• 한국주조공학회지
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• 제13권1호
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• pp.42-49
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• 1993

Conventional manufacturing process for cast iron-babbitt metal composite is complicate and bimetallic bonding by centrifugal casting is also difficult because their melting point is largely different and nonmetallic inclusion exists on outer shell. This study is aiming to simplify multistage process by adding Cu-powder as insert metals during cast iron solidification. The variables on fabrication of composite pipe are mold rotating speed and inner surface temperature of outer metal. The optimum temperature range for fusion bonding between cast iron and Cu-layer was $1100^{\circ}C-1140^{\circ}C$ in case of mold rotating speed was 700rpm. When the inner surface of Cu-layer was at $900^{\circ}C$, the value of interfacial hardness between Cu-layer and babbitt metal were higher than Cu-matrix by forming diffusion layer, interfacial products between Cu-layer and babbitt metal are proved to be $Cu_6Sn_5({\eta})$by XRD.

• Design & Manufacturing
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• 제17권1호
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• pp.40-47
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• 2023

Macular degeneration and glaucoma are representative age-related retinal diseases that rank second and third in the prevalence of retinal diseases, and are a kind of degenerative neurological disease. Irreversible visual acuity and visual field damage may occur, and the number of patients is rapidly increasing as the population ages. Since this retinal disease is a chronic disease, continuous drug treatment is required. There are various drug delivery methods for treatment, but direct injection of the drug into the intravitreal is the most effective for continuous delivery of the drug over a long period of time. In order to solidify Dexamethasone, a retinal disease treatment, and insert it into the primary intravitreal, it is important to develop a technology to miniaturize the treatment and an applicator to deliver the treatment. In this study, a mold technology was developed to integrate the cannula and hub, which are one part of applicator. In addition, surface treatment was performed on the outside of the cannula to improve the bonding strength between the cannula and the hub, and the bonding strength according to each condition was analyzed through a tensile test.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2005년도 추계학술대회 논문집
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• pp.111-114
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• 2005

Experimental and numerical studies were carried out in order to investigate the processability and the transcriptability of the injection molding of micro structures. For this purpose, we designed a mold insert having micro rib patterns on a relatively thick base part. Mold insert has a base of 2mm thickness, and has nine micro ribs on that base plate. Width and height of the rib are $300{\mu}m\;and\;1200{\mu}m$, respectively. We found a phenomenon similar to 'race tracking', due to 'hesitation' in the micro ribs. As the melt flows, it starts to cool down and melt front located in the ribs near the gate cannot penetrate further because the flow resistance is large in that almost frozen portion. When the base is totally filled, the melt front away from the gate is not frozen yet. Therefore, it flows back to the gate direction through the ribs. Consequently, transcriptability of the rib far from the gate is better. We also verified this phenomenon via numerical simulation. We further investigated the effects of processing conditions, such as flow rate, packing time, packing pressure, wall temperature and melt temperature, on the transcriptability. The most dominant factor that affects the flow pattern and the transcriptability of the micro rib is flow rate. High flow rate and high melt temperature enhance the transcriptability of micro rib structure. High packing time and high packing pressure result in insignificant dimensional variations of the rib. Numerical simulation also confirms that low flow rate causes a short shot of micro ribs and high wall temperature helps the filling of the micro ribs.

• 한국산학기술학회논문지
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• 제15권1호
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• pp.21-26
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• 2014

치과에서 사용되는 구강 치료용 요오드 용기는 개폐 시 용기의 캡에 부착되어 있는 칼날에 의해 치료용 실은 절단이 된다. 금속의 칼날은 요오드 용액과 반응하여 단기간에 부식이 되는 문제로 인해 환자의 위생에도 영향을 준다. 이러한 문제를 해결하기 위해 최근 세라믹 칼날로 대체되어진 제품들도 개발되어 생산되는데, 이때 세라믹 칼날은 수작업과 기계가공을 통해 만들어 진다. 본 연구에서는 세라믹 칼날을 분말사출성형공정으로 대량 생산할 수 있도록 20Cavity의 균일 충전을 위한 유동 시스템을 제안하였다. Moldflow를 이용하여 20cavity 유동성에 대한 시뮬레이션을 진행하였고, 금형제작과 수정을 통해 금형을 완성하였다. 사출성형 후 탈지와 소결공정을 통해 완성하고, 금형에 세라믹 칼날을 인서트 사출하여 캡 제품을 완성하였다. 본 연구를 통해 유효한 절단 성능을 갖는 세라믹칼날 대량생산 가능성을 검증하였다.

• Composites Research
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• 제31권4호
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• pp.139-144
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• 2018

장섬유강화 복합재료는 기존의 연속섬유강화 복합재료에 비해 우수한 생산 효율성과 복잡한 형상의 성형성에 대해 장점을 가지고 있다. 하지만 지나치게 복잡한 복합재료 형상을 제작하거나 서로 다른 재료로 제작된 부품들을 조립/체결해야 하는 경우 다양한 접합 방법들이 필요하다. 일반적으로 LFPS(Long Fiber Prepreg Sheet)는 성형 후 탈형을 쉽게 하기 위해 LFPS안에 이형제가 포함되어 있다. 그러므로 적절한 접합 강도를 위해 접착법과 더불어 기계적인 체결이 요구된다. 본 연구에서 열성형 공정을 통해 LFPS를 경화하고 스테인레스 강 인서트를 접착하는 동시경화 접착을 위한 스테인레스 강 인서트를 제안하였다. 성형공정 동안 펼쳐지는 스테인레스 강 인서트의 날개는 접착력과 기계적인 고정(Mechanical wedging)의 효과를 유발하여 인발력에 저항할 수 있는 갈고리 역할을 한다. 복합재료에 삽입된 인서트 날개들의 펼쳐진 상태를 확인하기 위해 소각 방법을 사용하였다. 그리고 접합 강도를 정량적으로 평가하기 위해 인발시험(Pull-out test)을 수행하였다. 이러한 실험들을 통해 가장 적절한 접합 강도를 보장하는 조건을 도출하였다.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2004년도 추계학술대회 논문집
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• pp.237-240
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• 2004

Indexable end mills, which consist of inserts and cutter body, have been widely used in roughing of parts in the mold industry. The geometry and distribution of inserts on cutter body are determined by application. This paper proposes analytical cutting force model for indexable flat end-milling process. Developed cutting force model uses the cutting-condition-independent cutting force coefficients and considers runout, cutter deflection and size effect for the accurate cutting force prediction. Unlike solid type endmill, the tool geometry of indexable endmill is variable according to the axial position due to the geometry and distribution of inserts on the cutter body. Thus, adaptive algorithm that calculates tool geometry data at arbitrary axial position was developed. Then number of flute, angular position of flute, and uncutchip thickness are calculated. Finally, presented model was validated through some experiments with aluminum workpiece.

• 한국주조공학회지
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• 제20권3호
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• pp.188-196
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• 2000

A vacuum casting was proposed as a new fabrication method of Si wafer for solar cell substrate. It was tried to fabricate a Si plate with good properties and to reduce the production cost by direct vacuum casting. By $5{\sim}10$ cmHg of pressure difference Si plate with $50{\times}46{\times}1.5\;mm^3$ was fabricated. For the preventing of the reaction between graphite mold and Si melt, BN powder coating or BN insert were used. The Si wafer was poly crystalline with 100 ${\mu}m{\sim}1$ mm order of grain size. And there were some twins and dislocations in the grains.

• Design & Manufacturing
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• 제14권4호
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• pp.71-77
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• 2020

Various manufacturing technologies, including over-molding and insert-injection molding, are used to produce hybrid plastics and metals. However, there are disadvantages to these technologies, as they require several steps in manufacturing and are limited to what can be reasonably achieved within the complexities of part geometry. This study aims to determine a practical approach for producing metal/plastic hybrid components by combining plastic injection molding and metal die casting to create a new hybrid metal/plastic molding process. The integrated metal/plastic hybrid injection molding process developed in this study uses the proven method of multi-component technology as a basis to combine plastic injection molding with metal die casting into one integrated process. In this study, the electrical conductivity and ampacity were verified to qualify the new process for the production of parts used in electronic devices. The electrical conductivity was measured, contacting both sides of the test sample with constant pressure, and the resistivity was measured using a micro ohmmeter. Also, the specific conductivity was subsequently calculated from the resistivity and contact surface of the conductor path. The ampacity defines the maximum amount of current a conductive path can carry before sustaining immediate or progressive deterioration. The manufactured hybrid multi-components were loaded with increasing currents, while the temperature was recorded with an infrared camera. To compare the measured infrared images, an electro-thermal simulation was conducted using commercial CAE software to predict the maximum temperature of the power loaded parts. Overall, during the injection molding process, it was demonstrated that multifunctional parts can be produced for electric and electronic applications.

• 한국기계가공학회지
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• 제14권6호
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• pp.7-13
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• 2015

The production processes were reviewed through the injection analysis of the shift lever as a core component of an auto lever installed in the automatic transmission of cars. The injection analysis was carried out for the shift lever and rod among the components in a shift lever module. The shift lever and rod are designed for injection molding with the insertion of a tube, a pin cable plate, and a steel rod for securing the strength of the product. The charging time, failure of injection molding, weld line, air trap, and deformation were reviewed according to this insert. Analyses on various gate positions were carried out for reviewing the cultivation and deformation of fiber around major components, such as the generation section of manipulation feeling and assembly section, so that optimal gate conditions might be reviewed and reflected in the mold design. Finally, we plan to compare the analysis results with the production of trial products.

• 한국소음진동공학회논문집
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• 제22권4호
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• pp.335-343
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• 2012

As a matter of fact, it has been not allowed to modify the shape of a vehicle body skeleton since the technical definition for the structure was fixed and the corresponding molds were developed. By the way, if it is available to apply an alternative to reinforce the skeleton without changing its mold, it must be much flexible to improve the performance qualities relevant to not only NVH(noise, vibration and harshness) but also crash and durability. Recently, a solution of so-called composite body becomes available for the need. We present a design method to insert the composite body inside a vehicle body skeleton in order to improve a structure-borne noise at the idle condition. The algorithms, topology optimization and design sensitivity analysis, are applied to mainly search the sensitive structural sections in the body skeleton and to extract the target stiffness of the sections. Inserting the composite bodies into the sensitive portions, it is predicted to achieve the countermeasures which can compromize the design availability in terms of the idle noise and weight. According to the validation result with test vehicles, the concerned noise transfer function is reduced and the idle booming noise is resultantly improved.