• 한국분말재료학회지
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• 제6권1호
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• pp.88-95
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• 1999

The purpose of this study is to investigate the manufacturing feasibility of WC-Co milling inserts via Powder Injection Molding (PIM) process. WC-Co is used in a wide variety of cutting tools due to its high hardness, stiffness, compressive strength and wear resistance properties. WC-Co parts for a high stress application were conventionally produced by the press and sinter method, which were Iimited to 2 dimensional shapes. Manufacturing WC-Co parts for a high stress application by PIM implies that tool efficiency can be highly improved due to increased freedom is design. P30 grade WC powder (WC-Co-TiC-TaC system) was mixed with RIST-5B133 binder and injection molded into milling inserts (Taegu Tech. Model WCMX 06T 308). The mean grain size of the powder was about 0.8$\mu$m. Injection molded specimens were debound by solvent extraction and thermal degradation method at various conditions. The specimens were sintered at 140$0^{\circ}C$ for 1 hr in vacuum. Carbon content, weight loss, dimensional change, and macro defects of the specimen were carefully monitored at each stage of the PIM process. PIMed WC-Co milling inserts reached 100% full density after sinteing. Its mechanical properties and micro-structures were comparable with the press and sintered milling insert. Carbon content of the sintered WC-Co insert was mainly determained by the atmosphere of thermal debinding. By controlling powder loading and injection molding condition, dimensional accuracy could be obtained within 0.4%. We confirm that PIM can not only be an alternative manufacturing method for WC-Co parts economically but also provide a design freedom for more effieient cutting tools.

• 한국금형공학회:학술대회논문집
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• 한국금형공학회 2008년도 하계 학술대회
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• pp.69-73
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• 2008

본 연구에서는 고분자 플라스틱 부품의 친환경 외장성형공법인 Insert Film 사출성형공법중 첫 번째 공정인 진공성형공정에서 진공금형의 표면온도 균일화 기술에 대해 연구를 수행하였다. 진공금형의 온도분포 균일화를 위한 금형설계 및 설계된 금형에 대한 온도분포 평가를 위한 ANSYS를 이용한 유한요소열해석을 수행하였으며, 이때 정상상태 및 과도상태를 함께 평가하였다. 설계 결과를 바탕으로 금형을 제작하였으며, 생산성을 고려하여 4캐비티로 제작된 금형에 대해 금형표면의 온도분포 평가실험을 수행하였다. 또한 금형내 캐비티 온도센서 및 제어시스템을 설치하여 진공금형표면 온도분포가 항상 일정하게 유지될 수 있도록 금형시스템을 개발하였다. 결과적으로 일정한 온도범위의 금형표면온도제어가 가능하였다.

• 한국항공우주학회지
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• 제49권2호
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• pp.139-146
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• 2021

하이브리드 로켓 연소에서 산화제 스월 분사는 회전방향 속도성분이 경계층 유동에 영향을 미쳐 연소안정화에 기여한다. 그러나 스월 강도가 증가할수록 연소성능을 과도하게 변화시키는 문제점이 나타난다. 따라서 참고문헌[7]의 삽입연료와 함께 사용하여 연소성능 변화를 최소화 하면서 연소불안정 억제를 시도하였다. 이를 위해, 일련의 실험을 계획하여 스월 강도와 삽입연료 위치를 변화하며 연소불안정의 발생과 연소성능 변화를 관찰하였다. 실험결과, 스월 각 6°, 삽입연료 위치 310 mm 조합에서 연소불안정이 억제되었으며 연소압력, O/F 비 그리고 연료 후퇴율 등의 변화가 최소인 것으로 확인하였다. 또한 고주파수 대역의 압력진동(p')와 열방출진동(q')의 위상차가 π/2로 음의 결합을 형성하도록 연소조건을 유지하는 것이 저주파수 연소불안정 발생을 억제하는 필요충분조건임을 재확인하였다.

• 한국공작기계학회논문집
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• 제11권6호
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• pp.68-74
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• 2002

This research covers the development of axi-symmetric plastic elements for injection molding with insert steel such as high stiffness Sabot. The functional requirements of sabot are concentricity and fracture resistance about vertical and horizontal forces. For these, an analysis of characteristics of PEI(polyetherimide) polymer is performed by standard test specimen with accordance of ASTM test guidance. Moldflow analysis and simulation of injection molding process are carried out in order not only to estimate of the warpage but also to predict the characteristics of residual stresses which both product and structure of mold may have. A new vertical side injection machine and transverse mold have been constructed. Results of the measuring concentricity and fracture test after molding of sabot are satisfied to design specification over Cp $ratio{\geq}1.33$. Finally, this technique needs more research application to others axi-symmetric elements having different radius with insert steel md structure analysis from now on.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2008년도 춘계학술대회 논문집
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• pp.819-820
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• 2008

• 소성∙가공
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• 제20권1호
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• pp.64-72
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• 2011

In this study, we have investigated bonding of metal and plastic parts with single planar interface. This is facilitated by surface processing of aluminum sheet, which consists of slitting and punching, followed by insert-molding of polybuthylelne terephthalate(PBT). An injection mold has been built to fabricate specimen. After processing of the specimen, tensile and bending shear adhesion tests have been fulfilled according to KS M3734 and KS M3723, respectively. We also have conducted simulation of tensile and bending shear adhesion tests. Based on the tests results, the proposed bonding method outperforms existing methods based on adhesion.

• 한국정밀공학회지
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• 제21권12호
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• pp.13-20
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• 2004

Manufacturing process for the microfluidic device can include such sequential steps as master fabrication, electroforming, and injection molding. The laser ablation using masks has been applied to the fabrication of channels in microfluidic devices. In this study, manufacturing of polymer master and mold insert for micro injection molding was investigated. Ablation of PET (polyethylene terephthalate) by the excimer laser radiation could be used successfully to make three dimensional master fur nickel mold insert. The mechanism fur ablative decomposition of PET with KrF excimer laser $({\lambda}: 248 nm, pulse duration: 5 ns)$ was explained by photochemical process, while ablation mechanism of PMMA (polymethyl methacrylate) is dominated by photothermal process, the .eaction between PC (polycarbonate) and KrF excimer laser beam generate too much su.face debris. Thus, PET was adopted in polymer master for nickel mold insert. Nickel electroforming using laser ablated PET master was preferable for replication method. Finally, it was shown that excimer laser ablation can substitute for X-ray lithography of LIGA process in microstructuring.

• 소성∙가공
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• 제21권1호
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• pp.30-35
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• 2012

FIM(Film Insert Molding) is an innovative method of producing decorated parts for a wide range of products. Because it requires fewer steps when compared to conventional production methods, the time and cost of manufacturing high quality components can be reduced considerably. In this paper, the effects of processing conditions on the warpage of film-insert molded plate were investigated by using a design of experiments. The dominant factors affecting warpage were mold temperature and holding pressure. Warpage increased with the temperature difference between stationary mold and fixed one. Even when the mold temperature difference was zero, the plate with a film was bent after ejection such that the film side protruded. As holding pressure increased, warpage decreased significantly. In addition warpage increased with time increment for the film-insert molded plates.

• 한국생산제조학회지
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• 제21권5호
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• pp.790-796
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• 2012

Chip curling occurred during cutting process for difficult-to-cut material detracts product qualities and productivity. Among of method preventing the phenomenon, high pressure injecting cutting oil is an alterative. In this study, the optimal nozzle was designed by CFD method and it was conducted to analyse on the effect of high pressure injection on chip shape generated during cutting process and wear of insert by experimental method. As the result, it could be confirmed that high pressure injection is favorable for preventing chip curling and insert from wearing.

• 한국기계가공학회지
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• 제11권6호
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• pp.55-61
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• 2012

In this study, it was grasped to the flow characteristics of injection nozzle installed in high pressure holder for improving productivity. Chip curling occurred during cutting process for difficult-to-cut material detracts product qualities and productivity. Among of method preventing the phenomenon, high pressure injecting cutting oil is an alterative. In this study, the optimal nozzle was designed by CFD method and it was conducted to analyse on the effect of high pressure injection on chip shape generated during cutting process and wear of insert by experimental method. As the result, it could be confirmed that high pressure injection is favorable for preventing chip curling and insert from wearing.