• Korea-Australia Rheology Journal
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• 제21권1호
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• pp.17-25
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• 2009

We studied the flow characteristics of the polymer melt in the injection molding process with ultrasonic vibration by using the numerical analysis. To minimize the error between the experimental data and numerical result, we presented a methodology using the design of experiments and the response surface method for reverse engineering. This methodology can be applied to various fields to obtain a valid and accurate numerical analysis. Ultrasonic vibration is generally applied between an extruder and the entrance of a mold for improvement the flow rate in injection molding. In comparison with the general ultrasonic process, the mode shape of the mold must be also considered when the ultrasonic vibration is applied on the mold. The mode shape is defined as the periodic and spatial deformation of the structure owing to the effect of the vibration, and it varies greatly according to vibration conditions such as the forcing frequency. Therefore, we considered new index and found the forcing frequency for obtaining the highest flow rate within the range from 20 to 60 kHz on the basis of the index. Ultimately, we presented the methodology for not only obtaining a valid and accurate numerical analysis, but also for finding the forcing frequency to obtain the highest flow rate in injection molding using ultrasonic vibration.

• 대한기계학회논문집A
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• 제26권11호
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• pp.2342-2354
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• 2002

The present study has numerically predicted both the flow -induced and thermally-induced residual stresses and birefringence in injection o. injection/compression molded center -gated disks. Analysis system for entire molding process was developed based on an ap propriate physical modeling including a nonlinear viscoelastic fluid model, stress-optical law, a linear viscoelastic solid model, free volume theory for density relaxation phenomena and a photoviscoelasticity and so on. Part I presents physical modeling a nd typical numerical analysis results of residual stresses and birefringence in the injection molded center-gated disk. Thermal residual stress was found to be extensional near the center, compressive near the surface and tend to become toward tensional at the surface. A double-hump profile was obtained across the thickness in birefringence distribution: nonzero birefringence is found to be thermally induced, the outer peak is due to the shear flow and subsequent stress relaxation during the filling stage a nd the inner peak is due to the additional shear flow and stress relaxation during the packing stage. Predicted birefringence including both the flow -induced and thermally-induced one becomes quite similar to the experimental one.

• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 2005년도 춘계학술대회 논문집
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• pp.436-441
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• 2005

In this study, precision injection molding analysis for BGA connector fabrication was performed. A BGA connector model with rectangular micro-holes were introduced to investigate the effect of mirco patterns on the injection molding process. Dual domain(2.5D) mesh and full 3D mesh for BGA connector model were prepared to perform precision injection molding analysis. To verify the Present analysis, experiments of injection molding were performed based on the results of the analysis. It was shown that the type of mesh has a significant effect on the flow pattern of BGA connector

• Elastomers and Composites
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• 제39권3호
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• pp.193-208
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• 2004

사출성형된 고분자 블렌드의 형태학적 상구조를 실험 및 이론적인 방법으로 연구하였다. 실험적인 연구로서, 형태학적 상구조에 미치는 사출속도, 사출온도 효과를 조사하였다. 이를 통하여 고분자 블렌드로 제조된 사출성형품에서 두께 위치에 따른 형태학적 상구조 변화를 뚜렷하게 관찰할 수 있었으며, 사출성형품 표면에 분산상이 가늘고 길게 변형되어있는 스킨층, 그안 쪽에 분산상이 다소 크고 변형이 되어있는 서브스킨층 및 사출성형품의 중심에 위치하고 분산상의 변형이 전혀 없는 코어영역이 존재함을 알 수 있었다. 실험적인 연구 결과를 토대로 고분자 블렌드의 사출과정에서 형성되는 형태학적 상구조를 예측하는 계산 알고리듬을 제시하였다. 상업화된 사출성형 해석용 프로그램에서 얻은 유동장 정보와 유동장에서 분산상의 거동에 관한 이론 및 실험식을 조합하여 사출성형된 고분자 블렌드의 형태학적 상구조를 예측할 수 있었다. 제시된 계산 알고리듬으로 사출온도 및 사출속도에 의한 형태학적 상구조의 변화를 잘 예측할 수 있었다.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2006년도 춘계학술대회 논문집
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• pp.357-358
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• 2006

Importance of using an injection molding analysis has been increased. However the application of it has not been increased because the results of analysis do not sometime match to practical molding. Therefore, the difference of flow analysis and practical molding should be decreased. This study presents reasons of the difference for the location of weld-line in the flow analysis and practical molding on automobile bumper molding.

• 한국가시화정보학회지
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• 제9권1호
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• pp.49-54
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• 2011

An investigation has been made of a viscous incompressible flow in a circular cylindrical tank. The flow is driven by the spinning bottom disk of tank together with/without central injection and radial uniform-ejection through the sidewall. Numerical solutions of steady and unsteady flows to 3-dimensional Navier-Stokes equation were obtained for several cases of injection strength. In a moderate flow rate of injection, the mass transfer occurs through the boundary layers but, as the flow rate increases, the inner region far from the container walls takes part in mass transfer.

• Design & Manufacturing
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• 제2권1호
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• pp.39-43
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• 2008

There occur not only many problems in the injection process but also low quality productivity due to the injection conditions of various injection factors. Injection molding process factors such as molding temperature, injection pressure, flow rate and flow velocity, must be controlled properly in filling and packing phases in the injection molding process. In this study, effects of these factors on the injection molding were investigated through the flow analysis for the holding pressure affecting cooling time. Results of this study would be helpful to setting of holding pressure for optimization of forming condition in order to reduce cooling time in injection molding.

• 소성∙가공
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• 제11권5호
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• pp.414-422
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• 2002

Most of numerical analyses for injection molding have been based on the Hele Shaw's approximation: two-dimensional flow analysis. In some cases, that approximation causes significant errors due to loss of geometrical information as well as simplification of the flow characteristics along the thickness direction. The present work covers numerical analyses of injection molding using three-dimensional solid elements. The accuracy of the analysis results has been verified through some numerical examples in comparison with the classical shell-based approach. The Proposed approach is then applied to predict product defects and to improve flow characteristics for a precision electronics part. In addition, design of experiment has been utilized in order to find the optimal process conditions for better product quality.

• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 2002년도 금형가공 심포지엄
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• pp.68-75
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• 2002

Most of numerical analyses for injection molding have been based on the Hele Shaw's approximation: two-dimensional flow analysis. In some cases, that approximation causes significant errors due to loss of geometrical information as well as simplification of the flow characteristics along the thickness direction. The present work covers numerical analyses of injection molding using three-dimensional solid elements. The accuracy of the analysis results has been verified through some numerical examples in comparison with the classical shell-based approach. The proposed approach are then applied to predict product defects and to improve flow characteristics for a precision electronics part. In addition, design of experiment has been utilized in order to find the optimal process conditions for better product quality.

• KSBB Journal
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• 제16권5호
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• pp.459-465
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• 2001

본 연구에서는 생물공정에서 주요 기질로 이용되는 글루코오스와 전분을 온라인 모니터링 하기 이하여 GOD, AMG를 이용한 흐름 주입분석(Flow Injection Analysis : FIA) 기술을 개발하였고, 효소활성 변화를 비교, 고찰하였다. 특히, epoxy 고분자 담체에 고정화된 COD-FIA와 AMG/GOD-FIA 장치의 성능을 조사하였고, FIA의 조작온도, pH, 운반용액의 첨가제, 염 그리고 각종 신진대사물질의 고정화된 GOD, AMG의 활성에 대한 영향을 소형 반응기내 글루코오스와 전분의 농도 변화를 온라인 모니터링하였다. GOD-FIA에 의한 온라인 모니터링 결과는 오프라인 분석과 비교적 잘 일치하였으며, AMG/GOD-FIA에의한 전분 농도의 온라인 모니터링은 단일 효소 반응기를 사용한 경우 두 개의 효소 반응기를 사용한 경우보다 더 효과적임을 알 수 있었다.