Three stage filling morphology In the first stage, after the metal flow limited by the area of the inner gate is injected into the mold cavity, it first impinges on the opposite mold wall, extending in all directions along the mold surface. When the mold cavity has the correct thermal balance j, a surface layer is formed on the mold wall through which the metal flows, which is the outer shell (thin shell) of the die casting. This stage affects the surface quality of the die casting. In the second stage, the subsequently injected liquid metal continues to deposit in the space within the thin shell layer for filling until it is filled, which affects the hardness of the die casting. In the third stage, while the mold cavity is fully filled, pressure acts on the die casting through the central portion that is not yet solidified, and the metal in the mold cavity is compacted. This stage affects the strength of the die casting. The experimental results of the three stage filling theory and t…