The flow and temperature change behaviors of molten aluminum flowing through a thin cavity, as in intake manifold castings, were investigated.
  Molten metal flows through a thin cavity at a constant rate in the liquid state. However molten metal is cooled to the solidifying temperature, the flow rate rapidly decreases till the flow stops. The molten metal temperature decreases at a constant cooling rate in proportion to the flowing time, regardless of the casting temperature and the flow rate. The cooling rate of molten metal is determind by the thickness of the mold cavity. For a shell mold with the cavity thickness of 8 to 3mm, the cooling rate varied from 40 to 160°C/s. For a intake manifold castings made with a die and a shell mold core, it was 40 to 50°C/s. However, the molten metal temperature hardly decreases after solidification is started due to the radiation of latent heat.