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

• Korean Journal of Materials Research
• /
• v.16 no.11
• /
• pp.698-704
• /
• 2006

In this study, the effect of chill layers occurred in shot sleeve on the molten metal filling was analyzed through computer simulation. The behavior of chill layers with temperature variation of shot sleeve set from 200 to $280^{\circ}C$ was also investigated. The simulation results showed the chill layers set in the in-gates during the injection process change the main filling direction and cause turbulent flow pattern, resulting in porosities inside the castings. The amount of chill layers with the increasing temperature of shot sleeve was considerably reduced. Particularly, at the setting temperature of $280^{\circ}C$ by heat control unit, the biggest reduction in chill layers, excellent trimmed surface and the highest density were achieved, suggesting that as the optimal sleeve condition in aluminum high pressure diecasting, especially for highly complex parts like valve body.

• Journal of the Korean Society of Manufacturing Process Engineers
• /
• v.14 no.5
• /
• pp.1-7
• /
• 2015

Cleaning by injecting dry ice and water is a generally adopted trend these days to clean molds (injection, diecasting foundry, press, rubber mold, etc). This cleaning method is performed manually, or by installing multiple high pressure spray nozzles. We have manufactured a turbine cleaning module device that is able to clean diecasting modules at any position and angle in the space by mounting an articulated robot instead of the existing pipe type injection nozzle, to minimize lead time and enhance working yield of the cleaning process. In this paper, we analyzed process factors that are required to design the turbine module by reviewing number of revolution, and results according to different blade angles and thicknesses of the mold release injection turbine module, using computational fiuid dynamics (CFD).

• Journal of Korea Foundry Society
• /
• v.28 no.3
• /
• pp.136-140
• /
• 2008

A new concept of salt core, a melting temperature of which is lower than the solidus temperature of cast alloy, was introduced to produced an integrated casting part having a complicated inner shape or requiring under-cut in high pressure die casting or squeeze casting process. The main goal of this study is to develop a new integrated net-shape forming technology using fusible core of lower melting temperature than that of a casting alloy. This integrated net-shape forming technology would be very successful and cost-effective for producing the integrated products having a complicated inner shape or requiring under-cut. The technology for measuring and evaluating a various property of fusible core such as a thermal conductivity and thermal expansion coefficient, melting temperature was established. Also, the work space can be cleaned without a pollution inducing products.

• Journal of Korea Foundry Society
• /
• v.28 no.6
• /
• pp.256-260
• /
• 2008

The Hybrid-Lower Arm, which has been developed for reducing cost and weight, was produced by three kinds of casting methods such as the high-pressure diecasting(HPDC), the squeeze casting(SC), and the H-NCM rheocasting process. The important factors for development of the Hybrid-Lower Arm are the integral feeding in Al casting for heat treatment and the high joinning ratio between the steel part and the Al part. In this study, effects of these casting processes on the quality of Hybrid-Lower Arm were investigated. Compared with HPDC and squeeze casting, the rheocasitng process using the H-NCM slurry had some advantages in joinning different materials of Al and steel pipe without deforming the steel pipe. X-ray analysis also showed the poreless microstructure in semisolid Hybrid-Lower Arm. In the torsion stress test, semisolid Hybrid-Lower Arm was satisfied with the requirements of automobile standard.

• Journal of Korea Foundry Society
• /
• v.31 no.1
• /
• pp.11-17
• /
• 2011

The effect of CaO addition to AM60B Mg alloy on tensile properties has been investigated, with focus on strength and ductility at room and elevated temperatures. The 0.25-0.65wt% CaO added AM60B Eco-Mg diecastings were prepared by high pressure die casting using Buhler 1,450-ton cold chamber machine without $SF_6$ and $SO_2$ gases. The microstructures and tensile properties of each alloy were tested. The results show that the grains of AM60B are refined and the mechanical properties increase with CaO addition at room temperature. The improvement of strength and ductility is prominent at 0.45-0.55wt% CaO addition. Also, improved mechanical properties are maintained at elevated temperature of $150^{\circ}C$. CaO addition results in $Al_2Ca$ phase formation mostly on the grain boundaries. This phase leads to the refinement of grain structures and improvement of ductility as well as strength. The suppression of ${\beta}-Mg_{17}Al_{12}$ phase as well as the decrease of fracture surface porosity and other casting defects caused by melt cleanliness also contribute to the enhancement of mechanical properties of AM60B Eco-Mg at room and elevated temperature.

• Journal of Korea Foundry Society
• /
• v.27 no.1
• /
• pp.31-35
• /
• 2007

In order to develop the semi-solid forming technology for magnesium alloy the rheological and thixotropic behavior of Mg alloy slurry with varying shear rates and cooling rates was investigated and simulated with considering the viscosity based on microstructures and processing variables. The viscosity of slurry of Mg alloy (AZ91D) in semi-solid region was exponentially increased with a solid fraction, and was decreased with increasing a shear rate. In order to analyze precisely the rheological behavior, the ANYCAST program modified with the Carreau model and the different heat transfer coefficient between the cast and mold was used to simulate the flow behavior of Mg semi-solid slurry during the injection into a casting mold in a high pressure diecasting machine. The simulated rheological behavior of Mg alloy slurry was matched well with the experimental results.