• Title/Summary/Keyword: Laser

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Laser Preheating Method for Three-Dimensional Laser Assisted Milling (3차원 레이저 보조 밀링을 위한 레이저 예열 방법에 관한 연구)

  • Oh, Won-Jung;Lee, Choon-Man
    • Journal of the Korean Society for Precision Engineering
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    • v.32 no.12
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    • pp.1031-1037
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    • 2015
  • Laser assisted machining (LAM) is an effective method with which to effectively process difficult-to-cut materials. Simple machining processes, such as turning and linear tool paths, have been studied by many researchers. But, there are few research efforts on LAM workpieces using threedimensional shapes because of difficulties controlling the laser heat on workpieces with inclined angles or curved surfaces. Two methods for machining three-dimensional workpieces are proposed in this paper. The first is that the heat source shape and laser focal length are maintained using an index table. Second, a rotary type laser module is controlled using an algorithm to move the laser heat source in all directions. This algorithm was developed to control the rotary type laser module and the machine tool simultaneously. These methods are verified by a CATIA simulation.

Analytical Study of the Determination of Distance between the Laser Heat Source and Tool for Laser-Assisted Machining (레이저보조가공에서 열원과 공구 사이의 거리선정을 위한 해석적 연구)

  • Baek, Jong-Tae;Lee, Choon-Man
    • Journal of the Korean Society for Precision Engineering
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    • v.32 no.8
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    • pp.699-704
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    • 2015
  • Laser-assisted machining has shown its potential to significantly improve product quality and reduce manufacturing costs; additionally, laser-assisted turning (LAT) and laser-assisted milling (LAM) have been studied by numerous researchers. A research study on the determination of the distance between the laser heat source and the tool for laser-assisted machining, however, has not yet been attempted; we conducted such an analysis by using a finite-element method and heat-transfer equation. The results of this analysis can be used as a reference for the determination of the distance between the laser heat source and the tool for laser-assisted machining.

Production of CO2 Laser Forming Machine for Bending of Sheet Metal Using the FE-Analysis (유한요소해석을 이용한 박판 벤딩용 CO2 레이저 성형기 제작)

  • Ko D.C.;Lee C.J.;Kim B.M.
    • Transactions of Materials Processing
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    • v.15 no.4 s.85
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    • pp.319-325
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    • 2006
  • The laser forming process is a new flexible forming process without forming tools and external force, which is applied to various fields of industry. Especially, applications of the laser forming process focused on cutting, welding and marking process. In this paper, the laser bending process of sheet metal which is heated by laser beam and formed by internal stress is simulated by using thermo elastic-plastic analysis model. Based on the result of FE-analysis, the laser bending machine is made to obtain reliable data for sheet bending. Under the same condition as FE-analysis, the laser bending experiment has been performed to ver 펴 the result of FE-analysis and good agreement has been obtained between FE-analysis and experiments. Additional laser bending experiments have been performed to evaluate the laser bending machine.

A Study on Laser Ablation of Copper Thin Foil by 355nm UV Laser Processing (355nm UV 레이저를 이용한 구리 박판 가공 시 어블레이션에 관한 연구)

  • Oh, Jae-Yong;Shin, Bo-Sung
    • Journal of the Korean Society for Precision Engineering
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    • v.24 no.2 s.191
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    • pp.134-139
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    • 2007
  • Usually nanosecond pulsed laser processing of metal is mainly affected by the thermal ablation. Many studies of the theoretical analysis and modeling to predict the laser ablation of metal are suggested on the basis of the photothermal mechanism at higher laser fluence. In this paper, we investigate the etching depth and laser fluence of laser ablation of copper foils and propose the simplified SSB Model(Srinivasan-Smrtic-Babu model) to study the photothermal effect of nanosecond pulsed laser ablation. The experimental results show that the photothermal ablation of the 355nm DPSS $NdYVO_{4}$ laser is useful to process the copper thin foils.

The excimer laser ablation of PET for nickel electroforming (니켈 전주도금을 위한 PET의 엑시머 레이저 어블레이션)

  • Shin, Dong-Sik;Lee, Je-Hoon;Seo, Jung;Kim, Do-Hoon
    • Laser Solutions
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    • v.6 no.2
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    • pp.35-41
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    • 2003
  • In this study, manufacturing of polymer master and mold insert for micro injection molding was investigated. Ablation by excimer laser radiation could be used successfully to make 3-D microstructure of PET. The mechanism for ablative decomposition of PET with KrF excimer laser(λ: 248nm, pulse duration: 5ns) was explained by photochemical process. And this process showed PET to be adopted in polymer master for nickel mold insert. Nickel electroforming by using laser ablated PET master was preferable for replication method. Finally, it was shown that excimer laser ablation can substitute for X-ray lithography of LIGA process in microstructuring.

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Investigation of acoustic monitoring on laser shock cleaning process (레이저 충격파 클리닝 공정에서 음향 모니터링에 관한 연구)

  • 김태훈;이종명;조성호;김도훈
    • Laser Solutions
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    • v.6 no.2
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    • pp.27-33
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    • 2003
  • A laser shock cleaning technology is a new dry cleaning methodology for the effective removal of small particles from the surface. This technique uses a plasma shock wave produced by a breakdown of air due to an intense laser pulse. In order to optimize the laser shock cleaning process, it needs to evaluate the cleaning performance quantitatively by using a monitoring technique. In this paper, an acoustic monitoring technique was attempted to investigate the laser shock cleaning process with an aim to optimize the cleaning process. A wide-band microphone with high sensitivity was utilized to detect acoustic signals during the cleaning process. It was found that the intensity of the shock wave was strongly dependent on the power density of laser beam and the gas species at the laser beam focus. As a power density was larger, the shock wave became stronger. It was also seen that the shock wave became stronger in the case of Ar gas compared with air and N$_2$ gas.

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The Study on Wafer Cleaning Using Excimer Laser (엑사이머 레이저를 이용한 웨이퍼 크리닝에 관한 고찰)

  • 윤경구;김재구;이성국;최두선;신보성;황경현;정재경
    • Proceedings of the Korean Society of Precision Engineering Conference
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    • 2000.05a
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    • pp.743-746
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    • 2000
  • The removal of contaminants of silicon wafers has been investigated by various methods. Laser cleaning is the new dry cleaning technique to replace wafer wet cleaning in the near future. A dry laser cleaning uses inert gas jet to remove contaminant particles lifted off by the action of a KrF excimer laser. A laser cleaning model is developed to simulate the cleaning process and analyze the influence of contaminant particles and experimental parameters on laser cleaning efficiency. The model demonstrates that various types of submicrometer-sized particles from the front sides of silicon wafer can be efficiently removed by laser cleaning. The laser cleaning is explained by a particle adhesion model. including van der Waals forces and hydrogen bonding, and a particle removal model involving rapid thermal expansion of the substrate due to the thermoelastic effect. In addition, the experiment of wafer laser cleaning using KrF excimer laser was conducted to remove various contaminant particles.

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Micro-machining of nickel by picosecond laser ablation (피코초 레이저를 이용한 니켈의 미세가공 특성)

  • Shin D.S.;Lee J.H.;Suh J.;Noh J.W.;Chung Y.W.;Kim J.C.
    • Proceedings of the Korean Society of Precision Engineering Conference
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    • 2006.05a
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    • pp.653-654
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    • 2006
  • In case of ultrashort laser ablation of metals, the transfer of energy from the electronic system causing strong absorption of laser light to the lattice needs relaxation times of the order of some picoseconds. Under the above theoretical background, nickel was ablated using femtosecond, picosecond and nanosecond laser. As a result, nickel ablation by picosecond laser and femtosecond laser, which are called ultrashort laser, has similar machinability because of relaxation time of metals, whereas nanosecond Nd:YAG laser has lower absorption, higher thermalization effect in comparison with ultrashort laser.

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Visualization of weld plume using high-speed holography (고속 홀로그래피에 의한 용접 플룸 거동의 가시화)

  • 백성훈;박승규;김민석;정진만;김철중
    • Journal of Welding and Joining
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    • v.17 no.1
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    • pp.71-76
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    • 1999
  • The real-time holographic interferometer with digital high-speed camera is applied to the experimental study of laser induced plasma/plume in pulsed Nd:YAG laser welding. A pulsed Nd:YAG laser with 1.2 kW average power is applied to generate laser induced plume. The recording speed of the high-speed camera is 3,000 f/s. The high speed photographs of weld plume without another visualization method, are compared with the visualization photographs with holographic interferometer. The radiation intensity from the laser induced plume is recorded by the high speed photographs, which fluctuated during laser radiation and disappeared after laser end. The density distribution of the plume is recorded by the holographic visualization method. The experimental results show the process of generation of the laser induced plasma/plume, and give the feasibility of quantitative measurement of laser induced plume in laser welding.

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Study of clean laser decapsulation process (친환경 레이저 디캡슐레이션에 관한 연구)

  • Hong, Yun-Seok;Mun, Seong-Uk;Nam, Gi-Jung;Choe, Ji-Hun;Yun, Myeon-Geun
    • Proceedings of the Korean Society of Laser Processing Conference
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    • 2006.11a
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    • pp.103-107
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    • 2006
  • Decapsulation of EMC(Epoxy Molding Compound) in package device is a method used to inspect inside of device by removing plastic molding. So far, chemical etching and mechanical grinding methods have been used widely. Recently, several works using laser have been carried out. This method has advantages with fast process time and precision than conventional methods because of noncontact process. Also, laser process is a clean process because of removing EMC directly without using toxic chemicals. The wavelength of laser used in this study is 355nm. Key parameters of removing EMC are laser power, scan speed, and number of scans of laser. It if confirmed that laser decapsulation is a useful process to inspect inside a device with a small thermal damage to chip surface.

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