• 한국정밀공학회지
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• 제17권2호
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• pp.43-50
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• 2000

A CBN wheel was used for the highly efficient and precision grinding of the mold material(STD11). The grinding form accuracy by a CBN wheel is very excellent due to its low wheel wear, but grinding fragments resemble fine powders rather chips. A fine powders by this fragmentation can easily get attached to the wheel surface and therefore causing a loading. In order to prevent this fragmentation phenomena, the alumina stick is use to processing. Because the dressing with alumina stick should be interrupted for a processing, the automation of the processing and high productivity was very difficult. The investigation on the effect of Ultrasonic In-Process Dressing(ULID) on the grinding characteristics focuses in this Paper. This ULID method is that ultrasonic vibration in my Position of wheel is used to remove impurities on the wheel surface. Finally, the rate of surface roughness change in grinding by the ULID method was less than grinding without ultrasonic vibration. Loading phenomena by the ULID method were more prevented than grinding without ultrasonic vibration.

• 한국정밀공학회지
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• 제19권12호
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• pp.171-178
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• 2002

With increasing the needs for micro and precision parts, micro machining technology using micro tools has been studied to fabricate a small part with high density such as electronics, optics, communications, and medicine industry more than before. Though these micro tools have developed rapidly, it is difficult to apply them to micro fabrication technologies, because of the inherent manufacturing. In this study, micro tools (WC) to produce micro structures and parts were manufactured by cylindrical grinding machine employing ELID (Electrolytic In-process Dressing) technique and the micro tools are fabricated as square shape with the dimension less than 100${\mu}{\textrm}{m}$. With the micro tools on the same machine, characteristics of micro grooving and drilling are evaluated. Also we compare normal micro machining with ultrasonic micro machining on the vibration table. It is confirmed that the developed micro tools are fully applicable to micro grooving, micro drilling and free form cutting.

• 한국기계가공학회지
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• 제14권3호
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• pp.149-154
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• 2015

This study has focused on the deburring technology of a vacuum plate for MLCC lamination using electrolytic in-process dressing (ELID) grinding, and the magnetic-assisted polishing (MAP) process. The surface of the vacuum plate has many micro-holes for vacuum suction. They are easily blocked by the burrs created in the surface-flattening process, such as the conventional grinding process. In this study, the MAP process, the ELID grinding process, and an ultrasonic vibration table are examined to remove the micro-burrs that lead to the blockage of the holes. In the results of the experiments, the MAP process and ELID grinding technology showed significant improvements of surface roughness and deburring performance.

• 한국정밀공학회지
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• 제30권12호
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• pp.1237-1243
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• 2013

This study has focused on the effect of ultrasonic vibration table in ELID grinding process of aluminum nitride ceramics. Aluminum nitride ceramics has superior physical and chemical properties and widely used in IC, LSI substrate, package and so on. To achieve the high effective machining of brittle and high strength ceramics as like aluminum nitride, machining method combined ELID grinding and ultrasonic vibration has been adopted in this study. From the experimental results, material removal rate, MRR has been increased maximum 36 percent and spindle resistance has been decreased in using ultrasonic table. Surface roughness of ground surface became a little worse in using ultrasonic table but was somewhat improved in feed direction.

• 한국기계가공학회지
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• 제12권4호
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• pp.75-80
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• 2013

Single crystal sapphire being used in high technology industry is a brittle material with a high hardness and excellent physical properties. ELID(Electrolytic In-Process Dressing) grinding technology was applied to material removal machining process of single crystal sapphire wafer. Ultrasonic vibration which added to material using ultrasonic table was adopted to efficient ELID grinding of sapphire materials. The evaluation of the ground surface of single crystal sapphire wafer was carried out by means of surface measuring by using AFM(Atomic Force Microscope), surface roughness tester and optical microscope device. As the results of experiment, it was shown that more efficient grinding was conducted when using ultrasonic table. In case of using #170 grinding wheel, surface roughness of ELID ground specimen in using ultrasonic table was superior to ELID ground specimen without ultrasonic table. However, In case of using #2000 grinding wheel, surface roughness of ELID ground specimen in using ultrasonic table was inferior to ELID ground specimen without ultrasonic table.

• 보존과학회지
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• 제28권3호
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• pp.235-245
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• 2012

이 연구에서는 경북 영양 용화광산 선광장(등록문화재 제255호)을 대상으로 비파괴 훼손도 진단을 실시하였다. 훼손지도를 작성하여 구조물에 대한 훼손상태를 파악한 결과, 6열과 7열 구조물을 기점으로 하여 용화광산 선광장 상부(7~13열)에서는 생물, 토사에 의한 훼손율이 높은 반면 하부(1~6열)에서는 탈락, 균열, 표면변색의 훼손율이 매우 높게 나타났다. 이는 기계적인 공정과 화학적인 공정이 동시에 진행되는 하부 구조물에서 화학용액들이 구조물의 콘크리트와 반응하면서 물리화학적 풍화작용을 촉진시켰기 때문으로 판단된다. 선광장 구조물의 물성을 파악하기 위해 초음파속도를 측정한 결과, 평균 초음파속도는 2,462m/s(압축강도 $529kgf/cm^2$)로 측정되었다. P-XRF를 활용한 표면변색 오염물질의 분석에서는 용화광산에서 채굴하였던 광석들의 주요성분(Cu, Zn, Pb, Fe, As)과 동일한 것으로 나타났다. 선광장 주변 토양에는 Cu, Zn, Pb, As와 같은 중금속의 함량이 상당히 높았다. 이와 같은 성분들은 선광장 구조물뿐만 아니라 자연환경에도 영향을 줄 수 있기 때문에 구조물의 보존처리와 함께 토양의 정화도 병행해야 할 것이다.

• Journal of Welding and Joining
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• 제31권4호
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• pp.73-79
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• 2013

Burr grinding, Tungsten Inert Gas (TIG) dressing, ultrasonic impact treatment, and peening are used to improve fatigue life in steel structures. These methods improve the fatigue life of weld joints by hardening the weld toe, by improving the bead shape, and by creating the compressive residual stress. In this study, a new post-weld treatment method improving the weld bead shape and metal structure at the welding zone using Friction Stir Processing (FSP), a welding process, is proposed to enhance fatigue life. For that, a pin-shaped tool and processing condition employing Friction Stir Processing (FSP) is established through experiments. Experimental results revealed that fatigue life is improved by around 50% compared to as-welded fatigue specimens by reducing the stress concentration at the weld toe and by generating a metal structure finer than that of flux-cored arc welding (FCAW).