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장경천(K.C. Jang),이동길(D.G. Lee),정민관(M.G. Jung),김명호(M.H. Kim),김일수(I.S. Kim) 한국생산제조학회 2008 한국생산제조시스템학회 학술발표대회 논문집 Vol.2008 No.5
In this study, the objectives were to save cost, reduce molding cycle time and enhance the consistency of product dimensions of the insulating materials in Direct-Drive motor(DDM) use for one of the home appliances, the drum washing machine, compare to those of the existing one. Through reviewing the existing one's molding operating conditions, verifying it with molding analysis and optimizing the mold design and operating conditions applying the valve gate, and after test production, the following results were obtained. Due to weight reduction of the expensive material from 1,050g to 950g, the cost was reduced by 10%. The cycle time that includes heating of material, injection, cooling and ejection was reduced from 75sec to 50sec. The occurrence rate of the burned mark on the lower side of part was reduced to less than 1% by lowering the molding temperature from 285℃ to 270℃. The defect rate was reduced by 50% as the outer radial side of the part contraction and anisotropic deformation were reduce from the level of 1.2㎜ to 0.5㎜.
이동길(D.G. Lee),장경천(K.C. Jang),정민관(M.G. Jung) 대한기계학회 2007 대한기계학회 춘추학술대회 Vol.2007 No.10
The influence of Niobium(Nb) contents and aging conditions on the strength and fatigue life of 18%Ni maraging steel commonly using in aircraft, space field, nuclear energy, and vehicle etc. were investigated. The yield strength was the highest about 1,800MPa in 0.06%Nb specimen having twice as much as the base metal specimen. Also, the elongation was the highest in 0.03%Nb specimen showing the same as base metal specimen. The higher aging temperature and the longer aging time, the fatigue life increased. On the other hand, the 0.03%Nb specimen showed the highest fatigue life which increased about 12% more than base metal specimen. 0.06% Nb specimen aged at 482℃ for 8 hours simultaneously satisfied the 250 grade strength and 200 grade elongation having the most superior mechanical properties.
이동길(D.G. Lee),장경천(K.C. Jang),정민관(M.G. Jung),김명호(M.H. Kim),김일수(I.S. Kim) 한국생산제조학회 2008 한국생산제조시스템학회 학술발표대회 논문집 Vol.2008 No.5
MIM(Metal Injection Molding) that is a kind of PIM(Powder Injection Molding) is using in optical communication field, display field, several fields such as semi-conductor field because ceramic has superior physical properties. Also, mold's optimization that can produce high precision flange that is one of main parts of optical communication field is greatly required. The objective of this paper is to study the suitability of design and capability analysis for the MIM and process that can mass-produce the flange using in a mold by conduct the experiments as well as the flow analysis. It was filling time 0.5~1.5 second, injection pressure 11.0~12.5 ㎫ range for the injection parameters that cause high effect to injection derived from optimum condition by flow analysis. Yield that is more than gravity 7.495 that establish by target as result that analyze gravity of products at investigated injection conditions was 99.01 % and process capability was construed by 3.83 sigma level. Also, the average gravity and standard deviation was 7.6151 and 0.0511 respectively. The measured dimensions were all good results within the established target showing that concentricity, roundness, and density were 27.43 ㎛, 18.64, and 97.63%.
CIM 탈지공정 중 오염방지를 위한 필터 및 연소장치 제작 연구
장경천(K.C. Jang),이동길(D.G. Lee),김명호(M.H. Kim),정민관(M.G. Jung) 한국생산제조학회 2009 한국생산제조시스템학회 학술발표대회 논문집 Vol.2009 No.10
본 연구는 일반적인 현장에서 CIM(Ceramic Injection Molding)을 위하여 혼합된 P, EVA, CB 등의 바인더가 탈지공정에서 대기 중으로 방출되는 배기가스로 인하여, 작업공간의 오염 및 작업자에게 유해하며 환경오염이 발생되는 문제점을 해소 하고자 탈지로의 흡/배기구에 필터장치 및 2차 연소장치를 고안하여 제작하도록 하였다. 또한 사출이 완료된 사출성형체는 탈지로에서 탈지공정을 거쳐 성형체가 되고 이를 소결로에서 소결을 실시 후 검사하면 외관상에 흑점이 약 6%정도 발생되고 흑점 발생분에 대해서는 전량 폐기를 하고 있는 실정이다. 이러한 오염에 대한 근본적인 원인을 분석한 결과 갈색과 청색상의 결함부는 금속계 불순물과 Zr계 산화물에 의한 오염으로 조사되었으며, 이와같은 문제 해결을 위해 선정한 필터링 시스템은 Mesh 0.3 ㎛의 HEPA Filter를 시용한 시스템을 설계 및 제작하였다. 연소시스템을 설치하여 가동을 수차례 실시한 결과 기존에 발생되던 그을음 및 악취는 전혀 발생되지 않았으며, HEPA Filter(mesh 0.3 ㎛)를 이용한 필터시스템을 설치한 후 불량률은 평균 1.980%로서 개선전 대비 4.316% 오염에 의한 불량률이 감소되어 매우 효율적인 결과를 나타내었다.