Effect of Molten Metal Stream Shrouding in Minimizing Surface Turbulence

The metalcasting process is one of the most complex manufacturing processes. It is characterized by numerous physical phenomena that need to be completely understood and controlled. The focus of this paper is on the fluid mechanics of the molten metal stream entering the mold cavity. The flow pattern of the molten metal has a profound effect on the quality of the end casting. This has prompted numerous research efforts in developing methods of delivering molten metal to the mold cavity in a way that will result in relatively fast flow and minimally disturbed stream of molten metal with a minimum of surface turbulence. This paper compares the conventional method of molten metal delivery to the mold cavity with the recently implemented shroud pouring technique. The experimental and numerical results are correlated for one casting manufactured by Harrison Steel Castings Co., Attica, Indiana. The results show the complexity of the filling process during the transient flow stage and the need to rely on the numerical simulation for a full understanding of the process. In addition, the results show certain benefits of the shroud pouring technique compared to conventional pouring, and that pouring parameters and alloy chemistry have significant impact on the quality of the casting.