High-pressure die casts exhibit a certain amount of porosity, which can reduce their mechanical properties. One of the options for maintaining the porosity of casts at a low value is the correct gating system design. Presented contribution is based on the conclusions of the “Methodology assessment of the gating system numerical design of high-pressure die casting with regard to the material applicability” contribution. Individual numerical design methods gave different dimensions and cross-sections for the runners. Based on the assumption of a Reynolds number Re modification when altering the hydraulic cross-sections of the runners, it is possible to conclude that the nature of the melt flow in the runners is also shifting. The presented contribution aims to analytically determine the hydrodynamic conditions in the melt with different designs of the gating systems, determine the filling mode of the mold cavity and subsequently, using a simulation program, to determine the share of gas entrapment in the casts volume. At the end of the contribution, assumptions are deduced about the mechanism of gas entrapment in the casts volume.
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