Qingdao Dongfeng Water Supply Equipment Co., Ltd.

Introduction

"Lost Foam" is a casting process where foam (polystyrene) patterns are used to create the molds which hot molten metal dissolves, forming the object desired. This new process is very cost effective and can be used to create objects that traditional "Green Sand" casting has had difficulty replicating. These patterns can be formed by gluing separate foam pieces together to create complex patterns or can simply be carved out with traditional carving tools. Through the use of precisely molded foam pieces a highly accurate model or pattern for the desired casting can be made. This pattern can easily be sanded to create a fine finish to be represented on the final product. The foam is treated during the molding process by first pre-expansion, then a steam fusion followed by an in-mold cooling cycle. This stabilizes the foam to form perfect molds for casting. Once the pattern is created it is thoroughly coated with an insoluble ceramic solution to create a barrier for the molten metal not to pass through in the casting process. This coating also reinforces the structure of the pattern. After drying, the pattern is "invested" into a flask where un-bonded or dry sand is poured into the mold until every passageway inside and outside the pattern are completely covered with sand. Then through the use of a specially designed funnel (sprue), molten metal is poured in, which decomposes and vaporizes the foam piece allowing the metal to replace its shape. The pattern is then "lost" in the process. Once the casting hardens, the sand is removed; the component is inspected and very little machining is required in the finishing stages. Lost Foam casting can be pored with various metals to include: Iron, Aluminum and Copper-based alloys.