Metal casting methods, tooling and processes

Abstract From the Canadian patent

core assembly is formed by fabricating a first core molding a destructible plastic layer around the first core and, molding a second core around the plastic layer. The plastic layer is interlocked with an irregular outer surface of the first core, and the second core is interlocked with an irregular outer surface of the plastic layer. The core assembly can be used for casting engine cylinder heads to eliminate the need for gluing cores together and the accompanying formation of fins within fluid conducting passages.