• Proceedings of the Korean Society of Precision Engineering Conference
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• 1997.10a
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• pp.969-972
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• 1997

Ultrasonic machining technology has been developed over recent years for he manufacture of cost-effective and quality-assured precision parts for several industrial application such as optics, semiconductors, aerospace, and automobile application. The past decade has seen a tremendous in the use of ceramic in structural application. The excellent thermal, chemical and wear resistance of these material can be realized because of recent improvement in the overall strength and uniformity of advanced ceramics. Ultrasonic machining, in which abrasive particles in slurry with water are presented to the work surface in the presence of an ultrasonic-vibrating tool, is process which should be of considerable interest, as its potential is not limited by he electrical or chemical characteristics of the work material, making it suitable for application to ceramics. In order to improve the currently used ultrasonic machining using ultrasonic energy, technical accumulation is needed steadily through development of exciting device of ultrasonic machine composed of piezoelectric vibrator and horn. This paper intends to further the understanding of the basic mechanism of ultrasonic machining for brittle material and ultrasonic machining of ceramics based in the fracture-mechanic concept has been analyzed.

• Journal of the Korean Society for Precision Engineering
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• v.6 no.4
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• pp.11-20
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• 1989

마이크로 일렉트로닉스(Microelectronics)를 중심으로 하는 산업혁명이 진행되고 있는 시점에서 전자, 광학 또는 신소재 부품에 대한 형상과 치수 또는 표면거칠기에 대한 정확도와 정밀도가 엄격하게 요구되고 있다. 예를 들어 경취 재료인 반도체의 웨이화( w-afer), 수정진동자 자기헷트, 비구면렌즈 또는 연질 금속의 레이저빔(Laser Beam) 프린터 용 포리곤 밀러(Polygon Mirror), 자기디스크, 복사기용 드럼(drum), 레저기기용 반사밀러 등 가공정밀도를 향상시키기 위해서는 과거의 가공기술을 대치할 수 있는 새로운 초정밀가공 기술의 도입이 활발하게 진행되고 있다. 경취성 재료의 초정밀가공은 지금까지는 랩핑(lappi- ng), 폴리싱(polishing)의 가공기술이 주체였으나, 최근의 엄격한 부품정밀도에 대응하기 위하여 전가공을 초정밀 연삭가공으로 평면도,표면거칠기, 가공변질층을 향상시키고 다듬질 가공은 폴리싱으로 하여 표면거칠기를 향상시켜야 하는 가공기술이 보급되고 있다. 일반연질 금속의 다듬질가공은 유리지립을 이용하는 랩핑이나 폴리싱으로 다듬질 가공을 진행하고 있었 으나 형상정도와 표면정밀도를 동시에 얻는다는 것이 어렵고 또 가공시간이 너무 길어서 매우 고가인 것이 되고 말았다. 그러나 유리에서 연질금속으로 재료를 전환시키고 저가격화, 양산 화의 요구, 정밀도 향상과 부품의 안정화 등등 여러 이유로서 다아아몬드(Diamond) 공구로 mirror surface 를 만드는 초정밀 경면연삭 가공기술(precision turning with diamond)의 발달 로 이제는 완전히 새로운 가공기술로 대치되고 말았다. 다이아몬드에 의한 초정밀절삭은 공구 끝이 매우 예리하고 마모가 매우 적은 단결정 다이아몬드를 이용하고 절삭가공 기계는 운동정도 를 피가공물에 정확히 전사 시키는 방법이며 따라서 가공기계는 고도의 운동정밀도가 요구되며 그외에 강성, 진동, 열변이, 제어면에서 엄격한 검도가 있어야 한다.

• Korean Journal of Materials Research
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• v.11 no.10
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• pp.907-911
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• 2001

In order to improve the grindability of magnetic abrasive, Fe-WC magnetic abrasives were made by a plasma melting method after ball milling at various times. This study aims to investigate homogeneously distributed hard phases in Fe matrix and strong bonding between the Fe-matrix and the hard phase. According to XRD, SEM and OM observation, Fe-WC magnetic abrasive powders exhibit the best grindability by plasma melting for 30h ball milling. As a result of magnetic abrasive polishing, the surface roughness, R_{max}$ 5.0$\mu\textrm{m}$, before magnetic abrasive polishing, was reduced to R_{max}$ 2.4$\mu\textrm{m}$. The new magnetic abrasive polishing process is thought to be the useful methods for the automation of three dimensional surface polishing.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2002.10a
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• pp.250-253
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• 2002

The operation of surface and edge finishing is the last and essential process of parts machining, because a product is completed as an assembly. Therefore, the quality of the finished parts has a direct effect upon the performance of the product. Especially, the edge quality depending on the burr control process is very important. A number of deburring processes have been developed for macro burrs such as barreling, brushing, chemical methods, etc. However, micro burr removal when piercing a very thin plate is very difficult, because this badly deteriorates the surface quality of the processed part. When ultrasonic wave is propagated in liquids, it forms an infinitude of micro bubbles. These bubbles generate extremely strong force, which removes micro burrs. In ultrasonic micro deburring, the problem is that burrs are not removed completely, because only components of the explosive force directly act on the burrs, which is not enough. An attempt was made to remove the burrs using ultrasonic vibration in water with SiC as an abrasive agent. Because of the abrasive, smoother edges have been achieved. There are many control parameters in ultrasonic deburring such as abrasive size, ultrasonic frequency and amplitude, distance between tool and workpiece, tilt angle of workpiece etc. This study focuses on how distance and tilt angle influence deburring effect. A number of experiments for these parameters have been carried out, and then the effect of each parameter analyzed.