The ability of liquid metal to flow under its own weight is called "fluidity". The test and performance of fluidity is the ability of the alloy liquid to flow to fill the mold and the distance it can flow. The better the fluidity, the longer the distance it can fill and flow.
The fluidity of the alloy liquid is determined by the composition of the liquid metal, the solidification method, the shape of the primary crystal, the trace elements, the impurity content, the viscosity of the alloy liquid, the surface tension, the surface oxidation characteristics, the pouring temperature and its physical properties (latent heat of fusion, specific heat and thermal conductivity). The fluidity itself has nothing to do with external factors. Just like the fluidity of cement slurry and water, it is determined by its own characteristics. The fewer the trace elements of the die-casting alloy and the metal oxides in the alloy liquid, the smaller the solid phase particles of metal compounds and other contaminants, the better the fluidity of the alloy liquid.
However, external factors such as pressure and temperature will affect the solidification and cooling method of the alloy (roundness of the primary crystal shape), solidification speed, viscosity of the alloy liquid, surface tension and surface oxidation, and change the fluidity of the alloy liquid. The characteristic of the die casting process is that the pressure of die casting filling will increase the fluidity of the alloy liquid, and the mold cooling temperature, heat dissipation speed, cavity flow obstruction, cavity gas pressure, casting wall thickness, etc. will reduce the actual fluidity of the alloy liquid to varying degrees. For example, a higher mold temperature will reduce the degree of fluidity reduction. However, the fundamental external influencing factors are pouring pressure, pouring temperature, mold temperature and gas pressure that hinders flow.