Patent ID: 7360577

Claim:
In the process for the-lost foam casting of a metal melt selected from the group consisting of aluminum, magnesium and their alloys comprising the principle steps of (a) embedding a pyrolyzable polymeric foam pattern in a mold comprising a bed of unbonded refractory particles to form a molding cavity in said bed, and (b) introducing said melt into said molding cavity to pyrolyze said foam into pyrolysis products, displace said pattern with said melt and shape said melt in said cavity, the improvement comprising: positioning a chill having a cooling face opposite a selected surface of said pattern such that said cooling face confronts said selected portion and is spaced from said selected surface by a gap having a width greater than 0.5 mm; introducing said melt into said gap so as to displace any pyrolysis products in said gap away from said cooling face and prevent entrapment of pyrolysis products by said melt against said face.