Aluminum High Vacuum Die-casting process has become more prevalent in automotive manufacturing industry which require high productive rate, weldable process and heat treatment process. However, high pressure die castings usually contain gas porosity due mainly to the entrapment of air or gas in the die during the high speed injection of the molten metal into the die cavity. Vacuum block system with disk spring was developed and vacuum chanel was optimized with numerical flow analysis. The porosity of die castings was analyzed by X-ray CT, and the effect of porosity on the mechanical properties was analyzed by hardness and tensile test. Tensile strength was improved 49.5% for 50mbar high vacuum die-casting process compare then 300mbar. And then, Surface property was analyzed with plunger velocity and fast shot set point.

In order to develop a new commercial Al-12%Si casting alloy with improved physical properties, we investigated the effect of adding Sr and TiB to the alloy. Al-12%Si alloys were prepared by die casting at 660 oC. The eutectic temperature of the Sr-modified Al-12%Si alloy decreased to 9 oC and the mushy zone region increased. The shape of the Si phase changed from coarse acicula to fine fiber with the addition of Sr. The addition of TiB in the Al-12%Si alloy reduced the size of the primary α-Al and eutectic Si phases. When Sr and TiB were added together, it worked more effectively in refinement and modification. The density of twins in the Si phase-doped Sr increased and the width of the twins was refined to 5 nm. These results are related to the impurity induced twinning(IIT) growth.

In this study, the weldability of ADC12 FSW joints obtained by the load control type of the FSW machine is examined. The higher the tool plunge downforce the wider the range of the optimum FSW conditions is obtained. However, there is a limit of optimum range with increasing the tool plunge downforces. The three different types of defects are formed in ADC12 FSW joints, depending on the welding conditions. One is a large mass of flash due to the excess heat input, another is a cavity or groove-like defects caused by insufficient heat input and the other is a cavity caused by the abnormal stirring. As for the abnormal stirring, it is very clearly seen that the shape of the top part on the advancing side in the stir zone is completely different. For this type of defect, the effect of the tool plunge downforce is not significant, though the size of the defect due to insufficient heat input significantly is decreased with the increasing downforce

When manufacturing die casting mold, generally, the casting layout design should be considered based on the relation between injection system, casting condition, gate system, and cooling system. Also, the extent or the location of product defects were dif

When manufacturing die casting mold, generally, the casting layout design should be considered based on the relation between injection systems, casting condition, gating system, and cooling system. Also, the extent or the location of product defects will be differentiated according to the various relations of the above conditions. High-qualified products can be manufactured as those defects are controled by the proper modifications or the changes of die casting mold with the conditions. In this research, the proper manufacturing method intensively be derived for reducing the defect of the internal porosities issues of power steering which is very complicated to achieve the mold design, and for minimizing and for guaranteeing the product quality through the analysis of the problem of casting parts and the deduction of alternative plans.

The effect of the alloy systems Al-Mg alloy and Al-Si alloy in this study on the characteristics of die-casting were investigated using solidification simulation software (MAGMAsoft). Generally, it is well known that the casting characteristics of Al-Mg based alloys, such as the fluidity, feedability and die soldering behaviors, are inferior to those of Al-Si based alloys. However, the simulation results of this study showed that the filling pattern behaviors of both the Al-Mg and Al-Si alloys were found to be very similar, whereas the Al-Mg alloy had higher residual stress and greater distortion as generated due to solidification with a larger amount of volumetric shrinkage compared to the Al-Si alloy. The Al-Mg alloy exhibited very high relative numbers of stress-concentrated regions, especially near the rib areas. Owing to the residual stress and distortion, defects were evident in the Al-Mg alloy in the areas predicted by the simulation. However, there were no visible defects observed in the Al-Si alloy. This suggests that an adequate die temperature and casting process optimization are necessary to control and minimize defects when die casting the Al-Mg alloy. A Tatur test was conducted to observe the shrinkage characteristics of the aluminum alloys. The result showed that hot tearing or hot cracking occurred during the solidification of the Al-Mg alloy due to the large amount of shrinkage.