Silica Sand
High-Purity Silica Sand
AFS (American Foundry Society) numbers denote the average grain fineness of foundry sands, especially silica sand, used in casting and industrial applications. A lower AFS number means coarser grains; a higher AFS number means finer sand grains. Below is comprehensive information on your requested AFS grain bands, focusing on their typical properties, usage, grain size distribution, and composition.
30-35 AFS
- Typical Use: Common in foundries for molding, welding, and casting applications.
- Grain Size Range: Average grain size is approximately 450-600 µm, with a low clay content (0.1-0.2%).
- Chemical Composition: Silica content near 100%, supplied as granular or dust form, hardness 0-3 Mohs.
- Packaging: Typically packed in HDPE or 10 kg bags.
- Application: Industrial abrasive, white sand for molds.
40-45 AFS
- Typical Use: Slightly finer than 30-35 AFS, used for finer casting details, core making.
- Grain Size Range: 390-330 µm for main fraction; low clay content (0.14-0.24%).
- Chemical Composition: Silica content near 100%, white to off-white sand.
- Application: Industrial abrasive, more intricate mold surfaces.
50-55 AFS
- Typical Use: Used where finer surface finish is needed in casting and molding.
- Grain Size Range: 270-240 µm for main fraction; clay content 0.2-0.3%.
- Chemical Composition: Silica content 99% or higher, <0.01% clay, high purity.
- Application: Industrial abrasive, core and mold making requiring smoother surfaces.
55-60 AFS
- Typical Use: Fine grain for high-detail casting, especially in ferrous and non-ferrous metal foundries.
- Grain Size Range: 240-210 µm main fraction, clay 0.2-0.3%.
- Chemical Composition: White silica sand, high silica content.
- Application: Used in industrial molds with highest detail requirements.
60-70 AFS
- Typical Use: Very fine sand, used in heavy-duty, precision casting or special industrial applications.
- Grain Size Range: 210–180 µm and lower, with possible secondary fractions around 150 µm or less.
- Chemical Composition: Silica content remains high, 0.3–0.5% clay for higher AFS numbers.
- Application: Molding sand for intricate parts, filtration, advanced foundry processes.
70-75 AFS
- Typical Use: One of the finest standard sand grades for foundries focusing on critical/high-precision castings.
- Grain Size Range: 180-170 µm, clay 0.4-0.6%.
- Chemical Composition: Silica content high, with increased uniformity as AFS increases.
- Application: Ultra-fine molds, cores, and specialty sand-casting where highest mold definition is required.
General Properties Across All AFS Bands Listed
- Uniformity: Higher AFS = finer and more uniform grains.
- Silica Content: Typically 98-100% SiO2; lower impurity levels for higher quality.
- Clay/Silt: Clay and silt content is kept very low (0.1–0.6%), as required for foundry standards.
- Density: Approx. 2,640 kg/m³.
- Color: Generally white to light grey.
- Packaging Methods: Bulk, bagged (HDPE/50 kg/1 MT), dust, or granule form depending on end-use.
Parameters for Main AFS Grades
|
AFS No.
|
Main Grain Fraction (µm)
|
Clay (%)
|
Typical Usage
|
|---|---|---|---|
|
30–35
|
450–600
|
0.1–0.2
|
General molding & abrasive
|
|
40–45
|
390–330
|
0.14–0.24
|
Finer cores, more detailed molds
|
|
50–55
|
270–240
|
0.2–0.3
|
Smooth casting surfaces
|
|
55–60
|
240–210
|
0.2–0.3
|
High-detail castings and core molds
|
|
60–70
|
210–180
|
0.3–0.5
|
Precision and intricate mold work
|
|
70–75
|
180–170
|
0.4–0.6
|
Ultra-high precision, fine core work
|
Important Notes and Caveats
- Actual values for sand distribution and chemical composition vary slightly by supplier and region.
- Some properties such as permeability, refractoriness, and strength are not specified here but are typically tested according to end-use and industry standards.
- AFS numbers are determined by standardized sieve analysis, evaluating grain size and uniformity.
For supplier-specific properties, check datasheets or product websites, as each may offer slight variations in specifications.