Papers by Keyword: Micro-Hole

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Authors: Chandra Nath, Gary Ka Lai Ng, Gnian Cher Lim, Jeong Hoon Ko
Abstract: Structural SiC (α-type) is believed to be widely applied in hostile environments such as high-temperature, high-corrosive applications in the semiconductor industries due to its superior thermo-physical and mechanical properties. However, the extremely high hardness and brittleness of SiC makes hole drilling difficult by the conventional mechanical drilling (CMD) technique. Laser can be used to drill SiC; but the resultant holes are often tapered and uneven, with tendency for microcracks and thermal damage to occur at the hole entry due to the high thermal shock from the laser. This paper reports on the experimental results of a sequential laser-mechanical drilling (LMD) technique for drilling α-SiC. At first, an Nd:YAG laser was used to drill a series of pilot holes on a 3 mm thick SiC plate. Then a diamond-coated carbide drill was sequentially applied to these holes to obtain desired hole diameter of 0.5 mm. A number of through holes on SiC (aspect ratio: 6) were successfully obtained using this approach. The quality of the drilled holes were assessed in terms of the entrance and exit sizes and conditions, hole taper angle, hole edge shapes, and microcracks. Finally, comparisons of the LMD performances were also made against the holes predrilled by the laser itself and holes of the similar size drilled separately with the CMD technique. The experiment results show that the proposed drilling approach can effectively drill α-SiC ceramics.
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Authors: Jun Liang Yuan, Jin Gen Deng, Qiang Tan, Lian Bo Hu
Abstract: With the ever increasing energy demands, unconventional gas becomes the new force in energy field. However, shale gas horizontal drillings are prone to instability problems because of the brittleness of gas shale. The casing programs of shale gas wells in China and North America demonstrate that the more drilling problems are encountered with the larger borehole sizes. In the thrust faults, based on vutukuri's size effect theory and Mclamore's failure criteria, a new prediction model of collapse pressure in transversely isotropic rock mass is proposed to analyze the critical mud weight of micro-hole in gas shale formations. The trajectory sensitivity analysis is also carried out. The results show that micro-hole drilling technique in thrust faults can significantly reduce the collapse pressure of directional wells by 12% approximately.
410
Authors: Hiroshi Murakami, Akio Katsuki, Hiromichi Onikura, Takao Sajima, Norio Kawagoishi, Eiji Kondo, Tomohiro Honda
Abstract: This paper presents a system of 3-D micro structure measurement that uses an optical fiber probe of 5 µm in diameter. The probe is deflected when it comes into contact with a measured surface, and this deflection is measured optically. In this research, we optimize design parameters of optical system using ray tracing, and a prototype of the measuring system is fabricated on trial to verify the simulation results. Then, its measuring accuracies are examined by using the basic experimental apparatus. As a result, it is clarified that the resolution of the fiber probe is better than 10 nm. Also, the utility of this system is confirmed by measuring the shape of a 600 µm diameter ruby sphere.
524
Authors: Kun Ling Wu, Hsin Min Lee, Kuan Hwa Chin
Abstract: Electrochemical discharge machining (ECDM) is the preferred non-traditional process technology in recent years, The main processing is applied to machining non-conductive hard brittle materials. This study investigated the precision and stability of quartz fabricated by ECDM and explored the optimal processing parameters including size of electrode, machining speed as well as pulse-on and pulse-off duration. Microgrooves machined under the optimal processing parameters with adjusted rotational speed and feed rate were examined to understand the effect of different ECDM parameters on machining performance. The results indicate that micro-holes of better morphology could be obtained under pulse voltage of 40 V, electrolyte concentration of 5 M, electrode size of 125 μm. Moreover, rotational speed of 1500 rpm and pulse-on/pulse-off (ms) ratio of 1:0.6 gave higher machining accuracy with smaller hole diameter and shorter machining time. Finally, microgrooves machined under the optimal processing parameters showed the best accuracy in dimension and cross-sectional morphology at rotational speed of 2500 rpm, pulse-on /pulse-off (ms) ratio of 1:1.6, and feed rate of 3000 μm/min.
161
Authors: Bülent Ekmekci, Atakan Sayar, Tahsin Tecelli Öpöz, Abdulkadir Erden
Abstract: Micro Electric Discharge Machining is mostly used micromachining technique for manufacturing of micro holes and mini cavities. It is a thermal material removal process achieved by application of recursive electrical sparks between two conductive materials immersed in dielectric liquid. There are many electrical and technological parameters, which are effective in the machining characteristics and machined material surface integrity. In this study, effects of pulse energy on characteristics of surface damage in micro electric discharge machining of micro holes are investigated. To observe the influences of investigated pulse forms, a series of micro-holes were machined and cut from cross sections for metallurgical examinations. Unconventional etching agents were applied to examine the metallurgical transformations using optical and scanning electron microscopy. It was observed that heat-damaged segment is composed of three distinctive layers, have relatively high thicknesses (0.2 to 10 μm) when compared with the size of the micro holes and varies noticeably with respect to drilling dept. Different morphological structures and deformations in the subsurface of micro-hole walls at several sections were illustrated. Finally, analyzed machining parameters and variation of hat damaged layer thicknesses were discussed in terms of drilling depth.
688
Authors: Ming Gang Xu, Xue Ke Luo, Yong Li
Abstract: A new tool electrode high frequency vibration assisted micro-hole EDM machine tool aimed to resolve the problem of machine large quantities micro holes in industry was designed. The machine is mainly composed of main body, electrical control module and assistant mechanisms etc. And drawn tungsten wire was used as the micro tool electrode. A series of experiments were carried out using the micro-hole EDM machine.
430
Authors: Gao Liang Dai, F. Pohlenz, H.U. Danzebrink, L. Koenders
Abstract: Metrology plays an important role in the development and commercialisation of micro and nanotechnology. For calibrating versatile micro- and nanoscale standards, a dimensional metrology instrument coupled with multi sensor heads including atomic force microscope (AFM), tactile stylus, laser focus sensor and assembled cantilever probes (ACPs) has been developed. Two kinds of ACPs are highlighted in the paper. One is fabricated by gluing a vertical AFM cantilever to a horizontal AFM cantilever using micro assembling techniques. It is applicable for direct and non-destructive measurements of sidewall surfaces. The other is an ACP ball probe designed for true 3D measurements of micro structures. It is realised by gluing a tungsten wire with a probing sphere ball, 40 ... 120 µm in diameter, to a horizontal AFM cantilever. The ACP ball probe has advantages such as small probing forces (<1µN) and high probing sensitivity. Some typical calibrations on micro and nano structures such as step height, grating and sphere calotte artefact are introduced.
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Authors: Hui Chen, Zhen Long Wang, Zi Long Peng, Ying Huai Dong, Wan Sheng Zhao
Abstract: The purpose of this paper is to study electrochemical micro machining (ECM) technology on stainless steel. The micro machining of stainless steel is difficult by electrochemical machining, especially in machining deep micro holes, because of an oxide layer formed on the surface. To machining stainless steel, HF is usually used in electrolyte to destabilize the oxide layer. In this paper, ECM of stainless steel by applying short pulses in less toxic and corrosive electrolyte is research. The influence of electrochemical machining parameters such as voltage, current, electrolyte composition to machine stainless steel was investigated. The results showed that the oxide layer can be reduced by adding chloride and complex.
219
Authors: Bao Xian Jia, Dong Sheng Wang, Zhen Long Wang, Wan Sheng Zhao
Abstract: Experiments of combining micro EDM with USM are carried out to enhance the machining ability and flexibility of the micro EDM, improve the machining state, and increase the productivity and aspect ratio of the micro holes. Basing on RC pulse power supply and workpiece vibration, the micro holes are drilled. The results of comparing experiments indicate that in the processes of both micro EDM without USM and micro EDM with USM, the machining velocity and the wear of the electrode increase with the increase of open voltage and loop capacitance. The experiment results of amplitude influencing on the machining process indicate that with the increase of ultrasonic amplitude, the machining velocity heightens and the aspect ratio of the micro holes augments; at the same time, however, the wear of the electrode and the extensive magnitude of the holes increase. Micro holes with some cross-section and accurate profile are drilled steadily.
248
Authors: Zhi Yong Li, Zong Wei Niu, Li Li
Abstract: Electrochemical micro-machining (EMM) has become one of the main machining methods for production of miniaturized parts and components. Utilizing the developed EMM set-up, the effects of ultrasonic wave frequency on characteristics of localized dissolution and accuracy of micro-hole in EMM are investigated and evaluated. The experiment results demonstrate that the accuracy of micro-hole and characteristics of localized dissolution can become better with the increase of ultrasonic wave frequency. The accuracy of micro-hole machined by 26KHZ can improve about 30% than that by 16KHZ. Moreover, the ability of localized dissolution by 26KHZ can be increased about 27%-30%.
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