Through analyzing the cooling characteristics of the silica shell

based on hydrodynamic equations

it is derived that the liquid steel during filling process and the heat exchange time between ingate wall is proportional to the liquid steel in ingate

which affects the over-heat of flow channel near the ingate

resulting in occurrence of shrinkage porosity.The mass flow density is adopted to check area and number of ingate.It is acceptable for mass flow density less than 0.4×104 kg/m2.Application of the mass flow density in the heat riser

ladder

bottom-pouring

multi-ingate

and composite gating system as well as balance pouring

hot flow channel was presented to effectively eliminate the shrinkage porosity in ingate and flow channel.Due to having considered parts weight in application of mass flow density in ingate

the parts on the assemble tree are not fall out as a result of large weight of parts with small hot spot size and small total ingate area.