Emerging Technology in Precision Engineering XIV

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Authors: Hiroki Nakamori, Satoshi Matsuyama, Shota Imai, Takashi Kimura, Yasuhisa Sano, Yoshiki Kohmura, Kenji Tamasaku, Makina Yabashi, Tetsuya Ishikawa, Kazuto Yamauchi
Abstract: Ultraprecise piezoelectric deformable mirrors have been developed to construct adaptive X-ray focusing optics whose optical parameters can be varied while simultaneously performing wavefront correction. We designed and developed a deformable mirror that did not have high-spatial-frequency deformation errors. Using a Fizeau interferometer, we demonstrated that the mirror could be deformed with a peak-to-valley figure accuracy of 5 nm. In addition, wave-optical simulations based on the Fresnel–Kirchhoff integral revealed that the mirror could focus hard X-rays to 90 nm under diffraction-limited conditions.
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Authors: Kai Xu, Hiroyuki Sasahara
Abstract: This study describes a new machining strategy to make regularly aligned cutter marks on free-form surface efficiently for increasing the added value of industrial product. While the free-form surface is divided into many small patch segments employing curved surface patch division milling technique which can substitute for the conventional method, thus avoiding the influence of the change in the curvature. And the patch segments will be machined by a spiral tool path respectively, so that regularly aligned cutter marks can be successfully formed on the curved surface patches by controlling cross-feed, feed speed per tooth, number of teeth and the length of the tool path. Comparing the machined surface and the simulation result, the cutter marks agree with it. If the surface is machined only by the ball end milling with a machining center, this method will be a very effective tool for the machinery industry.
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Authors: Shigehiko Sakamoto, Hiroki Iwasa
Abstract: CFRP (Carbon Fiber Reinforced Plastics) has higher specific strength, modulus of elasticity and so on. In the application for aviation industries, CFRP are remarkably used for many parts of airplane structures. It will be also widely applied for automobile parts in the future. CFRP is, however, well known as difficult-to-cut material which has very strong physical and mechanical characteristics. Drilling technique of CFRP which is one of the most important cutting operations is currently carried out in industrial factories. These manufactured parts have containing many precision holes for various purposes such as rivet holes. There are many typical problems in the precision drilling processes of CFRP plates which are burrs, chippings and delamination of composite materials, rapid wear of drilling tools and so on In our researches, it is found that drilled holes on CFRP plate by ball-nose end mill have good quality without any defections. By using the helical method with cemented-carbide ball end mill, high quality holes on the CFRP plates are obtained without burrs, chippings, and so on. However, cutting heat have negative effect on the strength of CFRP when it transcend heatresistant temperature of epoxy resin. In these researches, it is considered that the effect of the revolution speed to cutting heat on helical cutting of CFRP plates to improve the cutting processes. It is found that the cutting heat become lower by increasing revolution speed. Besides, because of shortening the cutting time, it is restrained the heat from transferring to the workpiece.
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Authors: Yoshio Mizugaki, Kazuki Takafuji, Koichi Kikkawa, Teppei Kuroda, Taro Kimura
Abstract: This paper presents the experimental results of cutting performance and tool wear of a milling cutter in dry side milling of aluminum alloy A2017. The milling cutter consists of Co-bonded High-Speed-Steel matrix with Diamond-Like-Carbon coating (abbrev. DLC-coated HSS-Co cutter). The machining experiments were carried out under cutting speed of 63 to 189 [m•min-1] and feed of 0.08 [mm/tooth/rev], and the criterion of tool life was the generation of gauge and/or scratch on a machined surface. The experimental results support that the DLC-coated cutter in up cutting has good performance among four types of combination by the presence or absence of coating and the up/down cutting manner. They also showed that the tool life of DLC-coated cutter in up cutting under cutting speed of 157 [m•min-1] was corresponding to the cutting distance of 80 [m] with average width of flank wear 102 [μm] and that in down cutting was 60 [m] with 85 [μm]. In the range of cutting distance up to 100 [m], the resultant cutting force with the DLC-coated cutter was smaller than that with a non-coating cutter. In case of the DLC-coated cutter in up cutting under the cutting speed of 189 [m•min-1], a chatter vibration occurred during the initial cutting distance. In case of the radial depth of cut of 1.5 [mm], it lasted up to the cutting distance of 10 [m] and more.
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Authors: Seji Tsurimoto, Toshimichi Moriwaki, Masafumi Nagata
Abstract: Tungsten Carbide have extremely high hardness and wear-resistivity compared with conventional steel materials, and it is expected that the Tungsten carbide can be applied widely to dies and molds in the near future. In order to develop an efficient machining method of Tungsten Carbide for the dies and molds, series of cutting experiments were carried out to turn the sintered Tungsten Carbide materials with CBN tool. The selected sintered Tungsten Carbide workpieces are those containing Tungsten Carbide grains with mean grain size of 5μm, and 15wt%, 20wt% and 22wt% of Cobalt binder. The sintered CBN tool selected contains super-fine grains of CBN with mean grain size of 1μm. The cutting speed was varied from 10m/min to 60m/min, and the tool wear and the surface roughness were measured. It is concluded that the tool wear is less when cutting the sintered Tungsten Carbide containing larger amount of Cobalt binder. The surface roughness of about 2μm in Rz is obtained.
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Authors: Takuya Furukawa, Yosuke Nomura, Kazuyuki Harada, Kai Egashira
Abstract: The turning of straight micropins with a diameter smaller than 10 µm, which has not been reported so far, was carried out using micro turning tools made of cemented tungsten carbide. Tools of 50 µm diameter were fabricated by electrical discharge machining, which is suitable for fabricating micro cutting tools because it can deal with hard materials and carry out micromachining. A turning machine designed especially for micro turning tools was used in the experiments. A brass workpiece was turned using a tool with a length of cut of 100 µm at a feed speed of 3.0 µm/s, feed per revolution of 0.06 µm and depth of cut of 10–11 µm. As a result, a straight micropin of 7.5 µm diameter and 80 µm length was successfully turned. Furthermore, turning was also performed using a tool with a length of cut of 50 µm at a feed speed of 3.0 µm/s, feed per revolution of 0.06 µm and depth of cut of 8.5–20 µm to fabricate a straight micropin of 3 µm diameter and 30 µm length. This micropin is the pin with the smallest ever diameter fabricated by turning, to the best of our knowledge, indicating the possibility of further minimization of the machinable size in turning. Turning properties were also investigated to determine the maximum depth of cut and feed speed that can be employed without tool breakage.
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Authors: Yuya Kobaru, Eiji Kondo, Ryuichi Iwamoto
Abstract: A lot of studies on the ultra-precision cutting of single crystal silicon have been reported and they used the single crystal diamond cutting tools having the sharp cutting edge. However, the diamond cutting tools having small chamfer at the cutting edge are usually used in practical machining shops. In addition, studies on the relationship between the tool wear and the machined surface have been reported little although the relationship is important in practical applications. In this study, ultra-precision cutting of single crystal silicon, using cutting fluids, feed rate, and depth of cut as experimental parameters, were carried out by using the single crystal diamond cutting tools having small chamfer and large nose radius, and effects of the cutting fluids, the feed rate, and the depth of cut on the machining accuracy and tool wear were studied. As a result, the optimum cutting conditions was obtained as follows: the cutting fluid was kerosene, the feed rate was 2.0μm/rev, and the depth of cut was 1.0μm.
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Authors: Rong Bian, Eleonora Ferraris, Jun Qian, Dominiek Reynaerts, Liang Li, Ning He
Abstract: This work presents an experimental investigation on micro-milling of fully sintered Zirconia (ZrO2) with CVD diamond coated end mills. The experiments were conducted on a Kern MMP 2522 micro-milling centre. Diamond coated WC micro end mills with stiff geometry, are employed. Effects of cutting parameters on surface quality were investigated by means of a mixed full factorial experimental design. Surface roughness was measured by a Talysurf 120L profilometer. Surface topography was examined using a scanning electron microscope. The results show that a smaller feed rate was apt to result lower surface roughness. With the increase of cutting length, brittle damages were observed in some tests.
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Authors: German Herrera-Granados, Kiwamu Ashida, Ichiro Ogura, Yuichi Okazaki, Noboru Morita, Leopoldo Ruiz-Huerta, Alberto Caballero-Ruiz
Abstract: Micro-grooves fabrication is increasing due to its importance in different technology fields, as they are required for higher functional applications such as the development of optical lens or micro channels for heat exchangers. A novel method based on the technology developed for Atomic Force Microscopes (AFM) nano-cutting is proposed, where nano-scratches are made using a micro-cantilever with a sharp tip where a normal load sufficient to remove material is applied. Instead of a rigid system to control the relative position between the tool and the workpiece, AFM nano-cutting uses a force feedback control (FBC) of the normal load on the tool edge in order to maintain a constant cutting depth during the manufacture. Due to the limited scale range of AFM machining, a larger mechanism was developed and consists on a XYZ-stage system where an elastic leaf spring type tool holder is mounted with a diamond tool chip. FBC is not yet implemented on this system; however, basic experiments (micro-grooves cutting) were performed on different materials to verify the feasibility of this setup. With these results, it is possible to analyze the relationship between static indentation tests and the normal load required during the micro-grooves fabrication.
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Authors: Takashi Matsumura, Yuki Endo, Hideyuki Ozawa
Abstract: Sapphire has high mechanical strength at high temperatures and high pressure. Thus, micro devices made of sapphire are expected to be used in extreme environments such as aerospace, defense and marine. Then, the machining technology is required for manufacturing of 3 dimensional shapes. The paper discusses the micro cutting process of sapphire to determine the applicable cutting parameters in planing and milling. First, the critical stress at which crack initiation occurs is measured in the indentation test with detecting AE signal. The critical stress of sapphire is beyond 22.6 GPa, which is much higher than those of glasses. Then, the critical depths of cut, maximum depths of cut in which crack-free surfaces were finished, were measured in cutting of r crystal plane. The critical depth of cut is maximized when the cutting is performed in a crystal axis direction. In milling of sapphire, adhesion of chip onto the surface finish should be considered as well as brittle fracture. In milling of r crystal plane, the surface finish is improved better than those of the other crystal planes. Adhesion of material can also be controlled by supplying lubrication.
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