WATER SOLUBLE MANDRELS FOR MIXED-MATERIAL

摘要

a first mold on which mold release is covered; vinyl is covered on the mold release; gypsum for performing surface-hardening of the mold; a polyvinyl liquid of 5 to 10%, covered on the surface-hardened mold; and a second mold made by sand, polyvinyl alcohol of 5 to 10%, and a mixing material which is mixed in ratio 10~13 to 1, deformed after hardening is completed, and joined with an aluminum boss.