• Design & Manufacturing
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• 제13권3호
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• pp.1-11
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• 2019

Recently, studies on the development of flexible electronic devices by combining flexible materials and a conductor have been actively performed as interest in wearable devices. Especially, carbon nanotubes (CNT) or graphene coating have been used to construct a circuit to induce improvement in flexibility and rigidity. Various technologies have been developed in the surface coating of conductive materials, which are key to the manufacture of flexible electronic devices. Surface coating products with 3D coating and micro-patterns have been proposed through electrospinning, electrification, and 3D printing technologies. As a result of this advanced surface coating technology, there is a growing interest in manufacturing gradient conductive surfaces. Gradient surfaces have the advantage that they are adapted to apply a gentle change or to inspect optimum conditions in a particular region by imparting continuously changing properties. In this study, we propose a manufacturing technique to produce a continuous gradient conductive surface by combining a partial stretching of elastomer and a conductive material coating, and introduce experimental results to confirm its performance.

• 한국공작기계학회논문집
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• 제17권6호
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• pp.104-110
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• 2008

A lot of straight bevel gears have been manufactured by the cold forging process in order to improve the productivity and mechanical property of the product. The die for the cold forging of the gear needs high precision and reproducibility. In the study, cold forging die has been modeled by CAD/CAM and manufactured by machining center using ball end mill coated by (Al, Ti)N for heat-treated alloy steel(STD11, HRC 60). Through the measurement of the machined die, satisfactory dimensional accuracy and surface roughness were obtained. In the future, many 3-d cold forging dies will be directly machined instead of electric discharge machining.

• Design & Manufacturing
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• 제13권1호
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• pp.48-54
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• 2019

Analytical and experimental study were carried out in order to achieve simultaneous coating and injection molding of an automotive armrest. A mold was designed to be included one core and two cavities, which were composed of a substrate cavity and a coating cavity. The materials used were PC/ABS for substrate and 2-component Polyurethane for coating. The predicted flow patterns were in good agreement with experimental results in injection molding and in-mold coating. Based on analysis and experiment, it was found that the optimal processing conditions were packing pressure of 90MPa and holding time of 7sec.

• Design & Manufacturing
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• 제13권1호
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• pp.42-47
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• 2019

Nucleate boiling heat transfer is one of the most important phenomenon in the various industries. Especially, critical heat flux (CHF) refers to the upper limit of the pool boiling heat transfer region. Therefore, many researchers have found that CHF can be significantly increased by adding very small amounts of nanoparticles. In this study, the CHF and heat transfer coefficient were tested under the pool boiling state using copper and multi wall carbon nanotube nanoparticles. The results showed that two different types of nanoparticles deposited on the surface of two specimens made of the same material increased the heat flux in the nanoparticles with high conductivity, and there was no difference in the critical heat flux when the same material nanoparticles were deposited on the two different specimen surfaces.

• 한국기계가공학회지
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• 제20권2호
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• pp.120-125
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• 2021

Phylon molds are widely used for injection molding of foams used in shoe outsoles. Injection pylon molds are usually prepared by first casting the aluminum alloy and then applying an anodized coating to improve durability. This study was carried out to examine the durability of aluminum phylon molds. The aluminum materials used in this study were A771, A6061, and AC4C, and their mechanical properties were compared. Specimens for anodic oxidation tests were prepared with coating thicknesses of approximately 10 and 40 ㎛. We tried to select the optimum material and coating thickness suitable for fabricating phylon injection molds. Among the three materials, A6061 exhibited the best tensile, wear, and impact properties. The difference in the wear resistance between the soft- and hard-anodized coatings was insignificant.

• 대한기계학회논문집A
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• 제30권10호
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• pp.1179-1186
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• 2006

This paper was designed to assess the adhesive properties of hard coatings on non-nitrided and nitrided various tool steels. Estimations of adhesion were done to scratch test which is mainly used in hard coating. The critical load$(L_c)$ between coating and substrate is defined through analysis of frictional load vs. normal load curve, signals of acoustic emission and optical observations. Coatings employed in this study are TiN, CrN and TiAlN, tools as substrates are STD11, STD61 and SKH51. It was classified to substrates with/without intermediate nitrided layer and hard coatings on substrate were deposited by arc PVD. Results showed that harder substrates and coatings give higher values of critical loads.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2012년도 춘계학술대회 논문집
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• pp.977-978
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• 2012

• 광학세계
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• 통권136호
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• pp.28-31
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• 2011

2007년에 설립된 엔투에이(대표 김풍전, www.n2a.co.kr)는 'from Nano to Angstrom'의 약자로 이뤄진 N2A라는 회사명에서 알 수 있듯이 초정밀 가공기술을 근간으로 탄탄한 입지를 구축해 나가고 있다. 누구도 흉내 낼 수 없는 초정밀가공기술이라는 강점을 바탕으로 근래에는 광학설계부터 금형, 사출, 코팅, 조립에 이르기까지 광학부품 및 시스템에 필요한 토털솔루션을 완성하고 국내를 넘어서 세계시장 진출을 준비하며 지속적인 성장의 발판을 마련하고 있다.

• 한국기계가공학회지
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• 제9권1호
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• pp.81-86
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• 2010

This paper investigated into process characteristics of AlTiN coated layers for machining to the direction of upper and lower in plastic mold material (KP-4) with the cemented carbide ball endmill with the diameter of 8mm coated AlTiN layers (1~4) step by step using machining center. The material used in experiments was KP-4 that was machined by three types of inclined angles; $15^{\circ}$, $30^{\circ}$ and $45^{\circ}$ As estimated mechanical properties of AlTiN coated layers, it was shown the most result in the condition of three layered coating that the coating that the coating depth, the hardness of the coated layer and the surface roughness of the coated layer were $13{\mu}m$, Hv 3027.3 and $0.042{\mu}m$, respectively. The cutting component was better at the condition of upper direction than that of lower direction in all experimental conditions and indicated to be less which the bigger angle of the material was increased the effective diameter of the tool.

• 소성∙가공
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• 제32권5호
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• pp.247-254
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• 2023

This study conducted the wear tests on bending punches coated with PVD CrN and examined the surface quality of the product formed by each punch in the forming of uncoated TRIP1180 sheets. The study quantitatively estimated the surface quality of the product by measuring the roughness and imaging the product surface. The correlation between the punch wear depth and the product surface roughness was quantitatively analyzed. The results showed that before failure occurs, the product roughness was comparable with that of the as-received, and the product surface was smooth without scratches and defects. However, after failure, the punch wear is caused by fretting wear mechanism, and a punch whose coating is not completely peeled plows the product surface, resulting in severe scratches with grooves and ridges on the product surface. Severe wear on the punch surface caused by fretting wear can rapidly degrade the product surface quality as it is directly affected by the punch surface condition, and the product surface quality accurately reflects the punch wear condition.