• Design & Manufacturing
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• v.13 no.2
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• pp.49-53
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• 2019

The temperature distribution and lifetime of molds were predicted by computer simulation analysis with various spraying and blowing process of high pressure die casting. After varying the spraying angle and time, the mold temperature, heat exchange and mold life were predicted. As the spraying angle increases, the maximum temperature of the mold decreases, which is because the spraying area increases and the heat exchange with the mold increases. Heat exchange occurs more actively in the blowing process than in the spraying process. This is because the cooling is not performed due to the steam generation. When the spraying angle is 50 degree, the minimum life of the mold is analyzed 200 times. After adjusting the blowing time from 5s to 3s, the minimum lifetime of the mold has been increased almost twice.

• Journal of Korea Foundry Society
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• v.18 no.3
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• pp.228-233
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• 1998

• Journal of the Korean Society for Heat Treatment
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• v.37 no.3
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• pp.121-127
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• 2024

We investigate the effect of T6 heat treatment on the microstructure and mechanical properties of AA365 (Al-10.3Si-0.37Mg-0.6Mn-0.11Fe, wt.%) alloy fabricated by vacuum-assisted high pressure die casting by means of thermodynamic calculation, X-ray diffraction, scanning and transmission electron microscopy, and tensile tests. The as-cast alloy consists of primary Al (with dendrite arm spacing of 10~15 ㎛), needle-like eutectic Si, and blocky α-AlFeMnSi phases. The solution treatment at 490 ℃ induces the spheroidization of eutectic Si and increase in the fraction of eutectic Si and α-AlFeMnSi phases. While as-cast alloy does not contain nano-sized precipitates, the T6-treated alloy contains fine β' and β' precipitates less than 20 nm that formed during aging at 190℃. T6 heat treatment improves the yield strength from 165 to 186 MPa due to the strengthening effect of β' and β' precipitates. However, the β' and β' precipitates reduce the strain hardening rate and accelerate the necking phenomenon, degrading the tensile strength (from 290 to 244 MPa) and fracture elongation (from 6.6 to 5.0%). Fractography reveals that the coarse α-AlFeMnSi and eutectic Si phases act as crack sites in both the as-cast and T6 treated alloys.

• Journal of Korea Foundry Society
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• v.20 no.6
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• pp.400-406
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• 2000

Computer simulation for the predictions of casting defects is very important to produce high quality castings with less cost. Complicate shaped Al solenoid housing part was selected to be cold chamber die cast and a numerical simulation technique was applied for the optimization of the chill vent position and gating. A first design led to insufficient central flow. This flow left the last filled areas falling into the inner portion of the part. And last filled area did not fit the chill vent position. So these resulted in a high possibility of air entrapment in the casting and the design was not proper for the part. The design was improved by using a proper gating system, a more chill vent and proper overflow positions. New design provided a homogenous mold filling pattern and the last filled areas that being located at the overflow and chill vent. Casting plan which produce good quality solenoid housing part was established by using the computer simulation.

• Journal of Mechanical Science and Technology
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• v.20 no.10
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• pp.1765-1772
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• 2006

High-pressure die casting such as thixocasting and rheocasting is an effective process in the manufacturing automotive parts. Following the recent trend in the automotive manufacturing technologies, the product design subject to the die casting becomes more and more complex. Simultaneously the injection speed is also designed to be very high to establish a short cycletime. Thus, the requirement of the die design becomes more demanding than ever before. In some cases the product's shape can have multiple slender manifolds. In such cases, design of the inlet and outlet parts of the die is very important in the whole manufacturing process. The main issues required for the qualified products are to attain gentle and uniform flow of the molten liquid within the passages of the die. To satisfy such issues, the inlet cylinder ('bed cylinder' in this paper) must be as large as possible and simultaneously the outlet opening at the end of each passage must be as small as possible. However these in turn obviously bring additional manufacturing costs caused by re-melting of the bed cylinder and increased power due to the small outlet-openings. The purpose of this paper is to develop effective simulation methods of calculation for fluid flows in multiple columns, which mimic the actual complex design, and to get some useful information which can give some contributions to the die-casting industry. We have used a commercial code CFX in the numerical simulation. The primary parameter involved is the size of the bed cylinder. We will show how the very small opening of the outlet can be treated with the aid of the porous model provided in the code. To check the validity of the numerical results we have also conducted a simple experiment by using water.

• Journal of Korea Foundry Society
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• v.40 no.3
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• pp.66-75
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• 2020

The aim of this study was to optimize a solid solution treatment for a high pressure die casting Al-10Si-0.3Mg-0.6Mn alloy to avoid blistering and to improve the strength of the alloy. To achieve this goal, the number density of the blisters and the strength of the alloy under various solid solution treatment (SST) conditions were evaluated. The SST was performed at 470, 490, 510 and 530℃ for 20, 60, 120, 240 and 480 min on the alloy. The number density of the blisters increased with the increasing temperature and time of the SST and the defect area fraction. The yield strength of the alloy after the T6 heat treatment increased with the increasing SST temperature and time. Based on the results, it is suggested that SST should be performed at 510℃ within 60 min. or at 470 and 490℃ within 240 min. to avoid blistering and to improve the strength.

• Journal of Korea Foundry Society
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• v.28 no.4
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• pp.166-169
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• 2008

This study deals about the development of fusible core with low melting temperature by addition of ceramic particles. A new concept of salt core was introduced to produce an integrated casting part having a complicated inner shape or requiring under-cut in high pressure die casting or squeeze casting process. The mechanical properties of fusible core were improved due to the addition of ceramic particles which helped to produce fine microstructure. The new technology for the preparation of new fusible core materials which possess high compression strength was established. Addition of ceramics particles increased the mechanical properties of fusible core materials. There was an increasing relationship between percentage of ceramic particles and mechanical strength was existed up to 60%.

• Journal of Korea Foundry Society
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• v.16 no.6
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• pp.550-555
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• 1996

A stochastic model, based on the coupling of the finite volume(FV) method for macroscopic heat flow calculation and a two-dimensional cellular automaton(CA) model for treating microstructural evolution was applied-for the prediction of microstructural evolution in squeeze casting. The interfacial heat transfer coefficient at the casting/die interface was evaluated as a function of time using an inverse problem method in order to provide a quantitative simulation of solidification sequences under high pressure. The effects of casting process variables on the formation of solidification grain structures and on the columnar to equiaxed transition of an Al-4.5wt%Cu alloy in squeeze casting were investigated. The calculated solidification grain structures were in good agreement with those obtained experimentally.

• Journal of Korea Foundry Society
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• v.31 no.6
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• pp.354-361
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• 2011

The liquid metal shearing device was constructed and assembled with a commercial high-pressure die-caster in order to induce intensive turbulent shearing force on molten aluminum alloys. The effect of the liquid metal shearing on the microstructure and tensile properties of A356 alloys was investigated with the variation of iron content. The experimental results show that dendritic primary ${\alpha}$-Al phase was effectively modified into a equiaxed form by the liquid metal shearing. It was also found that the needle-like ${\beta}$-AlFeSi phase in a Fe containing A356 alloy was changed into a blocky shape resulting in the improved mechanical properties. Based on the mechanical properties, it was suggested that the iron content in A356 alloy could be more widely tolerated by utilizing the liquid metal shearing HPDC process.

• Journal of Korea Foundry Society
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• v.24 no.4
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• pp.238-248
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• 2004

고압 다이캐스팅에서 요구되고 있는 고품질의 주조를 위해, 비교적 간단한 개선 방안으로 용탕 주입 방법의 개선이 실험적으로 시도 되었으며, 그로 인해 많은 경우에 긍정적인 결과가 관찰 되었다. 특히, 냉가압 다이캐스트에서, 금형내 용탕의 예충전을 유도하는 용탕 주입의 속도 및 플렌저의 위치제어를 통해 기공율의 저하 및 그로 인한 기계적 강도의 개선 효과를 확인 할 수 있었다. 본 논문은, 그 원인과 결과 대한 연구를 위해, 상용 해석 도구인 Flow3D를 이용, 금형내 용탕의 흐름을 모델링을 통해 가시화하여 용탕의 주입속도 및 위치의 변화가 주물의 품질에 미치는 영향을 조사하였다. 용탕 주입을 위한 플런저의 속도 및 위치 제어의 변수로, 1) 금형내에 용탕의 예충전 유도를 위한 용탕 고속 주입 지연 정도, 2) 플런저의 저속운행에서 고속으로의 가속도, 3) 용탕의 예충전 동안의 플런저 속도를 선택, 그로 인한 영향을 연구 분석 하였고, 그 결과로 플런저의 속도 및 위치 조절을 통하여 금형내 갇힌 공기의 양이 줄어 들 수 있음을 알 수 있었다.