Papers by Author: Toshiyuki Enomoto

Abstract: Nickel-based superalloys such as Inconel 718 are known as one of the most difficult-to-cut materials due to their mechanical and chemical properties and the tool life is extremely short. Recently, Cubic-Boron-Nitride (CBN) has received a considerable attention as a material for cutting tools and has been considered to be a major candidate for high performance cutting of Inconel 718. However, the detailed wear behavior of CBN tools in cutting of Inconel 718 is not sufficiently understood yet, and the performances of CBN tools are still insufficient in practical use. To overcome this problem, we first conducted orthogonal cutting experiments on Inconel 718 at low (20 m/min) and high (100 m/min) cutting speeds employing CBN cutting tools to clarify the detailed wear mechanisms. Moreover, relationship between surface microstructures of the cutting tool and wear resistance was investigated. As a result, it was found that a rake face with micro grooves significantly suppressed the crater wear at low cutting speed, although polished surface rake face reduced the initial crater wear by approximately 40 % compared to the non-polished tool in high speed cutting of Inconel 718.

Abstract: In cutting of aluminum alloys, one of the most serious problems is chip adhesion to cutting tool surface, often leading to tool failure, above all, in dry cutting. To address this problem, we adopted surface engineering approach, namely, a functionalization of tool surfaces by textures. In our previous research, we have developed the DLC-coated cutting tool with nano/micro-textured surfaces and the cutting tool with micro stripe textured surface formed using femtosecond laser technology. Face-milling experiments on aluminum alloys showed that the nano/micro-textured surface suppresses the genesis of adhesion at the atomic level. On the other hand, it was found that micro stripe texture prevents chip adhesion from growing larger even in dry cutting conditions. In this study, a cutting tool with new textured surface combined nano/micro texture and micro stripe texture was developed in order to further improve anti-adhesiveness in cutting of aluminum alloys. As a result, it was confirmed that the combined texture brings excellent anti-adhesion compared to the previously developed tools.

Abstract: Demand for diminishing edge roll off of workpiece has rapidly increased, especially in polishing silicon wafers and glass disks. However, the conventional polishing technologies cannot meet the demand. To address this problem, the influence of carrier film properties and that of polishing pad properties on the stress distribution near the workpiece edge were investigated using finite element methods. Based on the analytical results, double-layered polishing pads having an extra-fine fiber thin layer and a hard polymer layer were developed. Polishing experiments on silicon wafers and glass plates showed that the developed polishing pads achieved high finishing efficiency and extremely flat surface near the edge.

Abstract: In recent years, the achievement of further high flatness of workpiece edge shape is strongly required in mirror finishing. Especially, the edge roll off of silicon wafers as the substrates of semiconductor devices is demanded to decrease in the polishing process for raising the yield of IC chips. Many theoretical and experimental analyses for the edge roll off generation have been already done to meet the demand. The analyses, however, cannot fully account for the obtained edge shape in actual polishing. Concretely, the influence of the polishing pressure as one of the key polishing conditions on the edge roll off has not been clarified. In this study, the influence of the polishing pressure on the edge shape was investigated by the polishing experiments and the edge roll off generation analyses using the model based on the viscoelasticity of the polishing pad, which was proposed in the previous study. And it was revealed that an appropriate polishing pressure is needed to be set for achieving high flatness of workpiece edge shape with the consideration of the properties of applied polishing pads.