An improved model for predicting heat transfer coefficient peak value at the casting-die interfaces

Abstract

An improved model is developed to accurately predict the interfacial heat transfer coefficient peak value (<i style="mso-bidi-font-style: normal">h</i>_{<span style="mso-bidi-font-style: italic" lang="EN-GB">max</span>}) at the casting-die interface during the solidification of light alloys. To develop the improved model, a new method is proposed to simplify the profile of die surface. The effect of surface tension on the predicted <i style="mso-bidi-font-style:normal">h</i>_{<span style="mso-bidi-font-style:italic">max</span>} is considered quantitatively in this model. The improved model has been applied to high pressure die casting and gravity die-casting processes. The calculated <i style="mso-bidi-font-style:normal">h</i>_{<span style="mso-bidi-font-style:italic">max</span>} of the improved model tends to have higher accuracy than those of the previous model and show good agreements with the experimental results in both cases. The results suggest that the new method used to simplify the surface profile in the improved model makes a major contribution to improve the prediction accuracy. Surface tension is also found to have a certain effect on the calculated <i style="mso-bidi-font-style:normal">h</i>_{<span style="mso-bidi-font-style:italic">max</span>}<span style="mso-bidi-font-style: italic"> in gravity die-casting process, but no effect in high pressure die casting process. Its effect appears to decrease with increasing applied pressure.

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