Faculty Profiles - OKADA Akira

Papers - OKADA Akira

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Reconditioning of Diamond Coated Tools and Its Impact on Cutting Performance for CFRP Laminates Reviewed International coauthorship International journal

Alexander Soldatov, Alexey Remnev, Akira Okada

Applied Sciences 12 ( 3 ) 1288 - 1288 2022.1

Authorship：Last author,　Corresponding author Language：English Publishing type：Research paper (scientific journal) Publisher：MDPI AG

In recent years, CVD diamond-coated tungsten carbide (WC-Co) tools have been widely utilized due to their benefits in the machining of non-ferrous alloys and polymer composite materials, especially carbon-fiber-reinforced plastics (CFRPs). The reconditioning of such coated tools is economically attractive due to their high cost and short tool life. The decoating of the remaining diamond film from the used tools and the subsequent surface preparation by wet chemical pretreatment are essential steps for new CVD diamond film formation. Previously, it was shown that reactive ion beam etching (RIBE) could effectively remove CVD diamond films. However, some degree of WC-Co tool substrate damage is expected due to the high ion energy in RIBE and the chemical activity in wet etching. This study addresses the effects of RIBE decoating and surface pretreatment steps on WC-Co tools with a complex shape in terms of the ion-induced surface damage, geometry alteration, and adhesion of a subsequently re-applied CVD diamond film. Moreover, the cutting performance of the tools subjected to the RIBE decoating and repeated film deposition was studied via CFRP cutting tests. It has been shown that the RIBE decoated and recoated tools had a high level of cutting performance comparable to the new tools.

DOI： 10.3390/app12031288

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Bottom surface smoothing of high aspect ratio hole by guiding large-area electron beam with magnet Reviewed International journal

Togo Shinonaga, Jiayu Lu, Mitsuhiro Kimura, Motohiro Inoue, Akira Okada

The International Journal of Advanced Manufacturing Technology 119 4979 - 4990 2022.1

Authorship：Last author,　Corresponding author Language：English Publishing type：Research paper (scientific journal) Publisher：Springer Science and Business Media LLC

DOI： 10.1007/s00170-021-08380-w

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Other Link： https://link.springer.com/article/10.1007/s00170-021-08380-w/fulltext.html

Development of Curved Hole Drilling Method by EDM with Suspended Ball Electrode Reviewed

Atsushi YAMAGUCHI, Yuta INABA, Sho SHIRAGA, Akira OKADA

Journal of the Japan Society for Precision Engineering 87 ( 5 ) 461 - 466 2021.5

Fundamental study on reduction of dross in fiber laser cutting of steel by shifting nozzle axis Reviewed International journal

Atsushi Yagi, Seigo Kadonaga, Yasuhiro Okamoto, Hiroaki Ishiguro, Ryohei Ito, Akihiko Sugiyama, Hiroshi Okawa, Rio Fujita, Akira Okada

Journal of Laser Applications 33 ( 1 ) 012022 - 012022 2021.2

Surface smoothing and repairing of additively manufactured metal products by large-area electron beam irradiation Reviewed International journal

T. Shinonaga, A. Yamaguchi, Y. Okamoto, A. Okada

CIRP Annals - Manufacturing Technology 70 ( 1 ) 143 - 146 2021

High-quality Welding of Copper and Aluminum by Angled Laser Irradiation and Insert Metals Reviewed

Yasuhiro Okamoto, Yuki Yamada, Akira Okada, Masaki Miyake, Takeshi Yamamura, Katsutoshi Nagasaki, Norio Nishi

Proceedings of 43rd International Congress on Applications of Lasers & Electro-Optics 2024 2024.11

Fundamental study on dielectric oil viscosity for high-performance wire EDM Reviewed International journal

Shixian Liu, Akira Okada, Tomohiko Kitamura

The International Journal of Advanced Manufacturing Technology 135 ( 7-8 ) 3451 - 3461 2024.10

Authorship：Corresponding author Language：English Publishing type：Research paper (scientific journal) Publisher：Springer Science and Business Media LLC

Abstract

Dielectric oil has been recently used in wire electrical discharge machining (wire EDM) for achieving high-precision machining. However, the influence of dielectric oil properties on wire EDM characteristics has not been clarified sufficiently. This study fundamentally investigated the influence of dielectric oil viscosity on wire EDM characteristics. In this study, three types of dielectric oil differing only in viscosity were prepared and examined. Linear cutting experiment results showed that the removal rate and the machined surface roughness increase with dielectric oil viscosity. Then, the influence of viscosity on crater removal volume was investigated to discuss the cause of the change in removal rate, and it was found that crater removal volume increases with the viscosity. Furthermore, CFD (computational fluid dynamics) analysis results and discharge observation results showed that the debris exclusion becomes worse in higher viscosity oil, and the discharge concentration occurs frequently, resulting in the deterioration in machined surface roughness. Next, the difference in machining accuracy with dielectric oil viscosity was investigated. It was found that the corner shape accuracy deteriorates with the increase of viscosity while the machined surface waviness and straightness improve slightly. Structural analysis results showed that wire deflection increases with viscosity, resulting in the deterioration in corner shape accuracy. On the other hand, high-speed observation of wire vibration was carried out, and it was found that the wire vibration decreases in the case of higher viscosity, which leads to the improvement in machined surface waviness and straightness.

DOI： 10.1007/s00170-024-14693-3

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Other Link： https://link.springer.com/article/10.1007/s00170-024-14693-3/fulltext.html

Fundamental Study on Calcination of Limestone Particles by Near-infrared Wavelength Laser with Vibration Stirring Reviewed

Naoki Kotake, Yasuhiro Okamoto, Masakazu Oka, Shuji Fujiki, Shunjiro, Shizuka, Akira Okada

Proceedings of ICPE2024 Os10-11 2024.10

Influence of Dielectric Oil Cooling-effect on Wire EDM Characteristics Reviewed International journal

Shixian Liu, Ren Sakata, Tomohiko Kitamura, Akira Okada

Proceedings of The 5th International Conference on Machining, Materials and Mechanical Technologies (IC3MT2024) 2024.10

Effect of Chromium Carbide Coating on Mold Releasability from Ground Surface in Compression Molding of Thermosetting Phenol Resin Reviewed

Ryoji Kitada, C. Sun, Q. Wang, K. Yoshida, A. Okada

Proceedings of The 20th International Conference on Precision Engineering 2024.10

Highly Efficient Surface Smoothing of AMed Metal Products by Long-pulse Electron Beam Irradiation Reviewed International journal

Xuze Zhao, Togo Shinonaga, Akira Okada

Proceedings of The 20th International Conference on Precision Engineering 2024.10

Study on Surface Smoothing of Metal Lattice Structures by Large area Electron Beam Irradiation Method Reviewed International journal

Seiya Miura, Togo Shinonaga, Atsushi Yamaguchi, Akira Okada

Proceedings of The 20th International Conference on Precision Engineering 2024.10

Bent and Curved Hole EDM Drilling Using Suspended Ball Electrode with Guides Reviewed

Atsushi YAMAGUCHI, Akira OKADA

Journal of the Japan Society for Precision Engineering 90 ( 9 ) 696 - 700 2024.9

High-speed Observation of Bubble Exclusion Behavior in Fine Wire EDM Reviewed International journal

Shun Ishibashi, Hidetaka Okamoto, Akira Okada

Proceedings of The 5th International Conference on Machining, Materials and Mechanical Technologies (IC3MT2024) 2024.9

Fundamental Study on Wire EDM Characteristics of Copper Diamond Composite Reviewed International journal

Koki Yoshida, a, Jiadong Sun, Akira Okada

Proceedings of The 5th International Conference on Machining, Materials and Mechanical Technologies (IC3MT2024) 2024.9

Effect of Cooling Rate Control on Surface Modified Layer of Al-Cu Alloy by Large-area EB Irraadiation Reviewed International journal

Ayano Sebe, Togo Shinonaga, Akira Okada

Proceedings of Proceedings of The 5th International Conference on Machining, Materials and Mechanical Technologies (IC3MT2024) 2024.9

Study on Surface Topography and Properties of Additively Manufactured Martensitic Stainless Steel Products Reviewed International journal

Yuki Matsuda, Togo Shinonaga, Atsushi Yamaguchi, Akira Okada

Proceedings of Proceedings of The 5th International Conference on Machining, Materials and Mechanical Technologies (IC3MT2024) 2024.9

Fundamental Study on Influence of Residual Stress Distribution on Fatigue Strength in ns Pulsed Laser Peening for Welded High-Strength Steel Reviewed International journal

Shoma Okura, Hao Pan, Yasuhiro Okamoto, Akira Okada, Yoshihiro Sakino, Tomoharu Kato

Proceedings of The 5th International Conference on Machining, Material and Mechanical Technologies (IC3MT 2024) 5 - 11 2024.9

Influence of Material Structure in Cemented Carbide on Fine Wire EDM Characteristics Reviewed International journal

Yuto Kuroda, Yudai Yamagami, Akira Okada

Proceedings of The 5th International Conference on Machining, Materials and Mechanical Technologies (IC3MT2024) 2024.9

Micro-structuring Characteristics on Metal Surface by High-speed Scanning of Angled CW Laser Irradiation Reviewed

Taiki Kawai, Riku Saitou, Atsuhiko Sakai, Yasuhiro Okamoto, Togo Shinonaga, Akira Okada

Technical Digest of the 25th International Symposium on Laser Precision Microfabrication – LPM2024 2024.6

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