Research on the relationship between sprue conditions and casting defects by means of observation of the titanium flow in a mold cavity

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By means of the tracer element molten method, the titanium flow behavior in the mold cavity can be clarified and the obtained results provide the mechanism of the several defects of titanium castings.In this period, we investigate the relationship between the casting defects and the titanium flow affected by the sprue conditions. The characterization of a centrifugal casting machine has become clear because of its laminar flow. In spite of the casting mechanism of each casting machine, pressure casting machine or centrifugal casting machine, the molten titanium was moved partly by its velocity obtained in sprue and partly by the internal pressure. Each part has been governed by the shape of the cavity, casting machine, and flow condition (laminar or turbulent). In thick plate, even in the case of the pressure casting machine, molten titanium moves by its velocity because of small flow resistance. The pipe like casting was made by the part of molten titanium which obtained the excess velocity. In the mesh type cavity, the internal pressure of the molten titanium was very important for smooth flow and castability. Furthermore, each part of the casting areas which were moved by the driving force of either the velocity or the internal pressure was very clear by the use of the centrifugal casting. In conclusion, when we investigate the complete titanium casting, we must always concern the driving force, the velocity of molten titanium or the internal pressure.