Resin coated sand for shell foundry process

Abstract From the Canadian patent

An improved resin coated sand for use in foundry shell-molding applications is disclosed which has increased resistance to thermal shock at the time of pouring. The improved product uses a phenolic resin as binder with aromatic compounds selected from the following generic formulae: The foundry aggregates are mixed with the phenolic resin and organic compounds under conventional mixing conditions to form a sand-resin mixture that can be formed into shell-molds. Upon casting the molten metal into these molds the abrupt, thermal expansion of the coated sand is controlled to eliminate the cracking that occurs when conventional phenolic-sand mixtures are employed.