2018 Fiscal Year Final Research Report
Micro-bubble assisted abrasive waterjet polishing
| Project/Area Number |
17K14571
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| Research Category |
Grant-in-Aid for Young Scientists (B)
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| Allocation Type | Multi-year Fund |
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| Research Field |
Production engineering/Processing studies
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| Research Institution | Kyoto University |
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Principal Investigator |
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| Project Period (FY) |
2017-04-01 – 2019-03-31
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| Keywords | ultra-precision / fluid jet polishing / ultrasonic cavitation / material removal / surface finishing / optical surfaces / medical surfaces |
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| Outline of Final Research Achievements |
In fluid jet polishing (FJP), a polishing liquid is pressurized as a jet and and impinges a surface. An improved system consisting of an ultrasonic transducer and acoustic lens mounted atop the FJP nozzle cavity was tested, which boosted material removal rates by up-to 1000%. However, it was not clear whether the removal boost was due to a micro-scale or macro-scale phenomenon.
A study of micro-pit formation by collapsing micro-bubbles in the near wall region determined that micro-jetting and water hammer pressure do not seem to occur in UFJP, so the micro-scale hypothesis was ruled out.
A study of workpiece vibrations found that significant shear forces exist at the workpiece surface when ultrasonic vibration is applied to the FJP beam. After theoretical confirmation of the correlation between macro-scale fluid displacement and shear force, the standard erosion model in FJP was modified by adding time-averaged vibration terms. The model and experiments were finally in good agreement.
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| Free Research Field |
マイクロエンジニアリング（工学）
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| Academic Significance and Societal Importance of the Research Achievements |
Fluid jet polishing is a very flexible method for polishing small and complex surfaces, such as aspheric lenses for smartphones or dental implants, but was however inefficient. With this research, the productivity of FJP was greatly enhanced, which will benefit consummers of such important products.
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