Silica Sand / FOUNDRY
Foundry Silica Sand
High purity silica sand used for mold and core making in the foundry industry. Superior refractory properties with 98%+ SiO₂ content.
Technical Specifications
Key Features
- High SiO₂ purity (98%+)
- Low thermal expansion
- Provides good surface finish
- High refractoriness (1700°C+)
- Regular grain shape (round-angular)
- Low clay and dust content
Applications
- Green sand molding
- Resin bonded (shell molding)
- Cold box core production
- Hot box core production
- Investment casting
- Steel casting molds
Dimension Table
| AFS Grain Number | Mesh Size | SiO₂ (%) | Application |
|---|---|---|---|
| 30-35 | 20-40 mesh | ≥98 | Heavy casting, steel casting |
| 40-45 | 30-50 mesh | ≥98 | General casting, iron casting |
| 50-55 | 40-70 mesh | ≥98 | Medium-fine casting, aluminum casting |
| 60-70 | 50-100 mesh | ≥98 | Fine casting, core production |
Technical Notes
- 01Lower AFS number means larger grain size.
- 02AFS 30-45 range preferred for steel casting.
- 03AFS 50-70 range is ideal for aluminum casting.
- 04Moisture content should be kept below 0.3%.
- 05Clay content adjusted to 8-12% for green sand molding.
Other Types
What is foundry silica sand (moulding sand)?
Foundry silica sand is a high-purity refractory sand (SiO₂ ≥ 95–99%) used in foundries to make moulds and cores. Its high melting point (~1710°C), thermal stability and controlled grain size (measured by AFS grain fineness number) let it withstand molten metal. Mixed with a binder (bentonite, resin, sodium silicate) it forms green sand, chemically bonded sand or CO₂ moulds.
Grain size (AFS), composition and casting quality
Three factors drive moulding-sand performance: SiO₂ purity (surface finish and refractoriness), grain size/distribution (AFS GFN — the balance between permeability and surface roughness) and grain shape. Fine sand gives a smoother surface but lower permeability; coarse sand the opposite. Clay and moisture content affect mould strength and gas defects. The right sand–binder recipe directly determines the dimensional accuracy and surface quality of the casting.
Frequently Asked Questions
What is the difference between foundry sand and construction silica sand?+
Foundry sand needs higher SiO₂ purity, controlled grain size (AFS) and refractoriness; unlike construction/glass sand it is selected to withstand molten metal.
What is the AFS grain fineness number (GFN)?+
An index of the average grain size of the sand; a higher AFS = finer sand = smoother surface but lower permeability.
Which binders are used in moulding sand?+
Bentonite + water for green sand; furan/phenolic resin for chemically bonded sand; sodium silicate (water glass) for the CO₂ process.
What SiO₂ content should silica sand have?+
Typically 95–99% SiO₂ for casting; higher purity gives better refractoriness and surface quality.
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