Foundry sand is a composite refractory material primarily composed of silica sand (quartz sand), along with various non-silica sands and artificial sands.
Main Classifications of Foundry Sand Materials
1. Silica Sand (Quartz Sand)
Natural silica sand: Contains a silicon dioxide (SiO₂) content generally exceeding 90%. Used as molding sand and core sand for non-ferrous metal castings, iron castings, and small and medium-sized steel castings.
Washed silica sand: Contains a mud content ≤1.0%, suitable for general casting.
Scrubbed silica sand: Contains a mud content <0.5%, suitable for precision casting.
Calcined silica sand: High-temperature treated at 850°C, suitable as a base material for resin sand production.
2. Non-silica Sand
Chromium ore sand: Contains Cr₂O₃ ≥35%-45%, exhibits alkaline slag resistance, and is used as facing sand for large steel castings.
Limestone sand: Contains CaCO₃ as its main component and is widely used in steel casting production. Corundum sand: High in α-Al₂O₃ content, used for investment casting shells.
3. New Artificial Sand
Ball sand: Made from bauxite, melted at 2000°C, it features spherical particles and high permeability, making it an alternative to traditional quartz sand.
Red sand: With a silica content of ≥79.4%, it offers a refractoriness of up to 1440°C and is used for precision castings such as automotive engine blocks.
Functional Properties and Auxiliary Ingredients
Foundry sand must be combined with a binder (such as clay, resin) and additives (coal powder, sawdust) to meet the following performance requirements:
Refractory: Resists corrosion from high-temperature liquid metal.
Permeability: Allows for the removal of gases generated during pouring.
Collapsibility: Allows for easy cleaning of the sand mold after the casting cools.
Of course, sand selection requires a comprehensive consideration of material properties, process requirements, and cost. For high-precision castings, coated sand (with dimensional accuracy up to CT6) is preferred, while highly automated resin-bonded sand systems are recommended for large-scale production. The above materials are essentially different from ordinary sand. If you need to customize large quantities of metal castings, you can choose to cooperate with Mulan Metal. Mulan Metal has 12 years of casting processing experience and has helped customers in more than 30 countries complete casting processing business support and received unanimous recognition. We look forward to your cooperation consultation.
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