In semiconductor equipment and medical equipment industries, there is a requirement for a technique to accurately and efficiently process fine holes <1 mm in diameter in brittle materials, such as glass. Generally, hard and brittle materials, such as glass, are difficult to cut. However, there are many requirements for practical applications by cutting. To respond to these demands, an ultrasound-assisted method was applied to drill 0.3-mm holes, and the tool behavior and cutting resistance immediately after tool contact were evaluated. The results indicated that the spiral-shaped cutting force disappeared at contact with the drill when using ultrasonic drilling, and the hole positioning accuracy was improved compared to conventional drilling.

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Previously, we developed a modified melt blowing method for stable mass production of non-woven polypropylene nanofiber fabric. Here, we focus on an abrasive buffing application with machining center. We produced a buffing tool with non-woven nanofiber fabric, and investigated its buffing mechanism. The results indicated that the combination of fiber diameter, bulk density, and grain diameter markedly influence the buffing machining characteristics.

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The effects of the grinding conditions on machining performance in the process of Si wafer rotary grinding are generally evaluated using the ratio between the rotational speeds of the grinding wheel and the wafer. Here, we propose that it is not appropriate to evaluate machining performance using this rotation speed ratio, because the grinding length, L, between the grinding wheel and the wafer changes according to the diameter. Furthermore, the level of damage to the wafer surface varies with the grinding wheel feed rate, which dictates grain depth of cut, D. Therefore, we defined a new dimensionless number, the grain approach angle, D/L. Si wafer grinding was then performed to investigate the effects of surface roughness and power consumption of the grinding wheel spindle on the grain approach angle. It was surmised that ductile mode grinding occurred under grinding conditions with D/L≤3×10^-10.

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