• 구강회복응용과학지
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• 제17권3호
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• pp.199-204
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• 2001

This study was to investigate the reused possibility of zirconia reinforced glass-ceramic(IPS Empress Cosmo ceramic) with sprue button in the flexure strength and fracture toughness. 40 disk-shaped ceramic specimens (20 specimens: as-pressed material; 20 specimens: reused material) with approximately 1.7 mm thickness and 15 mm diameter were prepared by "lost wax" technique. The remnants(sprue buttons) were used for repressing. The surface treatments for the discs were gradually abraded with 320, 800, 1200, and 2000 grit SiC sandpaper. The specimens were evaluated their flexure strength with the biaxial flexure jig(ball-on-three balls) and their fracture toughness with Vickers Indentation-microfracture test. The Weibull moduli were calculated for biaxial flexural strength. The mean flexure strength and fracture toughness of each group were $122.2{\pm}18.3MPa$, $1.00{\pm}0.09MPa{\cdot}m^{0.5}$ (as-pressed ceramics), and $122.2{\pm}20.3MPa$, $1.01{\pm}0.10MPa{\cdot}m^{0.5}$ (reused ceramics). There were no significant differences in the strength and the fracture toughness between the as-pressed and the reused IPS Empress Cosmo ceramic (P>0.05). This implied zirconia reinforced glass-ceramic(IPS Empress Cosmo ceramic) could be used one more time by reusing of sprue button in the flexure strength and fracture toughness.

• 대한치과보철학회지
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• 제35권1호
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• pp.130-143
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• 1997

A heat-pressed technique(IPS-Empress, Ivoclar) has been described to construct single unit crown, inlay/onlay and veneers using a partially pre-cerammed and pre-colored glass-leucite ingot that has the greateast strength by the combination of heat-pressed procedure through the smalldiameter sprue and heat treatment procedure. The purpose of this study was to evaluate the flexure strength of a heat-pressed ceramic material(IPS-Empress) without simulated firing treatments according to pontic designs. Two groups of 9 disks(1.4mm thick, 14mm in diameter) each using two types of sprues with different diameters($({\Phi}2.8\;,{\Phi}1.8)$) and numbers were prepared. The specimens were mounted in the testing jig. The flexural strengths were determined, by means of the bi-axial bending test, by loading the center of disk to failure using a universal testing machine(Zwick 145141, Zwick, Germany) at a cross-head speed of 1.0 mm/min. The means flexural strength value of one group using a sprue with ${\Phi}2.8$ was $140.4{\pm}8.0Mpa$. That of the other group using two sprues with ${\Phi}1.8$ was $151.8{\pm}10.3Mpa$. After analysis, results showed that there was a statistical difference between groups(t=2.33m p<0.05). No clnical implications were drawn from these data because of absence of simulated firing treatment.

• 한국결정성장학회지
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• 제22권2호
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• pp.105-113
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• 2012

정밀주조기술은 수공예에 의한 일품장신구가 규격화, 표준화된 제품으로 대량 생산될 수 있는 기틀을 만들어 주었고 또한 생산라인의 시스템 개선으로 업무의 분업화와 장비의 첨단화로 명실상부한 장신구가 산업으로서의 면모를 갖추는데 지대한 기여를 하였다. 본 연구자는 주조장비가 국내 도입된 이래 약 30여 년 동안 주조장비의 고급화와 업그레이드에 따른 제품의 질이 향상되었다고 볼 수 있으나 주조장비가 100 % 해결해 줄 수 없는 생산 프로세스를 직시하면서 정밀주조 과정에서 매우 중요하다고 판단되는 왁스트리(Wax Tree)공정 시 수행되는 장신구 사출물과 금속이 용해되어 흘러 들어가는 스프루(Sprue)의 연결은 여전히 수작업에 의해 진행이 되고 있고 이 과정에서 원하는 결과물이 나오는데 많은 영향을 미칠 수 있다는 문제점을 실험데이터를 바탕으로 하여 좀더 완벽한 정밀주조의 프로세스를 수행하기 위한 방안 제시를 하고자 한다.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2011년도 춘계학술대회 논문집
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• pp.1349-1350
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• 2011

• 실천공학교육논문지
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• 제9권2호
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• pp.119-124
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• 2017

사출성형 시 유압실린더의 힘으로 스크류가 앞으로 전진하는 동안, 금형의 러너시스템은 성형품 형상의 캐비티 내를 충진시키는 유로로 용융된 수지의 충진, 패킹과정에 관계되며, 이는 스프루(sprue), 러너(runner), 게이트(gate)에 의해서 성형품의 외관, 수지의 물성, 치수 정밀도 및 성형 사이클 등에 큰 영향을 준다. 러너, 게이트 설계가 잘못된 피드시스템은 다양한 성형불량을 일으키므로 이를 방지할 수 있는 최적의 러너밸런스를 유지하는 것이 중요하다. 사출금형을 제작하는 업체에서 응용할 수 있는 실무적인 금형기술 지식을 향상시키기 위해서 기술적인 애로분야에 대한 기술지도를 바탕으로 금형기술 과정의 훈련모델을 제시한다.

• 한국생산제조학회지
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• 제22권2호
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• pp.248-255
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• 2013

The objective of this study is to optimize the Metal Injection Molding(MIM) process with design of experiments(DOE) and numerical analysis. To derive the optimal process condition, experiment or numerical analysis was performed under various process conditions. To analyze the interaction among influential factors contributing to the temperature at flow front and response surface in MIM, both central point and axial point were added to the full factorial design with 2 levels and 5 factors and then their impacts on response variable in 43 experimental conditions were analyzed and the significance was evaluated. As a result, sprue, runner, and gate were completely filled in about 0.247 seconds after injection, the front part of the green body was filled in about 0.3344 seconds, the green body except gate, etc changed to almost solid state in about 3.29 seconds, the Packinging pressure was completed in about 6.29 seconds, and the green body inside and outside and sprue, etc became solid in 13.2 seconds. The impact of individual or reciprocal action of factors on the temperature at flow front was analyzed through regular probability, test statistics, main effect, and interaction effect. As a result, of a total of 31 combinations of factors, 9 unit factors and reciprocal actions were significant, and the screening was also possible. A proper regression equation was drawn with regression analysis and response surface design on the response variable of temperature at flow front, and the applicability could be verified.

• 한국결정성장학회지
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• 제32권1호
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• pp.25-32
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• 2022

인베스트먼트 주조는 정밀기기, 의료분야, 액세서리 등의 제조에 일반적으로 사용되는 생산방식으로 장비의 현대화와 고품질의 재료를 통해 발전을 거듭해 왔으며 그 활용 범위가 확대되고 있다. 본 연구의 목적은 인베스트먼트 주조 공정의 핵심 요소인 금형 온도의 구조적 개선 및 표준화를 도출하여 불량률을 최소화하여 경제성과 생산성을 향상시키는 것이다. 연구의 범위는 소형탕도의 구조와 원리를 이해하기에 적합한 Jewelry 제조 주조 공정에 국한되어 있으며 연구 재료로 soft Wax, 석고 분말 및 14 K Gold를 사용하여 실험적 연구를 수행했다. 그 결과 Alloy 14 k의 주물 패턴에 가장 적합한 주물 표준 온도는 980℃ 플라스크 온도 550℃에서 가장 낮은 난류로 좋은 제품을 생산할 수 있었다. 본 연구의 향후 과제로 소형탕도의 구조 및 표준온도를 데이터를 분석하고, 현장의 생산 불량을 감소시키고 우수한 인베스트먼트 주조 공법의 경쟁력 확보를 위한 데이터를 제공하기 위한 세부 연구가 필요하다.

• 한국주조공학회지
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• 제24권4호
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• pp.217-224
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• 2004

The effect of casting variable on the fluidity of high silicon, especially hypereutectic, heat-resistant ductile cast iron melt was investigated. When pouring temperature and silicon content were constant, that was increased with carbon content. When the pouring temperature and carbon content were constant, that also increased with the silicon content. Even though these results were thought to be caused by the high heat of fusion evolved during the crystallization of proeutectic graphite nodules, further research seemed to be needed. The fluidity for taller sprue was higher than that for smaller one.

• International Journal of Precision Engineering and Manufacturing
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• 제4권5호
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• pp.34-40
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• 2003

This paper presents the inertial force problem of ultrahigh-speed injection molding machine using linear motors, and presents its solutions. To make very thin products by injection molding, very high injection speed is required, and linear motors are used for this purpose. However, direct drive by linear motors may cause brief nozzle separation from the sprue bushing because of the inertia force which is as large as the total output thrust of the linear motors, and this momentary separation can cause molten plastic to leak. In this paper, two solutions are proposed for this inertia force problem. One is the mechanical cancellation of the inertia force, and the other is to increase the nozzle contact force. With the latter solution, the stationary platen bending worsens, so a new nozzle contact mechanism is also proposed, which can prevent the stationary platen bending.

• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 2004년도 춘계학술대회 논문집
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• pp.101-104
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• 2004

The application of rubber produt is a quite extensive field and has several problems in point of mass-production. The inhibitive factors at the general rubber mold are occurrence of flash, loss of raw material by curing for sprue and runner, environmental pollution by scrap junked after extraction of product and the unavailable mold structure for automation. The existence of flash at the rubber mold requires extra-process for removing or finishing it. As the reason, we can't help avoiding deterioration of quality and rising of cost. Hence we promptly need to research fur the efficient structure of mold and the preventive transforming technique of the flash without any loss of raw material in advance. This monograph is a study for Wasteless rubber mold that give us a solution for several problems happened at the general rubber mold.