• Journal of the Korean Society for Precision Engineering
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• v.22 no.6 s.171
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• pp.109-117
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• 2005

In case of fine machining processes, the cutting state monitoring by a skilled operator is impossible because the physical changes generated during fine machining are very weak. To realize the high efficient and precise fine machining, it is necessary to develop the sensor based monitoring system which is able to detect the fine changes of cutting state. In this paper, the fine acoustic emission monitoring system is developed to monitor the state of the fine machining process. The developed system consists of the AE sensor and the AE signal processing unit. And this has the high-sensitivity and bandwidth which can detect fine AE signal generated during fine machining process. In order to investigate the feasibility of the developed system, evaluation experiments were performed in the fine fixed-abrasive machining processes such as polishing and glass ferrule slicing. Experimental results show that the developed monitoring system possesses an excellent real-time monitoring capability at fine machining processes.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.12 no.6
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• pp.30-36
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• 2013

An FFD(flexible fine die) is an embossed mold that consists of a thin plate ranging from 0.6 to 3 mm in thickness. FFDs are primarily used for cutting LCD films and F-PCB sheets. In the high-speed micro-milling process of flexible fine dies, the lubrication and cooling of the cutting edges is very important from the aspect of eco machining and cutting performance. In this paper, a comparative study of tool wear and surface roughness between cutting fluid and hybrid lubrication for eco-machining of FFD was conducted for processes of high-speed machining of highly hardened material (STC5, HRC52). Especially, the incorporated fluid method for eco machining, in which the cutting performances can be simultaneously measured, was introduced. The machining results show that hybrid lubrication, instead of conventional cutting fluid, leads to excellent tool wear and surface roughness and represents the proper conditions for eco micro-machining of flexible fine dies.

• Transactions of Materials Processing
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• v.6 no.3
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• pp.192-202
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• 1997

This study presents an effect of number of passes in wire-cut electric discharge machining on fine blanking dies and products. Three part fine blanking dies were produced by the difference of numbers of passes discharge machining. Brake pad was produced, through the die produced like that, the objective of this study is the improvement in surface roughness of die block and punch, life extension of die block, the decrease of second fracture dimensions, the rise of productive.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2002.05a
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• pp.964-967
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• 2002

An internal finishing process by the application of magnetic abrasive machining has been developed as a new technology to obtain a fine inner surface of pipe. In this paper, another method of magnetic abrasive machining in which the N and S magnetic poles are feed and a workpiece is rotated only is tried in a fine-pipe, and its finishing characteristics is experimently investigated by various effective factors such as feeding amplitude. From the experimental results, it is found that the feed effects of magnetic poles on the finishing characteristics are large in internal finishing.

• Journal of the Korean Society for Precision Engineering
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• v.7 no.4
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• pp.40-54
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• 1990

Recently, Fine Ceramics have been concerned significantly with some excellent properties and many functions as new industrial materials to the industry at alrge. For the manufacture of Fine Ceramics, sintering is essential process. Thus the most of a Fine Ceramics used for precision parts are in need of machining proces. It is, however, very difficult to manufacture the Advanced Ceramics with high efficiency because they have not only high strength and brittl- eness but also high hardness. In present research, experiments are carried out to obtain the basic knowledge of Fine Ceramics grinding with high efficiency. Representative advanced ceramics, such as A1/sub 2/0/sub 3/, Z/sub r/O/sub 2/SiC snd Si/sub 2/N/sub 4/are ground with diamond wheels using conventional surface grinding machine. This research is carried out for the purpose of saving machining technology required for manufactiring Fine Ceramics parts

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.12 no.6
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• pp.10-16
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• 2013

Ultra-fine planing and micro punching are separately used for improving surface roughness and machining dot patterns, respectively, of metal molds. If these separate machining processes are applied for machining of identical molds, there could be an aligning mismatch between the machine tool and the mold. A hybrid machining system combining ultra-fine planing and micro punching was newly developed in this study in order to solve this mismatch; hybrid process technology was also developed for machining dot patterns on a mirror surface of a metal mold. The hybrid machining system has X, Y, and Z axes, and a cam axis for ultra-fine planing. The cam axis and attachable and removable solenoid actuators for micro punching can make large and small sizes of dot patterns, respectively. Ultra-fine planing was applied in the first place to improve the surface roughness of a metal mold; the measured surface roughness was about 20nm. Then, micro punching was applied to machine dot patterns on the same mold. It was possible to control the diameter of the dot patterns by changing the input voltage of the solenoid actuator. Before machining, severe inhomogeneous plastic deformation around the machined dot patterns was also removed by annealing heat treatment. Therefore, it was verified that metal molds with dots patterns for optical products can be machined using a hybrid machining system and the hybrid process technology developed in this study.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.25 no.1
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• pp.47-53
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• 2001

Results ar presented of a new process for internal precision finishing of slender fine ceramic pipes using a magnetic field generated by a permanent magnets. For finishing the interior surface of a long pipe, a new type of finishing equipment was developed which can be very easily used in an industrial surrounding. In general, the pipe is so slender that a conventional finishing tool is hardly inserted into the pipe deeply, being impossible to finish. Therefore, a new technology has been considered to finish inside of a slender ceramic pipe by a simple technique. In this experimental, Magnetic Abrasive Machining is applied for the inner surface of silicon nitride fine ceramic pipe using ferromagnetic particles mixed with chromium-oxide powder. It is shown the initial roughness of 2.6㎛ Ry(0.42㎛ Ra) in the inside surface can be precisely finished to the roughness of 0.1㎛ Ry(0.01㎛ Ra). This paper discusses the outline of the processing by the application of magnetic abrasive machining and a few finishing characteristics.

• Transactions of the Korean Society of Mechanical Engineers
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• v.14 no.5
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• pp.1147-1154
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• 1990

Micro-hole drilling by EDM and production of fine rods for the tool electrode or other purpose have become very important in industry. This paper suggests a new method for production of very fine rods by ultrasonic-assisted chemical machining and describes the machining characteristics of micro-hole drilling by EDM. For fine rods, copper wires of initial diameter of 250.mum are used and successfully machined into a diameter of less than 30.mum with good repeatability. The ultrasonic agitation not only accelerated the material removal rate uniformly, but also produced smooth surfaces of fine rods. To drill the micro-hole, kerosene and pure water is used as a dielectric. From the experiment, water is superior to kerosene with respect to surface roughness of inlet and outlet of hole and machined surface as well as electrode wear. However, due to the electrochemical reaction of water, small pits are remained on the workpiece surface.

• Design & Manufacturing
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• v.14 no.3
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• pp.63-70
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• 2020

As the consumer market in the VR(virtual reality) and the head-up display industry grows, the demand for 5-axis machines and grooving machines using on a ultra-precision machining increasing. In this paper, ultra-precision diamond tools satisfying the cutting edge width of 500 nm were developed through the process research of a focused ion beam. The material used in the experiment was a single-crystal diamond tool (SCD), and the equipment for machining the SCD used a focused ion beam. In order to reduce the influence of the Gaussian beam emitted from the focused ion beam, the lift-off process technology used in the semiconductor process was used. 2.9 ㎛ of Pt was coated on the surface of the diamond tool. The sub-micron tool with a cutting edge of 492.19 nm was manufactured through focused ion beam machining technology. Toshiba ULG-100C(H3) equipment was used to process fine-pattern using the manufactured ultra-precision diamond tool. The ultra-precision machining experiment was conducted according to the machining direction, and fine burrs were generated in the pattern in the forward direction. However, no burr occurred during reverse machining. The width of the processed pattern was 480 nm and the price of the pitch was confirmed to be 1 ㎛ As a result of machining.

• Journal of the Korean Society for Precision Engineering
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• v.29 no.8
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• pp.834-839
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• 2012

Recently, mechanical components with miniaturized size, complex shape and fine surface are on demand from industries such as mobile electronics, medical devices and defense. The size of them is smaller than several millimeters, the shape has micro-holes, curve, or multi-step and the surface is mirror-like. This features are not able to be machined with the conventional machining, therefore electro-discharge machining (EDM), cutting, and laser machining have been applied. If the technologies are assisted by vibration, high aspect ratio and good surface are to be achieved. In this paper, prior and current researches of vibration-assisted machining are reviewed. Machining mechanisms with vibration-assisting are explained, their effects are shown, and vibrating apparatuses are discussed. Especially, comparison between with and without vibration assisting is presented. This review shows the vibration-assisted machining is effectively fabricate the components with small and complicated shape and fine surface finish.