| The effects of the viscosity, gate speed, and gate geometry on the flow behaviors of the molten and the semi-liquid A356 Al alloys were studied. Two different fluids, i.e. thixotropic fluid(semi-liquid A356 Al alloy) and Newtonian fluid(molten ADC12 Al alloy), were chosen as the model fluids for monitoring the difference in flow patterns during die filling. High speed photography was employed to elucidate the real time flow patterns of the molten and the semi-liquid alloys during die filling sequence. The effects of the gate speed of the incoming fluid and the gate geometry on the die filling characteristics were investigated. In the case of the fluid flow exhibited by the semi-liquid A356 Al alloy, die filling was observed to proceed in a laminar manner while maintaining its free surface. In the case of the molten Al alloy, however, the leading edge of the fluid was completely shattered even at a relatively low injection speed, resulting in die filling accompanied by turbulence. |
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