Prediction of gas entrapment defects during zinc alloy high-pressure die casting based on gas-liquid multiphase flow model

Abstract

Zinc alloy is the preferred material for high-pressure die-casting (HPDC) production because of its good casting and mechanical properties, and the most common problem in zinc alloy die casting is gas entrapment. A gas-liquid multiphase flow model was here used to predict the gas entrapment defects during the zinc alloy HPDC filling process, and the continuum surface force (CSF) model was used to treat the surface tension of gas-liquid multiphase. In addition, finite volume method (FVM) was used for discretization equations; the pressure implicit with splitting of operator (PISO) algorithm was used for coupling pressure and velocity; and the volume of fluid (VOF) algorithm was used for interface tracking. A water-filling experiment was simulated in an S-shaped channel, and the simulative results were closely consistent with the experimental results, which indicate the accuracy of the adopted model. Two HPDC zinc alloy-filling processes with different ingates were calculated, and the simulative results showed that gas entrapment defects associated with a single ingate were visibly more pronounced than with double ingates, which was basically consistent with the experimental results; therefore, the practicability of the adopted model was confirmed.