• Journal of the Korean Society of Manufacturing Process Engineers
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• v.16 no.1
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• pp.134-140
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• 2017

CFRP has many industrial applications due to its low weight and high strength properties. CFRP is a composite material composed of carbon fibers embedded in a polymer matrix; it provides excellent resistance to fatigue wear, corrosion, and breakage due to fatigue. It is increasingly demanded in aircraft, automotive, and medical industries due to its superior properties to aluminum alloys, which were once considered the most suitable for specific applications. The basic machining methods of CFRP are drilling and route milling. However, in the case of drilling, the delamination of each layer, uncut fiber, resin burning, spalling, and exit burrs are barriers to successful application. This paper investigates the occurrence of exit burrs when drilling holes with ultrasonic vibration. Depending on design parameters such as the point angle, the characteristics of hole drilling were identified and appropriate machining conditions were considered.

• Journal of the Korean Society for Precision Engineering
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• v.18 no.12
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• pp.152-158
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• 2001

In this paper, we have developed an electro discharge machine for micro drilling driven by a voice coil actuator. Because the voltage signal of the electro-discharging circuit shows a lot of peaks and valleys, the active type low-pass filtering technique is adopted to get the average of the signal. Since the motion of the voice coil is precisely controlled by the error value between the object voltage value and the measured one, it is possible to prevent the mechanical contact between the rotating electrode and the workpiece and to maintain the appropriate machining conditions during the process. The electro-chemical machining technology was also adopted to make small diameter electrodes. Pure water is used as a dielectric. The machining procedure is performed to verify the feasibility of the developed system. It takes about 10 seconds to drill the ${\phi}m$100${\mu}m$ hole to the 100${\mu}m$ thickness stainless steel plate. The machining time depends on the values of the resister and the capacitor. There may exist the optimal values of time constant and the tendency is displayed In the appendix.

• Journal of Ocean Engineering and Technology
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• v.13 no.1 s.31
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• pp.70-78
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• 1999

오늘날 기계공업 현장에서 심공드릴가공은 광범위한 응용과 양호한 생산성으로 인하여 그 요구가 증가 되고 있다. 그러므로, 본 연구는 난삭재인 SKD11고합금공구강을 여러가지 절삭조건하에서 BTA드릴가공하여 얻은 실험결과(표면조도, 진직도, 진원도, 원통도, 구멍확대량, 등)를 다루었으며 이들의 이론적 배경과 실험을 비교 분석하였다. 프레스금형 부품과 기계부품으로 사용되고 있는 SKD11고합금공구강은 기계가공이 힘든 난삭재료로서 그 어려움이 크므로 본 연구는 생산현장에 보다 나은 심공드릴가공결과와 관련 지식을 제공 할수 있다고 사료된다.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 1995.10a
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• pp.1075-1079
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• 1995

It is difficult to machine microparts, such as microshaft and microholes, by conventional machining. Such micropart can be easily machined by EDM because it's machining force is very low. In micro-EDM, the precise electrode movement and discharge energy control are important. Therefore, high precision motion stage and EDM device with high performance is necessary. In this research, a new EDM machine was developed and microshaft and microhole, with various shape and size, was machined.

• Proceedings of the KAIS Fall Conference
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• 2005.05a
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• pp.79-82
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• 2005

본 논문에서는 PCB의 제작 공정에 있어 기준구멍을 가공하기 위한 다축드릴머신의 PCB와 드릴날 간의 충돌시험을 구하여 설계에 반영한다. 이는 PCB 가공을 대량생산에 적합하고 정확성을 높이기 위해 PCB용 다축드릴 머신을 설계함에 있어 해석결과를 이용하여 안전성확보와 제작단가를 절감할 수 있다.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2012.10a
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• pp.633-634
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• 2012

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2010.05a
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• pp.231-232
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• 2010

• The Hankook-Saengyark Bo
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• no.249
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• pp.5-5
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• 2002

구기자 3품종 분양 병해충 강하고 다수확(청양시험장, 신청받아) - 참당귀육묘판 구멍 많을수록 좋다(수확량 늘고 생산비 절감효과 기대) - 신품종 '미강작약' 뿌리는 한약재로 꽃은 절화로 이용 - 1년만에 백출 생산할수 있다(농진청 작시, 재배기간 단축기술 개발) - 종자 가공$\cdot$품질관리센터 준공

• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.8 no.5
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• pp.115-120
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• 1999

This research is a described result of experimental for the parameter's effecting the microhole machining by Nd-Yag laser, The parameters are energy, pulse interval time a kin of assisting gas and its pressure. The result reveals that parameter value of energy 0.08J, pulse 20Hz, interval time of 300 microseconds could be a good machining condition to make upper microhoel that is the diameter range of 50-70${\mu}{\textrm}{m}$. At tat time the assistant gas such air, $O_2$, Ar $N_2$, was appelied. Assistant gas of air makes heat affected zone enlarge due to burning of material surface. Also it makes microhole irregular and damageable. Because of refusion caused by chemical reaction with $Al_2O_3$ ceramic material . The $O_2$(99.9%) has good characteristics to get good drilling and smooth surface on pressure of 0.2kgf/$\textrm{cm}^2$ but it is expensive. Ar, $N_2$ make material crack and burnning and proved that to be unappropriate but, Ar was a better than $N_2$.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2001.04a
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• pp.1072-1075
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• 2001

$Al_2O_3$ ceramics are generally used as components in processing equipment, devices or machinery because it can perform some functions better than competing metals or polymers. Many of these applications rely on $Al_2O_3$ ceramics special electromagnetic properties, its relative chemical inertness, hardness, strength and its temperature capabilities. But $Al_2O_3$ ceramics are brittle materials, a fact that may cause problems and at the same time be helpful while machining with laser. This study described a basic study of the input parameters effect on the dimension of the microhole at the $Al_2O_3$ ceramics using Excimer laser. In the laser microhole machining of $Al_2O_3$ ceramics, major input parameters are pulse energy, pulse power, pulse frequency and pulse numbers. In conclusion, we can get a smaller microhole and diameter rate by an appropriate pulse energy, pulse frequency and pulse number.