Design of Novel Gating Systems for Steel Castings

Gating systems play an important role in determining the quality and mechanical properties of castings. To understand the efficiency of gating systems, four systems, namely pressurized system, non-pressurized system, naturally pressurized system with a side riser and a naturally pressurized system with a top riser, were studied. The naturally pressurized systems were provided with overflows which collected the incoming metal swirl. Parameters like velocity of metal flow, air entrapment, microporosity and Niyama criterion were considered, and a design was developed with a common pouring basin. 8630 alloy was poured into two molds using a teapot ladle. The inclusion analysis revealed the presence of alumina and an alumina + manganese sulfide complex, and the naturally pressurized top riser system provided the cleanest casting with the best toughness. The formation of eutectic type II MnS affected the toughness properties. Naturally pressurized side riser and the non-pressurized system performed on par while the pressurized system had the highest inclusion area fraction.