relates to a technology for casting large-size statue with metal shell

Expansion defects such as scab or fin are mostly studied from the standpoint of binder contents and properties.

In this paper, these defects in gray cast iron for automobiles were examined with green sand molds and shell molds, particularly from the point of view of feldspar content in silica sand. Hot toughness of molding sands increased by increasing the feldspar content in silica sand. This increase in hot toughness was caused by sintering of feldspar grains. It was effective for scab defects in green sand molds and shell molds. Where metal penetration and finning appears on the surface of shell cores which are surrounded by heavy metal sections, feldspar additions have cured the problem in most casess.

For example, adding 11% feldspar to silica sand reduced scabs on surfaces of shell cores which were used for transmission cases (about 25kg in weight). In the case of water jacket cores for cylinder heads and diesel engine blocks, it was necessary to add up to 11-37% where most severe finning and penetration occured. When these castings had extremely few holes for ejecting core sands, it was necessary not to add more than 27% of feldspar, because the jacket cores became less collapsible as a result of graze caused by fusion of the feldspar.

relates to a technology for casting large-size statue with metal shell. It uses a split draw-back molding process from sand casting method. A layer of filler whose thickness is identical to that of casting wall is laid on the surface of the internal cavity of its profile sand mold, then its core can be directly made in the internal cavity, and then the filler is removed, so that it can make processes of closing and pouring. Said invention is simple in molding process, low in production cost and has no need of making core box. Said statue can be once cast-molded, and its surface quality is good, form is really true