Koike, Ryo

写真a

Affiliation

Faculty of Science and Technology, Department of System Design Engineering (Yagami)

Position

Associate Professor
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Career 【 Display / hide 】

  • 2016.04
    -
    2019.03

    Keio University, Faculty of Science and Engineering, Department of System Design Engineering, Research Associate (Temporary)

  • 2019.04
    -
    2024.03

    Keio University, Faculty of Science and Engineering, Department of System Design Engineering, Senior Assistant Professor

  • 2024.04
    -
    Present

    Keio University, Faculty of Science and Engineering, Department of System Design Engineering, Associate Professor

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Academic Background 【 Display / hide 】

  • 2008.04
    -
    2012.03

    Keio University, Faculty of Science and Engineering, Department of System Design Engineering

    University, Graduated

  • 2012.04
    -
    2013.09

    Keio University, The Graduate School of Science and Technology, Integrated Design Engineering

    Graduate School, Completed, Master's course

  • 2013.09
    -
    2016.03

    Keio University, The Graduate School of Science and Technology, Integrated Design Engineering

    Graduate School, Completed, Doctoral course

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Papers 【 Display / hide 】

  • In-situ heat treatment via preheating and liquid cooling during high-speed coating of gears by directed energy deposition

    Yokota M., Takemura S., Koike R., Maki T., Takaki K., Mori T., Hirono Y., Kakinuma Y.

    CIRP Journal of Manufacturing Science and Technology 61   114 - 127 2025.10

    ISSN  17555817

    　View Summary

    Automobile electrification has increased demand for higher-performance gears in drivetrains with specialized functional requirements beyond what conventional carburizing heat treatment can deliver. While carburizing is effective for mass production, it faces inherent limitations in achieving advanced material properties needed for next-generation applications. Therefore, this study proposes a high-speed coating method on rotational gear surfaces using directed energy deposition (DED). The proposed method can form the coating layer continuously and efficiently on the complex-shaped teeth of the gear, compared to the common method that forms coating along a complicated path matching the part's geometry. Furthermore, a localized heat treatment system integrating laser preheating and liquid cooling is introduced to precisely control material characteristics of the coating layer. Experimental results demonstrate that this combined heat treatment achieves a crack-free, hard coating layer on preformed gears. This method shows significant potential for producing customized, high-performance gears for specialized applications in next-generation vehicles while reducing process complexity.

  • Digital Twin in Process Planning of the Additive and Subtractive Process Chain for Laser Metal Deposition and Micro Milling of Stainless Steel

    Denkena B., Wichmann M., Malek T., Nguyen H.N., Kato M., Isshiki K., Koike R., Kakinuma Y.

    Journal of Manufacturing Science and Engineering 146 ( 7 )  2024.07

    ISSN  10871357

    　View Summary

    Additive and subtractive (Add/Sub) manufacturing processes are increasingly being combined to produce complex parts with unique geometries and properties. However, the design of such combined processes is often challenging as it requires a deep understanding of the interaction between the different processes. On the other hand, digital twin (DT) technology has become a powerful tool in recent years for optimizing manufacturing processes. This article explores the use of the digital twin technology for a holistic process planning of combined additive and subtractive processes. The article describes the integration of laser metal deposition (LMD) and micro-milling prediction models of resulting geometry (width and height), hardness, and surface roughness into the digital twin. This is then used for combined process planning to achieve different target values regarding resulting geometry and surface roughness. For the planning of this combined process chain, further criteria such as tool life, energy, and process time are considered in the optimization, showing the potential for sustainable and efficient production. Sensorless cutting force estimation is also used to detect small cutting forces, with the potential to use this as a soft sensor for roughness estimation. The measured width, height, and roughness as a result of the process parameters suggested by the optimization algorithms showed a mean absolute percentage error (MAPE) of 4, 17, and 16%, respectively.

  • Effects of high gravity on properties of parts fabricated using material extrusion system by additive manufacturing

    Jiang X., Koike R.

    Heliyon 10 ( 11 )  2024.06

    ISSN  24058440

    　View Summary

    Additive manufacturing (AM) has gained significant attention in recent years owing to its ability to fabricate intricate shapes and structures that are often challenging or unattainable using conventional manufacturing techniques. This high-quality development trend entails higher requirements for the structural design of 3D printers. In this study, polylactic acid (PLA) and acrylonitrile butadiene styrene (ABS) filaments were fed through a heated extrusion nozzle, which melted the material and deposited it onto a build platform. This study's objectives are high-gravitational material extrusion (HG-MEX) systems development, analyzing the high gravity influences on the flow behavior of materials during extrusion, and understanding the effects of gravitational on material flow and overall extrusion performance. HG-MEX systems have great potential for addressing various challenges in additive manufacturing, such as precise manufacturing. The highlight of the progress is that we developed an HG-MEX system and applied surface science to material extrusion in different gravity. We established a system and obtained results on different gravity, we analyzed the analogy between different gravity phenomena. We analyzed the interplay between the behavior of the fabricated parts and gravity. We analyzed high gravity effects on extrusion processes. The results confirmed the characteristics and feasibility of the developed system. The results suggest that a material extrusion line operating under 15 G conditions resulted in better printing quality compared to one operating under 1 G conditions. This observation implies that high gravity had a positive effect on the extrusion process, leading to improved material extrusion performance.

  • Influence of metal structure on mechanical characteristics in high-speed coating layer fabricated via Directed Energy Deposition

    Hashimoto M., Koike R., Kakinuma Y., Hirono Y., Mori T., Oda Y.

    Procedia CIRP 124   227 - 230 2024

    ISSN  22128271

    　View Summary

    Directed energy deposition (DED) is an additive manufacturing process wherein a metal powder is fed through a nozzle onto a baseplate, melted, and solidified using a laser. Potential applications of DED have been actively discussed. In this study, laser-based DED (DED-LB) was applied as a high-speed metal-coating technique to a cylindrical pipe. The mechanical properties of DED-fabricated objects were strongly affected by processing parameters such as laser power, powder feed rate, and rotational speed of the cylindrical pipe when using 20MnCr5 and M2 as the coating materials. Hardness measurements showed that the hardness of 20MnCr5 increased with a high heat input, whereas that of M2 increased with a low heat input. The two metals exhibited opposite trends in terms of hardness variation because of the differences in their transformation points. This study analyzed a layer coated with DED-LB from the viewpoint of metal morphology.

  • Metal Additive Manufacturing Improved in High Gravitational Fields

    Koike R.

    Yosetsu Gakkai Shi Journal of the Japan Welding Society 93 ( 7 ) 429 - 434 2024

    ISSN  00214787

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Papers, etc., Registered in KOARA 【 Display / hide 】

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Research Projects of Competitive Funds, etc. 【 Display / hide 】

  • Low-density foam metal fabrication based on net-zero gravity process

    2022.04
    -
    2025.03

    MEXT,JSPS, Grant-in-Aid for Scientific Research, 基盤研究(B), Principal investigator

  • Metal 3D printing by powder bed fusion applying artificial gravity control

    2019.04
    -
    2022.03

    MEXT,JSPS, Grant-in-Aid for Scientific Research, Grant-in-Aid for Early-Career Scientists , Principal investigator

  • Development of direct deposition for porous structure based on molten-metal dynamics analysis with particle method

    2017.04
    -
    2019.03

    MEXT,JSPS, Grant-in-Aid for Scientific Research, Grant-in-Aid for Young Scientists (B), Principal investigator

  • 合金固液相変化を解析する指向性エネルギー堆積法シミュレータの開発

    2016.08
    -
    2018.03

    MEXT,JSPS, Grant-in-Aid for Scientific Research, Grant-in-Aid for Research Activity Start-up , Principal investigator

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Courses Taught 【 Display / hide 】

  • SEMINAR IN SYSTEM DESIGN ENGINEERING

    2025

  • MACHINE DESIGN

    2025

  • LABORATORIES IN SYSTEM DESIGN ENGINEERING 2)

    2025

  • LABORATORIES IN SYSTEM DESIGN ENGINEERING 1)

    2025

  • INTRODUCTION TO SYSTEM DESIGN ENGINEERING

    2025

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