• Title/Summary/Keyword: Over-molding

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Evaluation of Physical and Mechanical Properties based on Liquid Composite Molding (액상성형공정별 물리적/기계적 특성 비교 평가)

  • Park, Dong-Cheol;Kim, Tai-Gon;Kim, Seung-Hyeok;Shin, Do-Hoon;Kim, Hyeon-Woo;Han, Joong-won
    • Composites Research
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    • v.31 no.6
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    • pp.304-310
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    • 2018
  • Autoclave process has been remaining as one of the most robust and stable process in fabricating structural composite part of aerospace industry. It has lots of advantages, however exhibits some disadvantages or limitations in capital investment and operation. Recently, there have been various Out-of-Autoclave process being researched and developed to overcome those limitations. In this study, laminate specimens were fabricated using LCM (Liquid Composite Molding) process, regarded as one of potential OoA process. DB (Double bagging), CAPRI (Controlled Atmospheric Pressure Resin Infusion), VAP (Vacuum Assisted Process) and Autoclave process were used for laminate specimens. Void content, Thickness, Tg (Glass Transition Temperature), ILSS (Interlaminar Shear Strength) and Flexural strength properties were evaluated for comparison. It is verified that Autoclave based specimen has uniform thickness distribution, the lowest void content and outstanding mechanical properties. And, CAPRI based specimen exhibits relatively good physical and mechanical properties over DB and VAP based specimen and comparable mechanical properties with autoclave based specimen.

Raising Seeding Status of Onion under Different District in Southern Part of Korea (남부지역에서의 양파 육묘실태)

  • 정동희
    • Korean Journal of Plant Resources
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    • v.9 no.2
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    • pp.113-119
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    • 1996
  • This study inverstigates growing seedling of onion for 91 farmhouses at Muan, Hampyeong and Sinan which are major areas of production from Jan. to Apr., 1994 to enhance the research effect of onion and then the following results are obtained. Over 60% of the farmhouses have cultured onion continuously over 11years. Early mature variety cultured is over 9 varieties and among them Kinkyu variety is cultured most frequently. Late mature variety is over 13 and Changyongdaego, Bonganwhang and Chunjudaego varieties are cultured most. Most of the farmhouses used seeds less than 6 dl at small area less than $40m^2$ and especially in the case of early variety ,they purchased it at seed stores with 15,000-20,000 won/dl and sowed them with broadcasting method. Amount of fertilizer level of onion seed is ranged from nonfertilizer level to $16.8g/m^ and most of the farmhouses employ molding after seeding with straw and compost and they did not use thinning. Irrigation is performed by 1-4 times before sprouting of onion seed and most of the farmhouses transplant long nursery plant over 46 days hand weeding is used.

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Fabrication of micro/nanoscale hierarchical structures and its application (마이크로/나노 계층구조 형성법 및 응용)

  • Jeong, Hoon-Eui;Kwak, Rho-Kyun;Lee, Seung-Seok;Suh, Kahp-Yang
    • Proceedings of the KSME Conference
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    • 2007.05a
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    • pp.426-428
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    • 2007
  • A simple method is presented for fabricating micro/nanoscale combined hierarchical structures using a two-step UV-assisted capillary molding technique. This lithographic method consists of two steps: (i) fabrication of partially cured polymer microstructures using a PDMS mold and (ii) subsequent nanofabrication using a high-resolution polyurethane acrylate (PUA) mold on top of the pre-formed microstructures. Using this technique, various micro/nano hierarchical structures were fabricated with minimum resolution down to 70 nm over a large area with very good reproducibility.

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A Study on the Sliding Wear Characteristicsn of the Die Steel for the Cold Molding (냉간성형용 Die 강의 미끄럼 마멸특성에 관한 연구)

  • 전태옥;박흥식;류경곤
    • Tribology and Lubricants
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    • v.9 no.1
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    • pp.38-44
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    • 1993
  • The present study was undertaken to investigate the dry wear characteristics of die steel STD 11 for cold molding. The wear test was experimentally carried out under different conditions using a wear device, which was made in laboratory, and in which annular surfaces of wear testing specimens wear rubbed in dry sliding condition with varying the sliding speed, contact pressure, and sliding distance. The wear loss by variation of sliding speed was much in 0.3 m/sec and less in higher speed range above its sliding speed according to formation of the boundary lubrication film. The critical sliding speed with maximum value of the specific wear rate switched over to lower speed side according. as contact pressure increased. The critical sliding distance was increased with decrease in oxidation reaction velocity. The depth below subsurface showing maximum hardness (Hv) came out at the position, $60 \mu m$, of the maximum shear stress due to strain hardening.

Robust Design of Warpage in Injection-Molded Parts Using the Response Surface Methodology (반응표면분석법을 이용한 사출성형품의 휨의 강건설계)

  • 박종천;김경모;안흥일
    • Transactions of Materials Processing
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    • v.10 no.6
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    • pp.493-499
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    • 2001
  • An optimal robust design methodology has been developed to minimize warpage in injection-molded pats. The response surface methodology was applied to obtain a functional relationship between design variables and warpage value, and the modified complex method was used as an optimization tool to search for an optimal design solution over prescribed design region. To attain robustness against process variations, Taguchi's SN ratio was introduced as the design metric. The proposed optimal design procedure was applied to an actual part, the Guide-ASF model of a fax machine, and the usefulness of the methodology was shown through the CAE simulation using a commercial injection molding software package.

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The Filling Balance of LDPE/ABS/PA6,6 Resin in Variable-Runner-System (가변러너시스템에서 LDPE/ABS/PA6,6 수지의 충전균형)

  • Park, H.P.;Cha, B.S.;Kang, J.K.;Rhee, B.O.
    • Transactions of Materials Processing
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    • v.15 no.9 s.90
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    • pp.641-647
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    • 2006
  • During the injection molding process an excessive packing can occur in the smaller volume cavity because of volumetric difference of the family-mold. It causes warpage by increased residual stress in the product and flesh by over packing. In this study, we used a variable-runner system for the filling balance of the cavities by changing the cross-sectional area of a runner, and confirmed the filling imbalance by temperature and pressure sensors. We carried out experiments to examine the influence of types of resins such as LDPE/ABS/PA6,6 on the filling balancing of the system, in order to help mold designers, who can easily adopt the variable-runner system to their design. We also examined filling imbalance in the system with CAE analysis.

Analyses on Deformation Patterns Depending on the Injection Process for Rear Lamp Reflectors of Automotive (자동차 리어램프 반사판의 사출공정에 따른 변형 패턴 분석)

  • Choi, Hyun-Jin;Park, Chul-Woo;Choi, Seong-Dae
    • Journal of the Korean Society of Manufacturing Process Engineers
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    • v.9 no.4
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    • pp.32-37
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    • 2010
  • One of the most common engineering processes using plastics is the injection molding. In addition, plastics are utilized over the entire areas in our life including cars and home appliances among others for their characteristics with no deterioration even after a long time, as well as for their light weights in addition to their good durability. This paper aimed to minimize defects through prior analyses on the weld line, air traps, filling time, molding temperature and deformation patterns among others while carrying out interpretations on the cooling, filling and deformation in the injection process using the moldflow for rear lamp reflectors among components for a car in making parts through the coating process after injection.

Fabrication of Polydiacetylene Nanowire Using Nanotransfer Molding

  • Cho, Bo-Ram;Dang, Jeong-M.;Sung, Myung-Mo
    • Proceedings of the Korean Vacuum Society Conference
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    • 2010.08a
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    • pp.282-282
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    • 2010
  • We report a new method of fabrication of polydiacetylene nanowire using liquid bridge-mediated nanotransfer molding (LB-nTM), a direct patterning method for the formation of two- or three-dimensional structures with feature sizes between tens of nanometers and tens of micron over large areas with various materials from a molder to a substrate via a liquid bridge between them. First, we fabricate assembled diacetylene monomer nanowire on the substrate then make it polymerize using 254nm UV-light irradiation. The Polydiacetylene nanowires have been investigated by UV-visible absorption spectroscopy, atomic force microscopy (AFM), and scanning electron microscopy (SEM).

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가스사출성형에서 성형조건에 따른 ABS 성형품의 가스채널의 변화

  • 박태원;한성렬;정영득
    • Proceedings of the Korean Society of Precision Engineering Conference
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    • 2004.05a
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    • pp.221-221
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    • 2004
  • 플라스틱의 사출성형중 용용 수지에 가스를 주입하는 가스사출성형(Gas Assisted Injection Molding GAIM)에 의해 성형품을 만드는 생산방법은 약 30년 전부터 유럽지역을 중심으로 시작되었다 GAIN의 개발 배경은 발포성형을 대체하기 위한 공법으로 개발되었다. 발포성형은 싱크마크(sink mark) 제거, 치수안정성, 강도보강의 목적으로 사용하는 공법이지만, 가스기포가 표면으로 빠져나오고 표면에 가스 기포가 발생하여 외관부품에 부적당하며, 두께가 5-6mm이하의 성형품에는 적용할 수 없고, 성형시간이 긴 문제점을 가지고 있어 이러한 문제를 보강한 공법을 연구할 결과로 GAIM이 탄생하게 되었다.(중략)

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A Study on Improvement of Birefringence Characteristics of Injection-Molded Plastic Parts by Rapid Mold Heating (급속 금형가열에 의한 사출성형품의 복굴절특성 개선에 관한 연구)

  • Park, Keun;Kim, Byung H.
    • Transactions of Materials Processing
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    • v.16 no.4 s.94
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    • pp.229-233
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    • 2007
  • The present work focuses on the prediction of birefringence in injection-molded part and its improvement by rapid mold heating. To calculate birefringence, flow-induced residual stress is computed through a fully three-dimensional injection molding analysis. Then the stress-optical law is applied from which the order of birefringence can be evaluated and visualized. The birefringence patterns are predicted for a rectangular plate with a variation of mold temperature, which shows that the amount of molecular orientation and birefringence level decreases with an increase of mold temperature. The effect of mold temperature on the order of birefringence is also studied for a thin-walled rectangular strip, and the relevant results are compared with experimental measurements. Both predicted and experimental patterns of birefringence are in agreements on the observation that the birefringence level diminishes significantly when the mold temperature is raised over the glass transition temperature.