Effect of mold media on solidification of A356 Al-Si alloy in Lost foam casting

摘要

The influence of selected mold materials on solidification of A356 was investigated for vertical lost foam casting (LFC) plate-patterns of different thicknesses. The basic thermal properties and heat diffusivity of mold medium were seen to affect the total solidification time and cooling rate. In this research, Chvorniov's rule was modified for LFC. The endothermic nature of foam casting (decreasing the superheat of liquid metal) and the heat transfer coefficient value in mold metal interface together necessitate modification of the rule. Besides, it was shown that the total solidification time was significantly lower at low casting modulus for Mullite 40 than for silica sand, however it was slightly higher for Mullite 40 at high casting modulus. During casting, the superheat decreased rapidly for lower thickness of the foam pattern compared with higher thickness. These observations are explained using energy balance relation between foam and liquid metal.