Severe diamond tool wear may be caused by a chemical reaction between SiO₂ in glass and diamond during ultraprecision cutting of silica glass, because silica glass is based on SiO₂. This study demonstrated that adopting fluoride glass, which has no SiO₂ constituent, as the workpiece reduced tool edge retreat to 1/22 of that of silica glass. This was because the fluoride glass contains no SiO₂, which reacts chemically with diamond and leads to severe tool wear. Ductile mode cutting of fluoride glass was realized for long cutting distance. As an application, an aspherical glass lens was produced by ultraprecision cutting. In addition, the tool wear, surface generation, and chip formation mechanisms were investigated.

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Large-aperture optical glass lenses exceeding 200 mm in diameter are manufactured by grinding to create the desired shape, and the surface is then finished by polishing to remove cracks and grinding traces. However, polishing causes deterioration of form accuracy because polishing depth is up to 10 μm. To reduce the time of the polishing process, it is necessary to develop a high-efficiency and high-precision grinding method and quantitatively evaluate the subsurface damage formed in grinding. This study was performed to investigate the optical glass grinding performance using a rubber-bonded wheel with excellent elasticity in place of the conventional resin-bonded wheel. Subsurface damage was evaluated and analyzed by hydrofluoric acid etching. The results indicated that the hardness of the grinding wheel and grinding mode influenced subsurface damage.

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In the processing of titanium alloys, it is necessary to reduce the depth of cut to suppress chatter vibration, and the material removal rate decreases. We developed a variable preload spindle that can improve the rigidity by changing the preload force, such that the cutting depth can be maintained without causing chatter vibration. Here, static stiffness test, impact vibration test and machining test were performed to evaluate the performance of the developed spindle. The results confirmed that static stiffness value was improved by 38% and compliance value in impact vibration test was reduced by approximately 50%, compared with the fixed-position preload spindle. In machining test, the vibration acceleration during machining was suppressed, and therefore the validity of the developed spindle was confirmed.

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