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알루미늄 표면 전처리에 따른 양극 산화 효과에 관한 연구
김기범(K. B. Kim),하석재(S. J. Ha),조명우(M. W. Cho),조용규(Y. K. Cho),김병찬(B. C. Kim) 한국소성가공학회 2015 금형가공 심포지엄 Vol.2015 No.8
In industry field, anodizing process of aluminum is used for not only coloring but also increase hardness of surface. Anodized aluminum is mostly used for cover of personal electronic device like mobile phone, portable battery. It is because of aesthetic and weight lightening of products. Through anodizing process, nano scale pore is formed on aluminum surface. These pores are used for fabrication diffused reflective film of display panel and CNT(Carbon Nano Tube). Anodizing pores are influenced by purity, surface roughness of aluminum and experimental conditions. In this study, use film polishing system and MR polishing system for pre-process of aluminum. Film polishing system use abrasive film that similar to sandpaper. During polishing process abrasive film is exchanged sequentially through motorized roller. So can maintain uniform condition of abrasive that involved in polishing process. Also, film polishing system have vibration module that increase polishing efficiency. MR polishing system use MR fluid that is made of CI powder. Cl powder is magnetic particle, so MR fluid can be changed viscosity through magnetic field. To increase material removal ratio, we add abrasive particle during polishing process. Both film polishing and MR polishing is improve surface roughness, but MR polishing is better than film polishing in terms of surface roughness. After polishing process, we conduct anodizing process to both case. In case of anodizing pore, MR polishing aluminum is better than film polishing aluminum. As a result of anodizing process, we confirm pre-process conditions can effect on anodizing process and pore formation.
MR polishing 적용을 위한 CI particle 크기에 따른 MR fluids의 유변학적 특성 분석
홍광표(K. P. Hong),이정원(J. W. Lee),하석재(S. J. Ha),조용규(Y. K. Cho),조명우(M. W. Cho),제태진(T. J. Je) 한국소성가공학회 2012 한국소성가공학회 학술대회 논문집 Vol.2012 No.10
MR (magnetorheological) fluids have been used to ultra-precision polishing optical glass and/or mold metal materials MR fluids were composed with CI particles (magnetic particle), DI water (carrier fluid), Na₂CO₃, Glycerin (stabilizer). In this study, the rheological properties of MR fluids which nano CI particles are dispersed were considered to compare the effects of micro sized CI particles, and MR polishing experiments were performed to evaluate the polishing properties of two types MR fluids. MR fluids based on two types of CI particle with different average size, 3.5㎛, 300㎚, were prepared. SEM, particle analyzer, and rheometer were utilized to investigate their rheological properties Sedimentations of MR fluids were measured to investigate the effects of dispersion stability. Finally, it was obtained the rheological properties (viscosity, shear stress, sedimentation) of MR fluid with larger particle size.
MR fluid jet polishing system의 비구면 렌즈 금형 코어 연마를 위한 경로
김기범(K. B. Kim),조명우(M. W. Cho),하석재(S. J. Ha),조용규(Y. K. Cho),이정원(J. W. Lee) 한국소성가공학회 2015 금형가공 심포지엄 Vol.2015 No.8
MR fluid can be changed viscosity through magnetic flied and that characteristic reduce scattering of jetting fluid. From this reason MR fluid jet polishing system can carry out ultra-precision polishing. In this paper we calculate path considering aspherical lens profile equation and experimental conditions of MR fluid jet polishing system. And then we polished aspherical lens mold core using MR fluid jet polishing system through path control and compare results before and after polishing process.
Micro End-milling과 MR fluid Jet Polishing을 이용한 도광판 마이크로채널 제작
이정원(J. W. Lee),하석재(S. J. Ha),홍광표(K. P. Hong),조용규(Y. K. Cho),조명우(M. W. Cho),제태진(T. J. Je) 한국소성가공학회 2012 금형가공 심포지엄 Vol.2012 No.9
Micro parts can be shown its difference of performance according to the surface integrity of final products. Micro burrs which are taking place from micro cutting should remove for the improvement of surface integrity. To resolve this problem, studies for micro deburring have performed actively. Nickel and Brass are commercially used as the LGP (light guide plate) mold materials of three-dimensional optical device for mobile display due to its corrosion and chemical resistance. In this study, micro endmilling process was carried out to generate the burrs, and then the burr height was measured by using microscope. MR jet deburring process was performed onto the edges of nickel and brass by MR jet polishing method which can control the process from the viscosity control of cohesive MR fluid under the applied magnetic field. The jet angle (0°, 30°) and deburring time (1min, 3min, 5min) were chosen as process parameters. Burr height was investigated to draw a conclusion. It was obtained that the deburring result at 0° was better than that of 30°. Finally, all of burrs were eliminated at 0° after 5min.
MR fluid Jet Polishing 시스템을 이용한 금형코어재료 연마특성에 관한 연구
이정원(J. W. Lee),하석재(S. J. Ha),홍광표(K. P. Hong),조용규(Y. G. Cho),여인규(I. G. Yeo),조명우(M. W. Cho),제태진(T. J. Je) 한국소성가공학회 2012 금형가공 심포지엄 Vol.2012 No.9
Ultra-precision polishing method by using MR fluid was come into the spotlight for the polishing of metal and optical materials. MR jet polishing process can be controlled by changing the viscosity of MR fluid according to imposed magnetic field. The used MR fluid for MR jet polishing process is composed with the mixture of CI particles, DI water, Na₂CO₃, and glycerin. The results can be obtained from the polishing parameters, such as polishing time, magnetic field, stand-off distance, pressure, etc. In this paper, MR jet polishing was applied to polish the nickel and brass surface with the corrosion and chemical resistance. Nickel and Brass mold materials have been used to fabricate the BLU (back light unit) for three-dimensional optical device in mobile display industries. The polishing results were investigated with the polishing time changing. In case of the MR jet polishing, ferromagnetic materials can be able to interrupt due to the cohesive MR fluid more than non-ferromagnetic materials during MR jet polishing. As the results, the surface roughness of brass (Ra=1.82㎚) was better than the one of nickel (Ra=2.24㎚) after 20min.