Excerpt from the University of Northern Iowa dissertation by Brodie J. Biersner.
Sand Mold Design
There are many molding methods available to produce a metal casting. The majority of metal castings however are produced with sand molds. This method for the production of metal casting has advanced over the years—from the materials utilized to the types of molding equipment and processes. Historically there was a lot of manual labor required for the production of a sand mold. Today, high speed molding machines are used with minimum amounts of human labor required. For sand casting to be successful for foundry applications, certain criteria must be met. The principal feature is good compatibility between the binder system and the sand aggregate chosen. This combination must also be compatible with the metal alloy used to produce the casting.
There are multiple purposes for a sand mold. The main purpose of a mold is to hold liquid metal in a specific shape until the metal solidifies. Sand molding can be broken down into two main categories: permanent and expendable. Permanent molds can be reused after the casting is solidified and removed, while in the expendable process the mold is destroyed. There are two methods that are predominant in expendable mold processes. One process uses an aggregate with a polymer/plastic and mixes the products together and allows the polymer to harden, or react. The other process mixes an aggregate with a mixture of bentonite clay and water. Known as green sand molding, this process produces the greatest amount of castings by weight.
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The Hill and Griffith Company's green sand metal casting foundry supplies help achieve the EPA's M.A.C.T. standards and reduce Benzene emissions. Our variety of environmentally sound release agents, coatings, partings, lubricants, core oils and specialty products will help you meet your metal casting's needs. We're known for our hands-on approach. Let us visit your plant and recommend products that suit your needs.
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On-site casting defect investigations, product testing, machine start-ups and much more. Also, lab facilities are available to provide testing upon request.
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