• 한국정밀공학회지
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• 제22권12호
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• pp.184-189
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• 2005

An experimental study of the femtosecond laser machining of Si materials was carried out. Direct laser machining of the materials for the feature size of a few micron scale has the advantage of low cost and simple process comparing to the semiconductor process, E-beam lithography, ECM and other machining process. Further, the femtosecond laser is the better tool to machine the micro parts due to its characteristics of minimizing the heat affected zone(HAZ). As a result of line cutting of Si, the optimal condition had the region of the effective energy of 2mJ/mm-2.5mJ/mm with the power of 0.5mW-1.5mW. The polarization effects of the incident beam existed in the machining qualities, therefore the sample motion should be perpendicular to the projection of the electric vector. We also observed the periodic ripple patterns which come out in condition of the pulse overlap with the threshold energy. Finally, we could machined the groove with the linewidth of below $2{\mu}m$ for the application of MEMS device repairing, scribing and arbitrary patterning.

• 한국정밀공학회지
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• 제26권7호
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• pp.44-50
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• 2009

High-pressured jetting is now widely used in the advanced cutting processes of polymers, metals, glass, ceramics and composite materials because of some advantages such as heatless and non-contacting cutting. Similarly to the focused laser beam machining, it is well known as a type of high-density energy processes. High-pressured jetting is going to be developed not only to minimize the cutting line width but also to achieve the short cutting time as soon as possible. However, the interaction behavior between a work piece and high-velocity abrasive particles during the high-pressured jet cutting makes the impact mechanism even more complicated. Conventional high-pressured jetting is still difficult to apply to precision cutting of micro-scaled thin work piece such as thin metal sheets, thin ceramic substrates, thin glass plates and TMM (Thin multi-layered materials). In this paper, we proposed the advanced high-pressured jetting technology by introducing a new abrasives supplying method and investigated the optimal process conditions of the cutting pressure, the cutting velocity and SOD (Standoff distance).

• Journal of Electrical Engineering and Technology
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• 제2권1호
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• pp.106-111
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• 2007

Laser cutting with the micro-control technique has great potential to be employed for acrylic machining. In this paper, the optimal conditions of acrylic etching have been investigated. The three parameters such as laser power, moving velocity, and thickness of acrylic are experimented to find out optimal conditions. From these experimental results, we have known that it is very important to control accurate power by the TRIAC switching technique. The best condition of acrylic etching is performed 10 Wand 72 mm/sec at the plastic thickness of 1.33 mm. The other case is performed 10 W and 48 mm/sec, and 12 W and 56 mm/sec at the acrylic thickness of 2.00mm, respectively.

• 한국공작기계학회논문집
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• 제10권4호
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• pp.97-103
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• 2001

The study on the high-speed machine tool is very important for the improvement of productivity since it can shortens cutting and non-cutting time. Especially, high speed of feed drive system is the major research field. In the industries of the advanced countries, the feed drive systems at the speed of 60 m/min have been already developed based on the high lead ball screws. In this study, a high speed feed drive system at the speed of 60 m/ min has been developed, and its movements characteris-tics are investigated. As the movement characteristics, positioning accuracy, angular accuracy, straightness and micro step-response are measured. Thermal characteristics of the system is also discussed. For measuring the movement characteris-tics, a laser interferometer, a memory-based Hi-coder and a cooling device are used. The experimental results confirm that the movement characteristics and the thermal behavior of the system are satisfactory in the aspect of accuracy and stability.

• Composites Research
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• 제22권6호
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• pp.7-12
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• 2009

본 연구는 압전 작동기 기반 초소형 날갯짓 비행체의 날갯짓 운동을 위해, 압전 작동기의 펌핑 운동을 효과적으로 날갯짓 운동으로 변환하는 힌지 메커니즘 제작 기법에 대해 다루었다. 경량화를 위해 탄소섬유/에폭시(Graphite/Epoxy) 프리프레그를 사용하고, 반복적인 제작이 용이하도록 레이저 절단기를 활용하였으며, 힌지부는 얇은 캡톤 필름을 이용해 컴플라이언트(compliant) 메커니즘으로 구성하였다. 제작된 힌지 메커니즘을 압전 유니모프 작동기 PUMPS에 연결하여 동작시켜 본결과, 300V 170Hz 인가 전압에서 $173^{\circ}$의 큰 날갯짓 각을 가짐을 확인하였다.

• 한국정밀공학회지
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• 제29권8호
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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.