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CO₂ Laser에 의한 Polyamide-6 소결과 그 영향에 관한 연구
배성우(S. W. Bae),김동수(D. S. Kim),안영진(Y. J. Ahn),김형일(H. I. Kim),최기섭(K. S. Choi) 한국정밀공학회 2006 한국정밀공학회 학술발표대회 논문집 Vol.2006 No.5월
In the solid freeform fabrication (SFF) system using selective laser sintering (SLS), polyamide-12 powder is currently recognized as general material. In this study, some kinds of polyamide-6 powders with different shape and particlesize were fabricated to investigate the formability, the microstructure and mechanical properties. Also, to develop a more elaborate and rapid system, this study employs a new SLS device with a 3-axis dynamic focusing scanner system instead of the existing f θ lens used in commercial SLS. Polyamide-6 powders having the average size of 100 m were treated thermally in order to keep the spherical symmetry in shape. These polyamide-6 powders were mixed with polyamide-12 powders having the average size of 50 m to give the bimodal distribution of size. These mixed powders showed the better fabrication in the selective laser sintering process because the smaller particles of polyamide-11 played an important role in the compact packing of powders by filling the void space between the large particles of polyamide-6. Also, Experiments have performed to evaluate the effect of a scanning path and sintering parameters by fabricating the various 3D objects.
Si₃N₄계 세라믹 절삭공구의 절삭성능평가 및 회귀분석에 의한 공구수명 추정
안영진,고영목,권원태,김영옥 한국공작기계학회 2003 한국공작기계학회 추계학술대회논문집 Vol.2003 No.-
Four kinds of Si₃N₄-based ceramic cutting tools with different sintering time were fabricated to investigante the effect of sintering time on the microstructure, mechanical properties, grain sizes and the cutting performance. An endeavor was also made to determine the relation among mechanical property, grain size and tool life. Si₃N₄ home made cutting tool sintered for 1 hour under 1760° temperature and 25MPa pressure showed the best cutting performance among selected ceramic tools during machining both gray cast iron and heat treated SCM440. Multiple linear regression model was used to estimate the tool life from mechanical property, grain size and showed good result. It was also shown that hardness imposed the biggest effect on tool life.
안영진,고영목,권원태,김영욱 한국공작기계학회 2002 한국공작기계학회 춘계학술대회논문집 Vol.2002 No.-
This study is performed to develop the Si₃N₄ based ceramic inserts. Si₃N₄ with addition of SiC and Al₂O₃ is investigated to determine the possibility to be a new tool. The tool life of Si₃N₄ insert with more than 20wt% SiC is shorter than commercial Si₃N₄ insert during machining both heat treated SCM440 and gray cast iron. Even though SiC has higher hardness than Si₃N₄, its chemical affinity to the iron on high temperature may causes deterioration of tool life. To the contrary, Si₃N₄ insert with Al₂O₃ shows increase of tool life up to 300% compared to the commercial Si₃N₄ insert. It may attribute to the high temperature stability of Al₂O₃. Further study will be focused on the optimization of ceramic inserts with the composition of Si₃N₄ and Al₂O₃.
회귀분석에 의한 Si₃N₄계 세라믹 절삭공구의 공구수명 추정
안영진,권원태,김영욱 한국공작기계학회 2004 한국생산제조학회지 Vol.13 No.4
In this study, four kinds of Si₃N₄-based ceramic cutting tools with different sintering time were fabricated to investigate the relation among mechanical properties, grain size and tool life. They were used to turn gray cast iron at a cutting speed of 330m/min and depth of cut of 0.5mm and Imm in dry, continuos cutting conditions. Multiple linear regression model was used to determine the relations among the mechanical property, grain size and the density. It was found that the combination of hardness and fracture toughness showed a good relation with tool life. It was also shown that hardness was the most important single element for the tool life.