Binder composition and method of forming foundry sand cores and molds

Abstract

A cost-effective starch / water-based binder composition and related method for forming silica sand cores and molds for foundries, wherein the sand grains are pre-coated with starch having additives making the coated sand effective for blowing said cores and molds. One or more additives are included with the starch; preferably sodium tripolyphosphate and silicon or Silres BS16. The preferred starch is a tapioca starch. The binder of the invention is highly competitive due to its low cost and effectiveness for forming silica-sand cores and molds, being particularly effective for use in aluminum foundries for the automotive industry.

Description

FIELD OF THE INVENTION[0001]The present invention refers to a binder and a method of forming foundry sand cores and molds, and more particularly to a water-based binder and a method of forming silica sand cores and molds with great economic and environmental advantages over the currently used organic-compound binders.BACKGROUND OF THE INVENTION[0002]The automotive industry is extremely competitive and demanding regarding manufacturing costs of automobile components. The manufacturers of cylinder engine blocks and heads, mainly made of aluminum alloys, are constantly looking for methods and systems that provide cost savings and simultaneously increase the quality of such engine parts.[0003]One of the preferred processes for manufacturing engine blocks and heads utilizes silica sand molds and cores. Currently, the molds and cores are most typically made of silica sand grains bound by a heat-curable phenolic binder or a gas activated cold box binder. The heat-curable binders have the d...

AI Technical Summary

Benefits of technology

[0015]It is therefore an object of the present invention to provide a competitively effective water-soluble binder composition for forming sand cores and molds for foundries with several cost and technical advantages plus environmental benefits, as well as the method of making such cores and molds and the cores and molds made with such composition.

[0016]It is another object of the present invention to provide a method of forming sand cores and molds for foundries at a lower cost.

[0018]It is still a further object of the invention to provide a method, a binder composition, and sand cores and molds for foundries for producing castings with dimensional precision that advantageously avoids the need to use higher-cost zircon sand to obtain comparable results.

Problems solved by technology

The automotive industry is extremely competitive and demanding regarding manufacturing costs of automobile components.

The heat-curable binders have the disadvantage of requiring heat to set the molds and cores, producing foul-smelling vapors, and requiring special anti-pollution equipment to prevent ambient contamination.

Another disadvantage arises once the cast motor blocks or heads are solidified, since removal of such cores and molds needs additional heat to burn off the binder by contact with hot air (in order to combust the binder and thus loosen the sand to destroy the cores), thus adding further to the fuel cost of the process.

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