food products such as cakes, pizza, and cheese. It is shown that ultrasonic vibrations for cutting food products enables high-precision and high-quality cutting, and the quality of the cutting surface is affected by the shape of food products and cutting conditions. However, most of the studies have been on industrial cutting horns that can be used in large-scale grocery factories, but these cutting horns are very different from the shape of knives used in the households. Accordingly, research or technology development for ultrasonic cutting knives that can be used in household has not been studied. Therefore, this study developed a knife that can cut or process food by applying ultrasonic vibration while having a shape similar to the existing knife as possible so that it can be used in general. To develop such a knife, a modal analysis was performed using the finite element method for knife models of various shapes, and a suitable model for a kitchen knife was proposed.
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Recently, interest in astronomy has increased internationally, and the technological development of lenses for large space telescopes is progressing. The multi-order diffractive engineered (MODE) lenses can make a large space telescope light and thin. However, because glass lenses are difficult to machine, we have adopted a method of molding at high temperature and high pressure. The STAVAX is commercially available chrome alloy stainless steel, and it is applied as various mold materials. The ultrasonic vibration cutting was adopted for ultra-precision machining because the tool wear is severe when cutting the STAVAX with a diamond tool. To achieve a flat surface for smooth ultrasonic vibration cutting, we performed a precise shape cutting using a CBN tool and confirmed and observed changes in the surface roughness and hardness depending on the cutting conditions. The ultrasonic vibration cutting was performed on the surface of the machine using a CBN tool, and the surface roughness was observed. It was confirmed that the surface roughness was impacted by the surface hardness. The specimens with low surface hardness showed the highest surface roughness at approximately 3 nm.
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Various chemicals are used for semiconductor process. In particular, the most important element in the etching and cleaning process is chemical liquid. An ultrasonic flow meter is used to monitor the supplying amount of chemical solution. If the ultrasonic flow meter contains bubble inside the liquid, measurement cannot be performed or measurement error will be occurred. In this research, the waveform was improved by zero-crossing processing so that the influence on measurement performance is negligible even if the bubble in the chemical solution is included. Consequently, the amplitude of the sound wave is attenuated. Existing flow meters monitor the amplitude value to determine the authenticity of the signal and to filter the noise. The improved method in this study distinguishes noise waves and monitors signal frequency. Flow measurement was carrying out even when the amplitude was resulting only less than 3% of input level volt. The system developed of this study has shown an exact measuring performance compared with the other make’s flow meters.
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Picosecond ultrasonic evaluation on the Young’s modulus of a ceramic thin-film was performed in the present study. A 100nm thick silicon nitride thin-film was deposited on a silicon wafer using the plasma enhanced chemical vapor deposition technique and gigahertz-frequency longitudinal bulk waves were excited in the film using a femtosecond laser setup. A thermoelastic equation was numerically solved using the finite difference method and compared to the experimental data to estimate the elastic property of the film. Results show that the present measurement technique can effectively evaluate the film’s Young’s modulus and it is recognized that the modulus is 60-70% lower than that of its bulk status. This study is expected to provide a way to characterize nanoscale ceramics with very high spatial and temporal resolutions for the design and analysis of microelectromechanical systems and thin-film based devices.
Defects in the insulator bushing are the major caution of destroying a switchgear. An epoxy bushing is composed of epoxy-molded insulator layer and a conductor. That means, a porosity or delamination defect could be included in the insulating layer by the manufacturing process. An inspection method is required to secure integrity of the bushing. An ultrasonic-immersion system has the power to produce a required effect to examine critically an epoxy material with high degree of fineness. In this research, an optimized ultrasonic immersion system was developed and applied to examine critically the epoxy-layer of bushings. As results of the result of a careful examination, both artificial defects and delamination were detected by the system. Currently, the ultrasonic-immersion system should be applied for examining the epoxy-layer of the bushing carefully.
Finite element analyses were carried out to investigate the effect of ultrasonic vibration on drawing force in large diameter tube drawing. Ultrasonic vibration was imposed to a drawing die using ultrasonic vibration horns. The horn was designed to have desired amplification ratio and natural frequency using a wave equation. The drawing forces obtained with and without ultrasonic vibration were compared. The effect of vibration amplitude and phase delay of two horns located in opposite side on drawing force was investigated. Results showed that the drawing force could be reduced about 11% by using ultrasonic vibration of 20 μm amplitude and that the phase shift of two opposite horns had a great effect on the drawing force.
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