Coupled Modeling of Misrun, Cold Shut, Air Entrainment, and Porosity for High-Pressure Die Casting Applications

Combined defect prediction for large-area die-cast components using high-resolution multi-phase simulation

“…It was extended to the dimensionless Niyama criterion by Carlson and Beckermann [11] and the Böttiger-Laqua-Jakumeit criterion [12] by one of the authors. The Niyama criterion were found to be not applicable for the porosity prediction in HPDC-applications [9]. Beckermann und Monroe [13] came to the same conclusion when developing a porosity model for HPDC-applications.…”

“…Above a solids content of 70%, the flow of the melt is completely stopped. The multi-phase approach used has been validated in various applications by comparison with casting results [9,23]. The coupled calculation of the melt and gas phase was used to develop a fully coupled porosity model: During mold-filling, pressure build-up and starting solidification, flow and pressure are calculated coupled in the melt and gas phase.…”

“…𝜌 + (𝑃 𝑐𝑟𝑖𝑡 − 𝑃) * 𝜕𝜌/𝜕𝑃 The pore gas phase is treated as a new ideal gas phase, which is separated from the melt phase by a VoF approach. The concept of this coupled porosity model was demonstrated for a cylindrical geometry in [9].…”

“…A special HPDC test geometry was designed to investigate misrun, gas entrainment and porosity in one geometry (see [9] for more details). Figure 1a gives a photo of the moving die of the test geometry and figure 1b the whole geometry with the four test geometries: two-hole geometry to investigate misrun and cold shuts, steps geometry for air entrainment and porosity analysis, three-cam geometry to enforce shrinkage porosity and U-profile geometry to analyze gas entrainment.…”

“…Modifications of this model are widely used in commercial casting simulation software. In fast solidification process like high pressure die casting (HPDC) with not negligible melt flow during solidification, the assumption that void gathers at the highest point is found to be not valid [9]. The Niyama criterion is a standard approach for micro-porosity prediction [10].…”