• Title/Summary/Keyword: Mold manufacturing

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A Convergent Study on Impact Analysis due to Existence or Non-Existence of Smart-phone Case (스마트폰 케이스의 유무에 따른 충격해석에 관한 융합 연구)

  • Choi, Kye-Kwang;Cho, Jae-Ung
    • Journal of the Korea Convergence Society
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    • v.11 no.10
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    • pp.225-229
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    • 2020
  • In this study, the deformation and stress on each model was analyzed and the strength was compared with each other when the impacts on a total of four smart phone models was given. Models B and D with cases can be seen to have less deformation and stress than models A and C without cases. The models including the case have higher masses than the models without the case. So, the deformation and stress can be reduced by absorbing the impact force. In addition, the masses of models C and D are smaller than models A and B, but the stresses and deformations are seen to be smaller. If a case specialized for edge protection is chosen and designed when manufacturing a smart-phone in order to absorb the shock while weighing less, it is thought to improve the strength of the smart-phone and increase the durability. And it is seen that this study is adequate at the efficient design with durability of smart phone case practically and the aesthetic convergence of smart phone.

Analysis of Flexural Strength of Seedling Pots Made by a Pulp-Molding Machine under Different Water Contents (펄프 몰드식 육묘포트의 성형조건 및 수분 흡습에 따른 굴곡 하중 특성 분석)

  • Song, D.B.;Jeong, J.W.;Kim, C.H.;Huh, M.R.
    • Journal of Korea Technical Association of The Pulp and Paper Industry
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    • v.41 no.4
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    • pp.43-51
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    • 2009
  • Paper mill sludges are discharged around 870,000 M/T annually. Only 30% of the paper mill sludge have been recycled and the rest has been disposed by land fill, incineration, ocean abandonment and other ways. Because of overall prohibition of sludge disposal by London Dumping Convention in 2012, a urgent counter measure for paper mill sludge must be provided. In this paper, some basic experiments were carried out to develop a tray cell pot using paper mill sludge for increasing the recycling potential of the wasted sludge. To establish the manufacturing parameters, the tray cell pots were made with three types of materials including virgin pulp, old news paper and corrugated board mixed in a blend tank of a molding machine. The bending force and moisture content of the produced tray cell pots was measured to confirm the application capability. The tray cell pot could be manufactured under the condition of over 20% of virgin pulp, 40% of old news paper added. However, the corrugated board could not be used because of the glutinous substance included. The produced tray cell pot absorbed water very easily and the bending force decreased rapidly. The waterproof material must be used to applicate the produced tray cell pot in plant growing fields.

Effect of Casting Thickness and Plunger Velocity on Porosity in Al Plate Diecasting (Al 박육 다이캐스팅 주물에서 기포결함에 미치는 주물두께, 사출속도의 영향)

  • Kang, Ho-Jeong;Park, Jin-Young;Kim, Eok-Soo;Cho, Kyung-Mox;Park, Ik-Min
    • Journal of Korea Foundry Society
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    • v.35 no.4
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    • pp.80-87
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    • 2015
  • The Al die casting process has been widely used in the manufacturing of automotive parts when the process requires near-net shape casting and a high productive rate. However, porosity arises in the casting process, and this hampers the wider use of this method for the creation of high-durability automotive components. The porosity can be controlled by the shot condition, but, it is critical to set the shot condition in the sleeve, and it remains difficult to optimize the shot condition to avoid air entrapment efficiently. In this study, the 4.5 mm, 2.0 mm plate die castings were fabricated under various shot conditions, such as plunger velocities of 0.7 m/s ~ 3.0 m/s and fast shot set points of the cavity of -25%, 0%, 25%, and 50%. The mold filling behavior of Al melts in the cavity was analyzed by a numerical method. Also, according to the shot conditions, the results of numerical analyses were compared to those of die-casting experiments. The porosity levels of the plate castings were analyzed by X-ray CT images and by density and microstructural analyses. The effects of the porosity on the mechanical properties were analyzed by tensile tests and hardness tests. The simulation results are in good general agreements with the die-casting experimental results. When plunger velocity and fast shot set point are 1.0 m/s and cavity 25% position, castings had optimum condition for good mechanical properties and a low level of porosity.

A Study on the Effects of Flow Adaptive Gating System and Ceramic Filter on Flow Stability (흐름 적응 탕구계와 필터가 유동 안정성에 미치는 영향 연구)

  • Hwang, Ho-Young;Yin, Song;Nam, Cheol-Hee
    • Journal of Korea Foundry Society
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    • v.37 no.3
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    • pp.71-77
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    • 2017
  • Casting defects produced during the casting process seriously affect the mechanical properties of the resulting products, reduce the performance capabilities of the product, and also result in economic losses. Therefore, this paper mainly investigates the causes of defects and methods by which to reduce these defects stemming from molten metal flows in a runner system of the type widely used in the sand mold casting process. The flow characteristics of a molten alloy are difficult to observe during the actual casting process. For this reason, a water model was used to observe the flow in the casting process, and the flow in each case was recorded using high-speed cameras as part of the experimental process of this study. Several repetitive experiments were performed to improve the accuracy of the experimental results. The traditional casting system was modified according to the design rules proposed by Campbell, and the system was termed flow-adaptive gating system with a water model. Comparing the flow characteristics of traditional and adaptive gating systems with a water model shows that the bubbles in the water in the latter case are reduced more significantly than in the former case. A ceramic filter system was adapted to the flow-adaptive gating system to minimize the instability of the flow during filling, which occurs as the fluid velocity in the runner increases. In additional, the flow behavior with and without the filter system were compared. The water model system in this work was shown to be able to verify that the adaptation of the filter system brings improvements by stabilizing the flow and reducing the amount of bubbles in the runner system. Moreover, using the flow-adaptive runner system with the filter system leads to considerably stable flows in the runner system.

High-accuracy and High-speed Groove Die Set (고정도.고속 Groove Die Set)

  • Kim, Gun-Hoi
    • Transactions of the Korean Society of Machine Tool Engineers
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    • v.17 no.1
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    • pp.7-15
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    • 2008
  • Currently existing high-accuracy and high-speed die sets used in reciprocal press create scratches at the surface of guide posts, steel balls, and bushes due to vertical movement of balls with point-contacts between inner surface of bushes and guide posts. Consequently, accuracy of the die set and the life span of the metal mold are reduced. However, those scratches could reduce the pre-load of the steel ball. This research designed and developed a groove-type die set which improves life span of the die set by eliminating point-contacts of steel balls with guide posts. The guide post consisted of a steel-ball retainer, a steel-ball retainer stopper, a guide bush, a guide pin, a snap ring, and a spring. The steel-ball retainer has 72 holes with 8 columns of 9 holes in each column. The inner surface of the guide bush was grinded(surface roughness: $Ra\;\\;0.2{\mu}m$, accuracy: $0\;{\sim}\;-0.002mm$) after NC turning and heat treatment. Also, a line of small intermediate pocket was processed inside of the guide bush for lubrication and elimination of foreign materials. Guide grooves of steel balls were processed using a wire EDM(Electrical Discharge Machining) after heat treatment. With such a design of the guide post stated above, loads against steel balls could be dispersed greatly by the line contacts through the guide groove between the guide post and the guide bush, and the life span of the guide post could be expanded semi-permanently.

Development of Combined Sheet Metal Forming and Plate Forging of a Metal Seal Part of Hub Bearing for an Automobile (자동차 허브 베어링용 씰 금속부품의 판재성형 및 판단조의 복합성형 공정 개발)

  • Park, K.G.;Moon, H.K.;Oh, S.K.;Joun, M.S.
    • Transactions of Materials Processing
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    • v.29 no.4
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    • pp.194-202
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    • 2020
  • In this paper, experimental and numerical study on a combined sheet metal forming and plate forging of a seal part of a passenger car's hub bearing is conducted to develop the new process of which target is to remove machining process by plate forging and to achieve near-net shape manufacturing. The previous process of a sheet metal forming inevitably needed a machining process for making stepped sheet after conventional sheet metal forming in a progressive way. The stepped sheet is intended to be formed by plate forging in this study. Through the systematic way of developing the combined forming process using solid elements based-elastoplastic finite element method (FEM), several conceptual designs are made and an optimized process design in terms of geometric dimensioning and tolerance of straightness of the thin part is found, which is exposed to bending in metal forming of axisymmetric part. The predicted straightness measured by the slope angle of the tilted thin region is compared with the experimental straightness, showing that they are in a good agreement with each other. Through this study, a systematic approach to optimal process design, based on elastoplastic FEM with solid elements, is established, which will contribute to innovating the conventional small-scaled sheet metal forming processes which can be dealt with by solid elements.

Finite Element Analysis of Powder Injection Molding Filling Process Including Yield Stress and Slip Phenomena (항복응력과 미끄럼현상을 고려한 분말사출성형 충전공정의 유한요소해석)

  • 박주배;권태헌
    • Transactions of the Korean Society of Mechanical Engineers
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    • v.17 no.6
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    • pp.1465-1477
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    • 1993
  • Powder Injection Molding(PM) is an advanced and complicated technology for manufacturing ceramic or metal products making use of a conventional injection molding process, which is generally used for plastic products. Among many technologies involved in the successful PIM, injection molding process is one of the key steps to form a desired shape out of powder/binder mixtures. Thus, it is of great importance to have a numerical tool to predict the powder injection molding filling process. In this regard, a finite element analysis system has been developed for numerical simulations of filling process of powder injection molding. Powder/polymer mixtures during the filling pro cess of injection molding can be rheologically characterized as Non-Newtonian fluids with a so called yield phenomena and have a peculiar feature of apparent slip phenomena on the wall boundaries surrounding mold cavity. Therefore, in the present study, a physical modeling of the filling process of powder/polymer mixtures was developed to take into account both the yield stress and slip phenomena and a finite element formulation was developed accordingly. The numerical analysis scheme for filling simulation is accomplished by combining a finite element method with control volume technique to simulate the movement of flow front and a finite difference method to calculate the temperature distribution. The present study presents the modeling, numerical scheme and some numerical analysis results showing the effect of the yield stress and slip phenomena.

Mechanical Properties and Formability of TWB Boron Steel (TWB 보론강의 기계적 특성 및 성형성)

  • Nam, K.W.;Hwang, S.H.;Kim, D.Y.;Lee, M.Y.;Lee, S.M.
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.36 no.10
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    • pp.1221-1226
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    • 2012
  • The hot-stamping technique is a forming method used for manufacturing high-strength parts, in which a part is cooled rapidly after press forming above the austenite transformation temperature. Boron steel, which contains a very small amount of boron, is one of the materials used for hot stamping. The purpose of this study is to investigate the mechanical properties of boron steel according to the heat-treatment conditions and the formability by using an Erichsen cupping test. Die quenching from various temperatures was conducted for different elapsed heat-treatment times. Laser-welded boron steel after quenching at 1173 K-0 s has a tensile strength of 1203 MPa. This is 79% of the tensile strength of the base metal (1522 MPa). The formability of boron steel was not significantly different from that at the mold temperature. However, it decreased with increasing forming speed. These properties provide practical information for the use of boron steels for hot stamping.

Exposure Characteristics for Chemical Substances and Work Environmental Management in the Semiconductor Assembly Process (반도체 조립공정의 화학물질 노출특성 및 작업환경관리)

  • Park, Seung-Hyun;Park, Hae Dong;Shin, In Jae
    • Journal of Korean Society of Occupational and Environmental Hygiene
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    • v.24 no.3
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    • pp.272-280
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    • 2014
  • Objectives: The purpose of this study was to evaluate the characteristics of worker exposure to hazardous chemical substances and propose the direction of work environment management for protecting worker's health in the semiconductor assembly process. Methods: Four assembly lines at two semiconductor manufacturing companies were selected for this study. We investigated the types of chemicals that were used and generated during the assembly process, and evaluated the workers' exposure levels to hazardous chemicals such as benzene and formaldehyde and the current work environment management in the semiconductor assembly process. Results: Most of the chemicals used at the assembly process are complex mixtures with high molecular weight such as adhesives and epoxy molding compounds(EMCs). These complex mixtures are stable when they are used at room temperature. However workers can be exposed to volatile organic compounds(VOCs) such as benzene and formaldehyde when they are used at high temperature over $100^{\circ}C$. The concentration levels of benzene and formaldehyde in chip molding process were higher than other processes. The reason was that by-products were generated during the mold process due to thermal decomposition of EMC and machine cleaner at the process temperature($180^{\circ}C$). Conclusions: Most of the employees working at semiconductor assembly process are exposed directly or indirectly to various chemicals. Although the concentration levels are very lower than occupational exposure limits, workers can be exposed to carcinogens such as benzene and formaldehyde. Therefore, workers employed in the semiconductor assembly process should be informed of these exposure characteristics.

Metal Injection Molding Analysis of WGV Head in a Turbo Charger of Gasoline Automobile (가솔린 자동차 터보차져용 WGV Head의 금속 분말 사출성형 해석)

  • Park, Bo-Gyu;Park, Si-Woo;Park, Dae-Kyu;Kim, Sang-Yoon;Jeong, Jae-Ok;Jang, Jong-Kwan
    • Transactions of the Korean Society of Automotive Engineers
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    • v.23 no.4
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    • pp.388-395
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    • 2015
  • The waste gate valve (WGV) for gasoline vehicles operate in a harsh high-temperature environment. Hence, WGVs are typically made of Inconel 713C, which is a type of Ni-based superalloy. Recently, the metal injection molding (MIM) process has attracted considerable attention for parts used under high-temperature conditions. In this study, an MIM analysis for the head and other parts of the WGV is conducted using a commercial CAE program Moldflow. Further, optimal manufacturing conditions are determined by analyzing flow characteristics at various injection times and locations. Moreover, to improve the accuracy of the analysis results, we compare the actual temperature of the mold during injection processing with that observed through the analysis. As the results, metal injection patterns of analysis are well in accord with these of short shot test. And the temperature variations of analysis is also very similar with those of feedstock when metal injection molding.